2 /* pngrtran.c - transforms the data in a row for PNG readers
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4 * Last changed in libpng 1.5.7 [December 15, 2011]
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5 * Copyright (c) 1998-2011 Glenn Randers-Pehrson
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6 * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
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7 * (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)
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9 * This code is released under the libpng license.
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10 * For conditions of distribution and use, see the disclaimer
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11 * and license in png.h
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13 * This file contains functions optionally called by an application
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14 * in order to tell libpng how to handle data when reading a PNG.
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15 * Transformations that are used in both reading and writing are
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19 #include "pngpriv.h"
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21 #ifdef PNG_READ_SUPPORTED
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23 /* Set the action on getting a CRC error for an ancillary or critical chunk. */
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25 png_set_crc_action(png_structp png_ptr, int crit_action, int ancil_action)
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27 png_debug(1, "in png_set_crc_action");
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29 if (png_ptr == NULL)
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32 /* Tell libpng how we react to CRC errors in critical chunks */
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33 switch (crit_action)
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35 case PNG_CRC_NO_CHANGE: /* Leave setting as is */
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38 case PNG_CRC_WARN_USE: /* Warn/use data */
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39 png_ptr->flags &= ~PNG_FLAG_CRC_CRITICAL_MASK;
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40 png_ptr->flags |= PNG_FLAG_CRC_CRITICAL_USE;
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43 case PNG_CRC_QUIET_USE: /* Quiet/use data */
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44 png_ptr->flags &= ~PNG_FLAG_CRC_CRITICAL_MASK;
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45 png_ptr->flags |= PNG_FLAG_CRC_CRITICAL_USE |
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46 PNG_FLAG_CRC_CRITICAL_IGNORE;
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49 case PNG_CRC_WARN_DISCARD: /* Not a valid action for critical data */
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50 png_warning(png_ptr,
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51 "Can't discard critical data on CRC error");
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52 case PNG_CRC_ERROR_QUIT: /* Error/quit */
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54 case PNG_CRC_DEFAULT:
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56 png_ptr->flags &= ~PNG_FLAG_CRC_CRITICAL_MASK;
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60 /* Tell libpng how we react to CRC errors in ancillary chunks */
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61 switch (ancil_action)
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63 case PNG_CRC_NO_CHANGE: /* Leave setting as is */
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66 case PNG_CRC_WARN_USE: /* Warn/use data */
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67 png_ptr->flags &= ~PNG_FLAG_CRC_ANCILLARY_MASK;
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68 png_ptr->flags |= PNG_FLAG_CRC_ANCILLARY_USE;
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71 case PNG_CRC_QUIET_USE: /* Quiet/use data */
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72 png_ptr->flags &= ~PNG_FLAG_CRC_ANCILLARY_MASK;
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73 png_ptr->flags |= PNG_FLAG_CRC_ANCILLARY_USE |
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74 PNG_FLAG_CRC_ANCILLARY_NOWARN;
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77 case PNG_CRC_ERROR_QUIT: /* Error/quit */
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78 png_ptr->flags &= ~PNG_FLAG_CRC_ANCILLARY_MASK;
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79 png_ptr->flags |= PNG_FLAG_CRC_ANCILLARY_NOWARN;
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82 case PNG_CRC_WARN_DISCARD: /* Warn/discard data */
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84 case PNG_CRC_DEFAULT:
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86 png_ptr->flags &= ~PNG_FLAG_CRC_ANCILLARY_MASK;
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91 #ifdef PNG_READ_BACKGROUND_SUPPORTED
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92 /* Handle alpha and tRNS via a background color */
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94 png_set_background_fixed(png_structp png_ptr,
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95 png_const_color_16p background_color, int background_gamma_code,
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96 int need_expand, png_fixed_point background_gamma)
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98 png_debug(1, "in png_set_background_fixed");
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100 if (png_ptr == NULL)
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103 if (background_gamma_code == PNG_BACKGROUND_GAMMA_UNKNOWN)
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105 png_warning(png_ptr, "Application must supply a known background gamma");
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109 png_ptr->transformations |= PNG_COMPOSE | PNG_STRIP_ALPHA;
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110 png_ptr->transformations &= ~PNG_ENCODE_ALPHA;
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111 png_ptr->flags &= ~PNG_FLAG_OPTIMIZE_ALPHA;
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113 png_memcpy(&(png_ptr->background), background_color,
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114 png_sizeof(png_color_16));
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115 png_ptr->background_gamma = background_gamma;
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116 png_ptr->background_gamma_type = (png_byte)(background_gamma_code);
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118 png_ptr->transformations |= PNG_BACKGROUND_EXPAND;
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120 png_ptr->transformations &= ~PNG_BACKGROUND_EXPAND;
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123 # ifdef PNG_FLOATING_POINT_SUPPORTED
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125 png_set_background(png_structp png_ptr,
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126 png_const_color_16p background_color, int background_gamma_code,
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127 int need_expand, double background_gamma)
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129 png_set_background_fixed(png_ptr, background_color, background_gamma_code,
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130 need_expand, png_fixed(png_ptr, background_gamma, "png_set_background"));
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132 # endif /* FLOATING_POINT */
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133 #endif /* READ_BACKGROUND */
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135 /* Scale 16-bit depth files to 8-bit depth. If both of these are set then the
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136 * one that pngrtran does first (scale) happens. This is necessary to allow the
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137 * TRANSFORM and API behavior to be somewhat consistent, and it's simpler.
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139 #ifdef PNG_READ_SCALE_16_TO_8_SUPPORTED
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141 png_set_scale_16(png_structp png_ptr)
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143 png_debug(1, "in png_set_scale_16");
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145 if (png_ptr == NULL)
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148 png_ptr->transformations |= PNG_SCALE_16_TO_8;
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152 #ifdef PNG_READ_STRIP_16_TO_8_SUPPORTED
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153 /* Chop 16-bit depth files to 8-bit depth */
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155 png_set_strip_16(png_structp png_ptr)
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157 png_debug(1, "in png_set_strip_16");
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159 if (png_ptr == NULL)
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162 png_ptr->transformations |= PNG_16_TO_8;
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166 #ifdef PNG_READ_STRIP_ALPHA_SUPPORTED
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168 png_set_strip_alpha(png_structp png_ptr)
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170 png_debug(1, "in png_set_strip_alpha");
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172 if (png_ptr == NULL)
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175 png_ptr->transformations |= PNG_STRIP_ALPHA;
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179 #if defined(PNG_READ_ALPHA_MODE_SUPPORTED) || defined(PNG_READ_GAMMA_SUPPORTED)
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180 static png_fixed_point
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181 translate_gamma_flags(png_structp png_ptr, png_fixed_point output_gamma,
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184 /* Check for flag values. The main reason for having the old Mac value as a
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185 * flag is that it is pretty near impossible to work out what the correct
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186 * value is from Apple documentation - a working Mac system is needed to
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187 * discover the value!
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189 if (output_gamma == PNG_DEFAULT_sRGB ||
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190 output_gamma == PNG_FP_1 / PNG_DEFAULT_sRGB)
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192 /* If there is no sRGB support this just sets the gamma to the standard
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193 * sRGB value. (This is a side effect of using this function!)
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195 # ifdef PNG_READ_sRGB_SUPPORTED
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196 png_ptr->flags |= PNG_FLAG_ASSUME_sRGB;
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199 output_gamma = PNG_GAMMA_sRGB;
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201 output_gamma = PNG_GAMMA_sRGB_INVERSE;
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204 else if (output_gamma == PNG_GAMMA_MAC_18 ||
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205 output_gamma == PNG_FP_1 / PNG_GAMMA_MAC_18)
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208 output_gamma = PNG_GAMMA_MAC_OLD;
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210 output_gamma = PNG_GAMMA_MAC_INVERSE;
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213 return output_gamma;
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216 # ifdef PNG_FLOATING_POINT_SUPPORTED
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217 static png_fixed_point
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218 convert_gamma_value(png_structp png_ptr, double output_gamma)
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220 /* The following silently ignores cases where fixed point (times 100,000)
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221 * gamma values are passed to the floating point API. This is safe and it
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222 * means the fixed point constants work just fine with the floating point
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223 * API. The alternative would just lead to undetected errors and spurious
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224 * bug reports. Negative values fail inside the _fixed API unless they
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225 * correspond to the flag values.
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227 if (output_gamma > 0 && output_gamma < 128)
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228 output_gamma *= PNG_FP_1;
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230 /* This preserves -1 and -2 exactly: */
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231 output_gamma = floor(output_gamma + .5);
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233 if (output_gamma > PNG_FP_MAX || output_gamma < PNG_FP_MIN)
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234 png_fixed_error(png_ptr, "gamma value");
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236 return (png_fixed_point)output_gamma;
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239 #endif /* READ_ALPHA_MODE || READ_GAMMA */
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241 #ifdef PNG_READ_ALPHA_MODE_SUPPORTED
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243 png_set_alpha_mode_fixed(png_structp png_ptr, int mode,
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244 png_fixed_point output_gamma)
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247 png_fixed_point file_gamma;
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249 png_debug(1, "in png_set_alpha_mode");
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251 if (png_ptr == NULL)
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254 output_gamma = translate_gamma_flags(png_ptr, output_gamma, 1/*screen*/);
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256 /* Validate the value to ensure it is in a reasonable range. The value
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257 * is expected to be 1 or greater, but this range test allows for some
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258 * viewing correction values. The intent is to weed out users of this API
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259 * who use the inverse of the gamma value accidentally! Since some of these
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260 * values are reasonable this may have to be changed.
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262 if (output_gamma < 70000 || output_gamma > 300000)
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263 png_error(png_ptr, "output gamma out of expected range");
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265 /* The default file gamma is the inverse of the output gamma; the output
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266 * gamma may be changed below so get the file value first:
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268 file_gamma = png_reciprocal(output_gamma);
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270 /* There are really 8 possibilities here, composed of any combination
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273 * premultiply the color channels
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274 * do not encode non-opaque pixels
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275 * encode the alpha as well as the color channels
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277 * The differences disappear if the input/output ('screen') gamma is 1.0,
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278 * because then the encoding is a no-op and there is only the choice of
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279 * premultiplying the color channels or not.
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281 * png_set_alpha_mode and png_set_background interact because both use
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282 * png_compose to do the work. Calling both is only useful when
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283 * png_set_alpha_mode is used to set the default mode - PNG_ALPHA_PNG - along
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284 * with a default gamma value. Otherwise PNG_COMPOSE must not be set.
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288 case PNG_ALPHA_PNG: /* default: png standard */
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289 /* No compose, but it may be set by png_set_background! */
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290 png_ptr->transformations &= ~PNG_ENCODE_ALPHA;
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291 png_ptr->flags &= ~PNG_FLAG_OPTIMIZE_ALPHA;
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294 case PNG_ALPHA_ASSOCIATED: /* color channels premultiplied */
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296 png_ptr->transformations &= ~PNG_ENCODE_ALPHA;
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297 png_ptr->flags &= ~PNG_FLAG_OPTIMIZE_ALPHA;
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298 /* The output is linear: */
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299 output_gamma = PNG_FP_1;
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302 case PNG_ALPHA_OPTIMIZED: /* associated, non-opaque pixels linear */
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304 png_ptr->transformations &= ~PNG_ENCODE_ALPHA;
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305 png_ptr->flags |= PNG_FLAG_OPTIMIZE_ALPHA;
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306 /* output_gamma records the encoding of opaque pixels! */
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309 case PNG_ALPHA_BROKEN: /* associated, non-linear, alpha encoded */
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311 png_ptr->transformations |= PNG_ENCODE_ALPHA;
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312 png_ptr->flags &= ~PNG_FLAG_OPTIMIZE_ALPHA;
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316 png_error(png_ptr, "invalid alpha mode");
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319 /* Only set the default gamma if the file gamma has not been set (this has
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320 * the side effect that the gamma in a second call to png_set_alpha_mode will
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323 if (png_ptr->gamma == 0)
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324 png_ptr->gamma = file_gamma;
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326 /* But always set the output gamma: */
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327 png_ptr->screen_gamma = output_gamma;
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329 /* Finally, if pre-multiplying, set the background fields to achieve the
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334 /* And obtain alpha pre-multiplication by composing on black: */
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335 png_memset(&png_ptr->background, 0, sizeof png_ptr->background);
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336 png_ptr->background_gamma = png_ptr->gamma; /* just in case */
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337 png_ptr->background_gamma_type = PNG_BACKGROUND_GAMMA_FILE;
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338 png_ptr->transformations &= ~PNG_BACKGROUND_EXPAND;
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340 if (png_ptr->transformations & PNG_COMPOSE)
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342 "conflicting calls to set alpha mode and background");
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344 png_ptr->transformations |= PNG_COMPOSE;
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347 /* New API, make sure apps call the correct initializers: */
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348 png_ptr->flags |= PNG_FLAG_DETECT_UNINITIALIZED;
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351 # ifdef PNG_FLOATING_POINT_SUPPORTED
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353 png_set_alpha_mode(png_structp png_ptr, int mode, double output_gamma)
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355 png_set_alpha_mode_fixed(png_ptr, mode, convert_gamma_value(png_ptr,
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361 #ifdef PNG_READ_QUANTIZE_SUPPORTED
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362 /* Dither file to 8-bit. Supply a palette, the current number
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363 * of elements in the palette, the maximum number of elements
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364 * allowed, and a histogram if possible. If the current number
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365 * of colors is greater then the maximum number, the palette will be
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366 * modified to fit in the maximum number. "full_quantize" indicates
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367 * whether we need a quantizing cube set up for RGB images, or if we
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368 * simply are reducing the number of colors in a paletted image.
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371 typedef struct png_dsort_struct
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373 struct png_dsort_struct FAR * next;
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377 typedef png_dsort FAR * png_dsortp;
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378 typedef png_dsort FAR * FAR * png_dsortpp;
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381 png_set_quantize(png_structp png_ptr, png_colorp palette,
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382 int num_palette, int maximum_colors, png_const_uint_16p histogram,
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385 png_debug(1, "in png_set_quantize");
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387 if (png_ptr == NULL)
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390 png_ptr->transformations |= PNG_QUANTIZE;
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392 if (!full_quantize)
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396 png_ptr->quantize_index = (png_bytep)png_malloc(png_ptr,
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397 (png_uint_32)(num_palette * png_sizeof(png_byte)));
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398 for (i = 0; i < num_palette; i++)
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399 png_ptr->quantize_index[i] = (png_byte)i;
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402 if (num_palette > maximum_colors)
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404 if (histogram != NULL)
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406 /* This is easy enough, just throw out the least used colors.
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407 * Perhaps not the best solution, but good enough.
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412 /* Initialize an array to sort colors */
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413 png_ptr->quantize_sort = (png_bytep)png_malloc(png_ptr,
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414 (png_uint_32)(num_palette * png_sizeof(png_byte)));
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416 /* Initialize the quantize_sort array */
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417 for (i = 0; i < num_palette; i++)
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418 png_ptr->quantize_sort[i] = (png_byte)i;
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420 /* Find the least used palette entries by starting a
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421 * bubble sort, and running it until we have sorted
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422 * out enough colors. Note that we don't care about
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423 * sorting all the colors, just finding which are
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427 for (i = num_palette - 1; i >= maximum_colors; i--)
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429 int done; /* To stop early if the list is pre-sorted */
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433 for (j = 0; j < i; j++)
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435 if (histogram[png_ptr->quantize_sort[j]]
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436 < histogram[png_ptr->quantize_sort[j + 1]])
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440 t = png_ptr->quantize_sort[j];
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441 png_ptr->quantize_sort[j] = png_ptr->quantize_sort[j + 1];
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442 png_ptr->quantize_sort[j + 1] = t;
\r
451 /* Swap the palette around, and set up a table, if necessary */
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454 int j = num_palette;
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456 /* Put all the useful colors within the max, but don't
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459 for (i = 0; i < maximum_colors; i++)
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461 if ((int)png_ptr->quantize_sort[i] >= maximum_colors)
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465 while ((int)png_ptr->quantize_sort[j] >= maximum_colors);
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467 palette[i] = palette[j];
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473 int j = num_palette;
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475 /* Move all the used colors inside the max limit, and
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476 * develop a translation table.
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478 for (i = 0; i < maximum_colors; i++)
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480 /* Only move the colors we need to */
\r
481 if ((int)png_ptr->quantize_sort[i] >= maximum_colors)
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483 png_color tmp_color;
\r
487 while ((int)png_ptr->quantize_sort[j] >= maximum_colors);
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489 tmp_color = palette[j];
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490 palette[j] = palette[i];
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491 palette[i] = tmp_color;
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492 /* Indicate where the color went */
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493 png_ptr->quantize_index[j] = (png_byte)i;
\r
494 png_ptr->quantize_index[i] = (png_byte)j;
\r
498 /* Find closest color for those colors we are not using */
\r
499 for (i = 0; i < num_palette; i++)
\r
501 if ((int)png_ptr->quantize_index[i] >= maximum_colors)
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503 int min_d, k, min_k, d_index;
\r
505 /* Find the closest color to one we threw out */
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506 d_index = png_ptr->quantize_index[i];
\r
507 min_d = PNG_COLOR_DIST(palette[d_index], palette[0]);
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508 for (k = 1, min_k = 0; k < maximum_colors; k++)
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512 d = PNG_COLOR_DIST(palette[d_index], palette[k]);
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520 /* Point to closest color */
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521 png_ptr->quantize_index[i] = (png_byte)min_k;
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525 png_free(png_ptr, png_ptr->quantize_sort);
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526 png_ptr->quantize_sort = NULL;
\r
530 /* This is much harder to do simply (and quickly). Perhaps
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531 * we need to go through a median cut routine, but those
\r
532 * don't always behave themselves with only a few colors
\r
533 * as input. So we will just find the closest two colors,
\r
534 * and throw out one of them (chosen somewhat randomly).
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535 * [We don't understand this at all, so if someone wants to
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536 * work on improving it, be our guest - AED, GRP]
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540 int num_new_palette;
\r
546 /* Initialize palette index arrays */
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547 png_ptr->index_to_palette = (png_bytep)png_malloc(png_ptr,
\r
548 (png_uint_32)(num_palette * png_sizeof(png_byte)));
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549 png_ptr->palette_to_index = (png_bytep)png_malloc(png_ptr,
\r
550 (png_uint_32)(num_palette * png_sizeof(png_byte)));
\r
552 /* Initialize the sort array */
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553 for (i = 0; i < num_palette; i++)
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555 png_ptr->index_to_palette[i] = (png_byte)i;
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556 png_ptr->palette_to_index[i] = (png_byte)i;
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559 hash = (png_dsortpp)png_calloc(png_ptr, (png_uint_32)(769 *
\r
560 png_sizeof(png_dsortp)));
\r
562 num_new_palette = num_palette;
\r
564 /* Initial wild guess at how far apart the farthest pixel
\r
565 * pair we will be eliminating will be. Larger
\r
566 * numbers mean more areas will be allocated, Smaller
\r
567 * numbers run the risk of not saving enough data, and
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568 * having to do this all over again.
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570 * I have not done extensive checking on this number.
\r
574 while (num_new_palette > maximum_colors)
\r
576 for (i = 0; i < num_new_palette - 1; i++)
\r
580 for (j = i + 1; j < num_new_palette; j++)
\r
584 d = PNG_COLOR_DIST(palette[i], palette[j]);
\r
589 t = (png_dsortp)png_malloc_warn(png_ptr,
\r
590 (png_uint_32)(png_sizeof(png_dsort)));
\r
596 t->left = (png_byte)i;
\r
597 t->right = (png_byte)j;
\r
606 for (i = 0; i <= max_d; i++)
\r
608 if (hash[i] != NULL)
\r
612 for (p = hash[i]; p; p = p->next)
\r
614 if ((int)png_ptr->index_to_palette[p->left]
\r
615 < num_new_palette &&
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616 (int)png_ptr->index_to_palette[p->right]
\r
621 if (num_new_palette & 0x01)
\r
633 palette[png_ptr->index_to_palette[j]]
\r
634 = palette[num_new_palette];
\r
635 if (!full_quantize)
\r
639 for (k = 0; k < num_palette; k++)
\r
641 if (png_ptr->quantize_index[k] ==
\r
642 png_ptr->index_to_palette[j])
\r
643 png_ptr->quantize_index[k] =
\r
644 png_ptr->index_to_palette[next_j];
\r
646 if ((int)png_ptr->quantize_index[k] ==
\r
648 png_ptr->quantize_index[k] =
\r
649 png_ptr->index_to_palette[j];
\r
653 png_ptr->index_to_palette[png_ptr->palette_to_index
\r
654 [num_new_palette]] = png_ptr->index_to_palette[j];
\r
656 png_ptr->palette_to_index[png_ptr->index_to_palette[j]]
\r
657 = png_ptr->palette_to_index[num_new_palette];
\r
659 png_ptr->index_to_palette[j] =
\r
660 (png_byte)num_new_palette;
\r
662 png_ptr->palette_to_index[num_new_palette] =
\r
665 if (num_new_palette <= maximum_colors)
\r
668 if (num_new_palette <= maximum_colors)
\r
673 for (i = 0; i < 769; i++)
\r
675 if (hash[i] != NULL)
\r
677 png_dsortp p = hash[i];
\r
681 png_free(png_ptr, p);
\r
689 png_free(png_ptr, hash);
\r
690 png_free(png_ptr, png_ptr->palette_to_index);
\r
691 png_free(png_ptr, png_ptr->index_to_palette);
\r
692 png_ptr->palette_to_index = NULL;
\r
693 png_ptr->index_to_palette = NULL;
\r
695 num_palette = maximum_colors;
\r
697 if (png_ptr->palette == NULL)
\r
699 png_ptr->palette = palette;
\r
701 png_ptr->num_palette = (png_uint_16)num_palette;
\r
706 png_bytep distance;
\r
707 int total_bits = PNG_QUANTIZE_RED_BITS + PNG_QUANTIZE_GREEN_BITS +
\r
708 PNG_QUANTIZE_BLUE_BITS;
\r
709 int num_red = (1 << PNG_QUANTIZE_RED_BITS);
\r
710 int num_green = (1 << PNG_QUANTIZE_GREEN_BITS);
\r
711 int num_blue = (1 << PNG_QUANTIZE_BLUE_BITS);
\r
712 png_size_t num_entries = ((png_size_t)1 << total_bits);
\r
714 png_ptr->palette_lookup = (png_bytep)png_calloc(png_ptr,
\r
715 (png_uint_32)(num_entries * png_sizeof(png_byte)));
\r
717 distance = (png_bytep)png_malloc(png_ptr, (png_uint_32)(num_entries *
\r
718 png_sizeof(png_byte)));
\r
720 png_memset(distance, 0xff, num_entries * png_sizeof(png_byte));
\r
722 for (i = 0; i < num_palette; i++)
\r
725 int r = (palette[i].red >> (8 - PNG_QUANTIZE_RED_BITS));
\r
726 int g = (palette[i].green >> (8 - PNG_QUANTIZE_GREEN_BITS));
\r
727 int b = (palette[i].blue >> (8 - PNG_QUANTIZE_BLUE_BITS));
\r
729 for (ir = 0; ir < num_red; ir++)
\r
731 /* int dr = abs(ir - r); */
\r
732 int dr = ((ir > r) ? ir - r : r - ir);
\r
733 int index_r = (ir << (PNG_QUANTIZE_BLUE_BITS +
\r
734 PNG_QUANTIZE_GREEN_BITS));
\r
736 for (ig = 0; ig < num_green; ig++)
\r
738 /* int dg = abs(ig - g); */
\r
739 int dg = ((ig > g) ? ig - g : g - ig);
\r
741 int dm = ((dr > dg) ? dr : dg);
\r
742 int index_g = index_r | (ig << PNG_QUANTIZE_BLUE_BITS);
\r
744 for (ib = 0; ib < num_blue; ib++)
\r
746 int d_index = index_g | ib;
\r
747 /* int db = abs(ib - b); */
\r
748 int db = ((ib > b) ? ib - b : b - ib);
\r
749 int dmax = ((dm > db) ? dm : db);
\r
750 int d = dmax + dt + db;
\r
752 if (d < (int)distance[d_index])
\r
754 distance[d_index] = (png_byte)d;
\r
755 png_ptr->palette_lookup[d_index] = (png_byte)i;
\r
762 png_free(png_ptr, distance);
\r
765 #endif /* PNG_READ_QUANTIZE_SUPPORTED */
\r
767 #ifdef PNG_READ_GAMMA_SUPPORTED
\r
769 png_set_gamma_fixed(png_structp png_ptr, png_fixed_point scrn_gamma,
\r
770 png_fixed_point file_gamma)
\r
772 png_debug(1, "in png_set_gamma_fixed");
\r
774 if (png_ptr == NULL)
\r
777 /* New in libpng-1.5.4 - reserve particular negative values as flags. */
\r
778 scrn_gamma = translate_gamma_flags(png_ptr, scrn_gamma, 1/*screen*/);
\r
779 file_gamma = translate_gamma_flags(png_ptr, file_gamma, 0/*file*/);
\r
781 #if PNG_LIBPNG_VER >= 10600
\r
782 /* Checking the gamma values for being >0 was added in 1.5.4 along with the
\r
783 * premultiplied alpha support; this actually hides an undocumented feature
\r
784 * of the previous implementation which allowed gamma processing to be
\r
785 * disabled in background handling. There is no evidence (so far) that this
\r
786 * was being used; however, png_set_background itself accepted and must still
\r
787 * accept '0' for the gamma value it takes, because it isn't always used.
\r
789 * Since this is an API change (albeit a very minor one that removes an
\r
790 * undocumented API feature) it will not be made until libpng-1.6.0.
\r
792 if (file_gamma <= 0)
\r
793 png_error(png_ptr, "invalid file gamma in png_set_gamma");
\r
795 if (scrn_gamma <= 0)
\r
796 png_error(png_ptr, "invalid screen gamma in png_set_gamma");
\r
799 /* Set the gamma values unconditionally - this overrides the value in the PNG
\r
800 * file if a gAMA chunk was present. png_set_alpha_mode provides a
\r
801 * different, easier, way to default the file gamma.
\r
803 png_ptr->gamma = file_gamma;
\r
804 png_ptr->screen_gamma = scrn_gamma;
\r
807 # ifdef PNG_FLOATING_POINT_SUPPORTED
\r
809 png_set_gamma(png_structp png_ptr, double scrn_gamma, double file_gamma)
\r
811 png_set_gamma_fixed(png_ptr, convert_gamma_value(png_ptr, scrn_gamma),
\r
812 convert_gamma_value(png_ptr, file_gamma));
\r
814 # endif /* FLOATING_POINT_SUPPORTED */
\r
815 #endif /* READ_GAMMA */
\r
817 #ifdef PNG_READ_EXPAND_SUPPORTED
\r
818 /* Expand paletted images to RGB, expand grayscale images of
\r
819 * less than 8-bit depth to 8-bit depth, and expand tRNS chunks
\r
820 * to alpha channels.
\r
823 png_set_expand(png_structp png_ptr)
\r
825 png_debug(1, "in png_set_expand");
\r
827 if (png_ptr == NULL)
\r
830 png_ptr->transformations |= (PNG_EXPAND | PNG_EXPAND_tRNS);
\r
831 png_ptr->flags &= ~PNG_FLAG_ROW_INIT;
\r
834 /* GRR 19990627: the following three functions currently are identical
\r
835 * to png_set_expand(). However, it is entirely reasonable that someone
\r
836 * might wish to expand an indexed image to RGB but *not* expand a single,
\r
837 * fully transparent palette entry to a full alpha channel--perhaps instead
\r
838 * convert tRNS to the grayscale/RGB format (16-bit RGB value), or replace
\r
839 * the transparent color with a particular RGB value, or drop tRNS entirely.
\r
840 * IOW, a future version of the library may make the transformations flag
\r
841 * a bit more fine-grained, with separate bits for each of these three
\r
844 * More to the point, these functions make it obvious what libpng will be
\r
845 * doing, whereas "expand" can (and does) mean any number of things.
\r
847 * GRP 20060307: In libpng-1.2.9, png_set_gray_1_2_4_to_8() was modified
\r
848 * to expand only the sample depth but not to expand the tRNS to alpha
\r
849 * and its name was changed to png_set_expand_gray_1_2_4_to_8().
\r
852 /* Expand paletted images to RGB. */
\r
854 png_set_palette_to_rgb(png_structp png_ptr)
\r
856 png_debug(1, "in png_set_palette_to_rgb");
\r
858 if (png_ptr == NULL)
\r
861 png_ptr->transformations |= (PNG_EXPAND | PNG_EXPAND_tRNS);
\r
862 png_ptr->flags &= ~PNG_FLAG_ROW_INIT;
\r
865 /* Expand grayscale images of less than 8-bit depth to 8 bits. */
\r
867 png_set_expand_gray_1_2_4_to_8(png_structp png_ptr)
\r
869 png_debug(1, "in png_set_expand_gray_1_2_4_to_8");
\r
871 if (png_ptr == NULL)
\r
874 png_ptr->transformations |= PNG_EXPAND;
\r
875 png_ptr->flags &= ~PNG_FLAG_ROW_INIT;
\r
880 /* Expand tRNS chunks to alpha channels. */
\r
882 png_set_tRNS_to_alpha(png_structp png_ptr)
\r
884 png_debug(1, "in png_set_tRNS_to_alpha");
\r
886 png_ptr->transformations |= (PNG_EXPAND | PNG_EXPAND_tRNS);
\r
887 png_ptr->flags &= ~PNG_FLAG_ROW_INIT;
\r
889 #endif /* defined(PNG_READ_EXPAND_SUPPORTED) */
\r
891 #ifdef PNG_READ_EXPAND_16_SUPPORTED
\r
892 /* Expand to 16-bit channels, expand the tRNS chunk too (because otherwise
\r
893 * it may not work correctly.)
\r
896 png_set_expand_16(png_structp png_ptr)
\r
898 png_debug(1, "in png_set_expand_16");
\r
900 if (png_ptr == NULL)
\r
903 png_ptr->transformations |= (PNG_EXPAND_16 | PNG_EXPAND | PNG_EXPAND_tRNS);
\r
904 png_ptr->flags &= ~PNG_FLAG_ROW_INIT;
\r
906 /* New API, make sure apps call the correct initializers: */
\r
907 png_ptr->flags |= PNG_FLAG_DETECT_UNINITIALIZED;
\r
911 #ifdef PNG_READ_GRAY_TO_RGB_SUPPORTED
\r
913 png_set_gray_to_rgb(png_structp png_ptr)
\r
915 png_debug(1, "in png_set_gray_to_rgb");
\r
917 if (png_ptr != NULL)
\r
919 /* Because rgb must be 8 bits or more: */
\r
920 png_set_expand_gray_1_2_4_to_8(png_ptr);
\r
921 png_ptr->transformations |= PNG_GRAY_TO_RGB;
\r
922 png_ptr->flags &= ~PNG_FLAG_ROW_INIT;
\r
927 #ifdef PNG_READ_RGB_TO_GRAY_SUPPORTED
\r
929 png_set_rgb_to_gray_fixed(png_structp png_ptr, int error_action,
\r
930 png_fixed_point red, png_fixed_point green)
\r
932 png_debug(1, "in png_set_rgb_to_gray");
\r
934 if (png_ptr == NULL)
\r
937 switch(error_action)
\r
939 case PNG_ERROR_ACTION_NONE:
\r
940 png_ptr->transformations |= PNG_RGB_TO_GRAY;
\r
943 case PNG_ERROR_ACTION_WARN:
\r
944 png_ptr->transformations |= PNG_RGB_TO_GRAY_WARN;
\r
947 case PNG_ERROR_ACTION_ERROR:
\r
948 png_ptr->transformations |= PNG_RGB_TO_GRAY_ERR;
\r
952 png_error(png_ptr, "invalid error action to rgb_to_gray");
\r
955 if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE)
\r
956 #ifdef PNG_READ_EXPAND_SUPPORTED
\r
957 png_ptr->transformations |= PNG_EXPAND;
\r
960 png_warning(png_ptr,
\r
961 "Cannot do RGB_TO_GRAY without EXPAND_SUPPORTED");
\r
963 png_ptr->transformations &= ~PNG_RGB_TO_GRAY;
\r
967 if (red >= 0 && green >= 0 && red + green <= PNG_FP_1)
\r
969 png_uint_16 red_int, green_int;
\r
971 /* NOTE: this calculation does not round, but this behavior is retained
\r
972 * for consistency, the inaccuracy is very small. The code here always
\r
973 * overwrites the coefficients, regardless of whether they have been
\r
974 * defaulted or set already.
\r
976 red_int = (png_uint_16)(((png_uint_32)red*32768)/100000);
\r
977 green_int = (png_uint_16)(((png_uint_32)green*32768)/100000);
\r
979 png_ptr->rgb_to_gray_red_coeff = red_int;
\r
980 png_ptr->rgb_to_gray_green_coeff = green_int;
\r
981 png_ptr->rgb_to_gray_coefficients_set = 1;
\r
986 if (red >= 0 && green >= 0)
\r
987 png_warning(png_ptr,
\r
988 "ignoring out of range rgb_to_gray coefficients");
\r
990 /* Use the defaults, from the cHRM chunk if set, else the historical
\r
991 * values which are close to the sRGB/HDTV/ITU-Rec 709 values. See
\r
992 * png_do_rgb_to_gray for more discussion of the values. In this case
\r
993 * the coefficients are not marked as 'set' and are not overwritten if
\r
994 * something has already provided a default.
\r
996 if (png_ptr->rgb_to_gray_red_coeff == 0 &&
\r
997 png_ptr->rgb_to_gray_green_coeff == 0)
\r
999 png_ptr->rgb_to_gray_red_coeff = 6968;
\r
1000 png_ptr->rgb_to_gray_green_coeff = 23434;
\r
1001 /* png_ptr->rgb_to_gray_blue_coeff = 2366; */
\r
1007 #ifdef PNG_FLOATING_POINT_SUPPORTED
\r
1008 /* Convert a RGB image to a grayscale of the same width. This allows us,
\r
1009 * for example, to convert a 24 bpp RGB image into an 8 bpp grayscale image.
\r
1013 png_set_rgb_to_gray(png_structp png_ptr, int error_action, double red,
\r
1016 if (png_ptr == NULL)
\r
1019 png_set_rgb_to_gray_fixed(png_ptr, error_action,
\r
1020 png_fixed(png_ptr, red, "rgb to gray red coefficient"),
\r
1021 png_fixed(png_ptr, green, "rgb to gray green coefficient"));
\r
1023 #endif /* FLOATING POINT */
\r
1027 #if defined(PNG_READ_USER_TRANSFORM_SUPPORTED) || \
\r
1028 defined(PNG_WRITE_USER_TRANSFORM_SUPPORTED)
\r
1030 png_set_read_user_transform_fn(png_structp png_ptr, png_user_transform_ptr
\r
1031 read_user_transform_fn)
\r
1033 png_debug(1, "in png_set_read_user_transform_fn");
\r
1035 if (png_ptr == NULL)
\r
1038 #ifdef PNG_READ_USER_TRANSFORM_SUPPORTED
\r
1039 png_ptr->transformations |= PNG_USER_TRANSFORM;
\r
1040 png_ptr->read_user_transform_fn = read_user_transform_fn;
\r
1045 #ifdef PNG_READ_TRANSFORMS_SUPPORTED
\r
1046 #ifdef PNG_READ_GAMMA_SUPPORTED
\r
1047 /* In the case of gamma transformations only do transformations on images where
\r
1048 * the [file] gamma and screen_gamma are not close reciprocals, otherwise it
\r
1049 * slows things down slightly, and also needlessly introduces small errors.
\r
1051 static int /* PRIVATE */
\r
1052 png_gamma_threshold(png_fixed_point screen_gamma, png_fixed_point file_gamma)
\r
1054 /* PNG_GAMMA_THRESHOLD is the threshold for performing gamma
\r
1055 * correction as a difference of the overall transform from 1.0
\r
1057 * We want to compare the threshold with s*f - 1, if we get
\r
1058 * overflow here it is because of wacky gamma values so we
\r
1059 * turn on processing anyway.
\r
1061 png_fixed_point gtest;
\r
1062 return !png_muldiv(>est, screen_gamma, file_gamma, PNG_FP_1) ||
\r
1063 png_gamma_significant(gtest);
\r
1067 /* Initialize everything needed for the read. This includes modifying
\r
1071 /*For the moment 'png_init_palette_transformations' and
\r
1072 * 'png_init_rgb_transformations' only do some flag canceling optimizations.
\r
1073 * The intent is that these two routines should have palette or rgb operations
\r
1074 * extracted from 'png_init_read_transformations'.
\r
1076 static void /* PRIVATE */
\r
1077 png_init_palette_transformations(png_structp png_ptr)
\r
1079 /* Called to handle the (input) palette case. In png_do_read_transformations
\r
1080 * the first step is to expand the palette if requested, so this code must
\r
1081 * take care to only make changes that are invariant with respect to the
\r
1082 * palette expansion, or only do them if there is no expansion.
\r
1084 * STRIP_ALPHA has already been handled in the caller (by setting num_trans
\r
1087 int input_has_alpha = 0;
\r
1088 int input_has_transparency = 0;
\r
1090 if (png_ptr->num_trans > 0)
\r
1094 /* Ignore if all the entries are opaque (unlikely!) */
\r
1095 for (i=0; i<png_ptr->num_trans; ++i)
\r
1096 if (png_ptr->trans_alpha[i] == 255)
\r
1098 else if (png_ptr->trans_alpha[i] == 0)
\r
1099 input_has_transparency = 1;
\r
1101 input_has_alpha = 1;
\r
1104 /* If no alpha we can optimize. */
\r
1105 if (!input_has_alpha)
\r
1107 /* Any alpha means background and associative alpha processing is
\r
1108 * required, however if the alpha is 0 or 1 throughout OPTIIMIZE_ALPHA
\r
1109 * and ENCODE_ALPHA are irrelevant.
\r
1111 png_ptr->transformations &= ~PNG_ENCODE_ALPHA;
\r
1112 png_ptr->flags &= ~PNG_FLAG_OPTIMIZE_ALPHA;
\r
1114 if (!input_has_transparency)
\r
1115 png_ptr->transformations &= ~(PNG_COMPOSE | PNG_BACKGROUND_EXPAND);
\r
1118 #if defined(PNG_READ_EXPAND_SUPPORTED) && defined(PNG_READ_BACKGROUND_SUPPORTED)
\r
1119 /* png_set_background handling - deals with the complexity of whether the
\r
1120 * background color is in the file format or the screen format in the case
\r
1121 * where an 'expand' will happen.
\r
1124 /* The following code cannot be entered in the alpha pre-multiplication case
\r
1125 * because PNG_BACKGROUND_EXPAND is cancelled below.
\r
1127 if ((png_ptr->transformations & PNG_BACKGROUND_EXPAND) &&
\r
1128 (png_ptr->transformations & PNG_EXPAND))
\r
1131 png_ptr->background.red =
\r
1132 png_ptr->palette[png_ptr->background.index].red;
\r
1133 png_ptr->background.green =
\r
1134 png_ptr->palette[png_ptr->background.index].green;
\r
1135 png_ptr->background.blue =
\r
1136 png_ptr->palette[png_ptr->background.index].blue;
\r
1138 #ifdef PNG_READ_INVERT_ALPHA_SUPPORTED
\r
1139 if (png_ptr->transformations & PNG_INVERT_ALPHA)
\r
1141 if (!(png_ptr->transformations & PNG_EXPAND_tRNS))
\r
1143 /* Invert the alpha channel (in tRNS) unless the pixels are
\r
1144 * going to be expanded, in which case leave it for later
\r
1146 int i, istop = png_ptr->num_trans;
\r
1148 for (i=0; i<istop; i++)
\r
1149 png_ptr->trans_alpha[i] = (png_byte)(255 -
\r
1150 png_ptr->trans_alpha[i]);
\r
1153 #endif /* PNG_READ_INVERT_ALPHA_SUPPORTED */
\r
1155 } /* background expand and (therefore) no alpha association. */
\r
1156 #endif /* PNG_READ_EXPAND_SUPPORTED && PNG_READ_BACKGROUND_SUPPORTED */
\r
1159 static void /* PRIVATE */
\r
1160 png_init_rgb_transformations(png_structp png_ptr)
\r
1162 /* Added to libpng-1.5.4: check the color type to determine whether there
\r
1163 * is any alpha or transparency in the image and simply cancel the
\r
1164 * background and alpha mode stuff if there isn't.
\r
1166 int input_has_alpha = (png_ptr->color_type & PNG_COLOR_MASK_ALPHA) != 0;
\r
1167 int input_has_transparency = png_ptr->num_trans > 0;
\r
1169 /* If no alpha we can optimize. */
\r
1170 if (!input_has_alpha)
\r
1172 /* Any alpha means background and associative alpha processing is
\r
1173 * required, however if the alpha is 0 or 1 throughout OPTIIMIZE_ALPHA
\r
1174 * and ENCODE_ALPHA are irrelevant.
\r
1176 # ifdef PNG_READ_ALPHA_MODE_SUPPORTED
\r
1177 png_ptr->transformations &= ~PNG_ENCODE_ALPHA;
\r
1178 png_ptr->flags &= ~PNG_FLAG_OPTIMIZE_ALPHA;
\r
1181 if (!input_has_transparency)
\r
1182 png_ptr->transformations &= ~(PNG_COMPOSE | PNG_BACKGROUND_EXPAND);
\r
1185 #if defined(PNG_READ_EXPAND_SUPPORTED) && defined(PNG_READ_BACKGROUND_SUPPORTED)
\r
1186 /* png_set_background handling - deals with the complexity of whether the
\r
1187 * background color is in the file format or the screen format in the case
\r
1188 * where an 'expand' will happen.
\r
1191 /* The following code cannot be entered in the alpha pre-multiplication case
\r
1192 * because PNG_BACKGROUND_EXPAND is cancelled below.
\r
1194 if ((png_ptr->transformations & PNG_BACKGROUND_EXPAND) &&
\r
1195 (png_ptr->transformations & PNG_EXPAND) &&
\r
1196 !(png_ptr->color_type & PNG_COLOR_MASK_COLOR))
\r
1197 /* i.e., GRAY or GRAY_ALPHA */
\r
1200 /* Expand background and tRNS chunks */
\r
1201 int gray = png_ptr->background.gray;
\r
1202 int trans_gray = png_ptr->trans_color.gray;
\r
1204 switch (png_ptr->bit_depth)
\r
1208 trans_gray *= 0xff;
\r
1213 trans_gray *= 0x55;
\r
1218 trans_gray *= 0x11;
\r
1224 /* Already 8 bits, fall through */
\r
1227 /* Already a full 16 bits */
\r
1231 png_ptr->background.red = png_ptr->background.green =
\r
1232 png_ptr->background.blue = (png_uint_16)gray;
\r
1234 if (!(png_ptr->transformations & PNG_EXPAND_tRNS))
\r
1236 png_ptr->trans_color.red = png_ptr->trans_color.green =
\r
1237 png_ptr->trans_color.blue = (png_uint_16)trans_gray;
\r
1240 } /* background expand and (therefore) no alpha association. */
\r
1241 #endif /* PNG_READ_EXPAND_SUPPORTED && PNG_READ_BACKGROUND_SUPPORTED */
\r
1244 void /* PRIVATE */
\r
1245 png_init_read_transformations(png_structp png_ptr)
\r
1247 png_debug(1, "in png_init_read_transformations");
\r
1249 /* This internal function is called from png_read_start_row in pngrutil.c
\r
1250 * and it is called before the 'rowbytes' calculation is done, so the code
\r
1251 * in here can change or update the transformations flags.
\r
1253 * First do updates that do not depend on the details of the PNG image data
\r
1254 * being processed.
\r
1257 #ifdef PNG_READ_GAMMA_SUPPORTED
\r
1258 /* Prior to 1.5.4 these tests were performed from png_set_gamma, 1.5.4 adds
\r
1259 * png_set_alpha_mode and this is another source for a default file gamma so
\r
1260 * the test needs to be performed later - here. In addition prior to 1.5.4
\r
1261 * the tests were repeated for the PALETTE color type here - this is no
\r
1262 * longer necessary (and doesn't seem to have been necessary before.)
\r
1265 /* The following temporary indicates if overall gamma correction is
\r
1268 int gamma_correction = 0;
\r
1270 if (png_ptr->gamma != 0) /* has been set */
\r
1272 if (png_ptr->screen_gamma != 0) /* screen set too */
\r
1273 gamma_correction = png_gamma_threshold(png_ptr->gamma,
\r
1274 png_ptr->screen_gamma);
\r
1277 /* Assume the output matches the input; a long time default behavior
\r
1278 * of libpng, although the standard has nothing to say about this.
\r
1280 png_ptr->screen_gamma = png_reciprocal(png_ptr->gamma);
\r
1283 else if (png_ptr->screen_gamma != 0)
\r
1284 /* The converse - assume the file matches the screen, note that this
\r
1285 * perhaps undesireable default can (from 1.5.4) be changed by calling
\r
1286 * png_set_alpha_mode (even if the alpha handling mode isn't required
\r
1287 * or isn't changed from the default.)
\r
1289 png_ptr->gamma = png_reciprocal(png_ptr->screen_gamma);
\r
1291 else /* neither are set */
\r
1292 /* Just in case the following prevents any processing - file and screen
\r
1293 * are both assumed to be linear and there is no way to introduce a
\r
1294 * third gamma value other than png_set_background with 'UNIQUE', and,
\r
1297 png_ptr->screen_gamma = png_ptr->gamma = PNG_FP_1;
\r
1299 /* Now turn the gamma transformation on or off as appropriate. Notice
\r
1300 * that PNG_GAMMA just refers to the file->screen correction. Alpha
\r
1301 * composition may independently cause gamma correction because it needs
\r
1302 * linear data (e.g. if the file has a gAMA chunk but the screen gamma
\r
1303 * hasn't been specified.) In any case this flag may get turned off in
\r
1304 * the code immediately below if the transform can be handled outside the
\r
1307 if (gamma_correction)
\r
1308 png_ptr->transformations |= PNG_GAMMA;
\r
1311 png_ptr->transformations &= ~PNG_GAMMA;
\r
1315 /* Certain transformations have the effect of preventing other
\r
1316 * transformations that happen afterward in png_do_read_transformations,
\r
1317 * resolve the interdependencies here. From the code of
\r
1318 * png_do_read_transformations the order is:
\r
1320 * 1) PNG_EXPAND (including PNG_EXPAND_tRNS)
\r
1321 * 2) PNG_STRIP_ALPHA (if no compose)
\r
1322 * 3) PNG_RGB_TO_GRAY
\r
1323 * 4) PNG_GRAY_TO_RGB iff !PNG_BACKGROUND_IS_GRAY
\r
1326 * 7) PNG_STRIP_ALPHA (if compose)
\r
1327 * 8) PNG_ENCODE_ALPHA
\r
1328 * 9) PNG_SCALE_16_TO_8
\r
1330 * 11) PNG_QUANTIZE (converts to palette)
\r
1331 * 12) PNG_EXPAND_16
\r
1332 * 13) PNG_GRAY_TO_RGB iff PNG_BACKGROUND_IS_GRAY
\r
1333 * 14) PNG_INVERT_MONO
\r
1337 * 18) PNG_PACKSWAP
\r
1338 * 19) PNG_FILLER (includes PNG_ADD_ALPHA)
\r
1339 * 20) PNG_INVERT_ALPHA
\r
1340 * 21) PNG_SWAP_ALPHA
\r
1341 * 22) PNG_SWAP_BYTES
\r
1342 * 23) PNG_USER_TRANSFORM [must be last]
\r
1344 #ifdef PNG_READ_STRIP_ALPHA_SUPPORTED
\r
1345 if ((png_ptr->transformations & PNG_STRIP_ALPHA) &&
\r
1346 !(png_ptr->transformations & PNG_COMPOSE))
\r
1348 /* Stripping the alpha channel happens immediately after the 'expand'
\r
1349 * transformations, before all other transformation, so it cancels out
\r
1350 * the alpha handling. It has the side effect negating the effect of
\r
1351 * PNG_EXPAND_tRNS too:
\r
1353 png_ptr->transformations &= ~(PNG_BACKGROUND_EXPAND | PNG_ENCODE_ALPHA |
\r
1355 png_ptr->flags &= ~PNG_FLAG_OPTIMIZE_ALPHA;
\r
1357 /* Kill the tRNS chunk itself too. Prior to 1.5.4 this did not happen
\r
1358 * so transparency information would remain just so long as it wasn't
\r
1359 * expanded. This produces unexpected API changes if the set of things
\r
1360 * that do PNG_EXPAND_tRNS changes (perfectly possible given the
\r
1361 * documentation - which says ask for what you want, accept what you
\r
1362 * get.) This makes the behavior consistent from 1.5.4:
\r
1364 png_ptr->num_trans = 0;
\r
1366 #endif /* STRIP_ALPHA supported, no COMPOSE */
\r
1368 #ifdef PNG_READ_ALPHA_MODE_SUPPORTED
\r
1369 /* If the screen gamma is about 1.0 then the OPTIMIZE_ALPHA and ENCODE_ALPHA
\r
1370 * settings will have no effect.
\r
1372 if (!png_gamma_significant(png_ptr->screen_gamma))
\r
1374 png_ptr->transformations &= ~PNG_ENCODE_ALPHA;
\r
1375 png_ptr->flags &= ~PNG_FLAG_OPTIMIZE_ALPHA;
\r
1379 #if defined(PNG_READ_EXPAND_SUPPORTED) && \
\r
1380 defined(PNG_READ_BACKGROUND_SUPPORTED) && \
\r
1381 defined(PNG_READ_GRAY_TO_RGB_SUPPORTED)
\r
1382 /* Detect gray background and attempt to enable optimization for
\r
1383 * gray --> RGB case.
\r
1385 * Note: if PNG_BACKGROUND_EXPAND is set and color_type is either RGB or
\r
1386 * RGB_ALPHA (in which case need_expand is superfluous anyway), the
\r
1387 * background color might actually be gray yet not be flagged as such.
\r
1388 * This is not a problem for the current code, which uses
\r
1389 * PNG_BACKGROUND_IS_GRAY only to decide when to do the
\r
1390 * png_do_gray_to_rgb() transformation.
\r
1392 * TODO: this code needs to be revised to avoid the complexity and
\r
1393 * interdependencies. The color type of the background should be recorded in
\r
1394 * png_set_background, along with the bit depth, then the code has a record
\r
1395 * of exactly what color space the background is currently in.
\r
1397 if (png_ptr->transformations & PNG_BACKGROUND_EXPAND)
\r
1399 /* PNG_BACKGROUND_EXPAND: the background is in the file color space, so if
\r
1400 * the file was grayscale the background value is gray.
\r
1402 if (!(png_ptr->color_type & PNG_COLOR_MASK_COLOR))
\r
1403 png_ptr->mode |= PNG_BACKGROUND_IS_GRAY;
\r
1406 else if (png_ptr->transformations & PNG_COMPOSE)
\r
1408 /* PNG_COMPOSE: png_set_background was called with need_expand false,
\r
1409 * so the color is in the color space of the output or png_set_alpha_mode
\r
1410 * was called and the color is black. Ignore RGB_TO_GRAY because that
\r
1411 * happens before GRAY_TO_RGB.
\r
1413 if (png_ptr->transformations & PNG_GRAY_TO_RGB)
\r
1415 if (png_ptr->background.red == png_ptr->background.green &&
\r
1416 png_ptr->background.red == png_ptr->background.blue)
\r
1418 png_ptr->mode |= PNG_BACKGROUND_IS_GRAY;
\r
1419 png_ptr->background.gray = png_ptr->background.red;
\r
1423 #endif /* PNG_READ_GRAY_TO_RGB_SUPPORTED (etc) */
\r
1425 /* For indexed PNG data (PNG_COLOR_TYPE_PALETTE) many of the transformations
\r
1426 * can be performed directly on the palette, and some (such as rgb to gray)
\r
1427 * can be optimized inside the palette. This is particularly true of the
\r
1428 * composite (background and alpha) stuff, which can be pretty much all done
\r
1429 * in the palette even if the result is expanded to RGB or gray afterward.
\r
1431 * NOTE: this is Not Yet Implemented, the code behaves as in 1.5.1 and
\r
1432 * earlier and the palette stuff is actually handled on the first row. This
\r
1433 * leads to the reported bug that the palette returned by png_get_PLTE is not
\r
1436 if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE)
\r
1437 png_init_palette_transformations(png_ptr);
\r
1440 png_init_rgb_transformations(png_ptr);
\r
1442 #if defined(PNG_READ_BACKGROUND_SUPPORTED) && \
\r
1443 defined(PNG_READ_EXPAND_16_SUPPORTED)
\r
1444 if ((png_ptr->transformations & PNG_EXPAND_16) &&
\r
1445 (png_ptr->transformations & PNG_COMPOSE) &&
\r
1446 !(png_ptr->transformations & PNG_BACKGROUND_EXPAND) &&
\r
1447 png_ptr->bit_depth != 16)
\r
1449 /* TODO: fix this. Because the expand_16 operation is after the compose
\r
1450 * handling the background color must be 8, not 16, bits deep, but the
\r
1451 * application will supply a 16-bit value so reduce it here.
\r
1453 * The PNG_BACKGROUND_EXPAND code above does not expand to 16 bits at
\r
1454 * present, so that case is ok (until do_expand_16 is moved.)
\r
1456 * NOTE: this discards the low 16 bits of the user supplied background
\r
1457 * color, but until expand_16 works properly there is no choice!
\r
1459 # define CHOP(x) (x)=((png_uint_16)(((png_uint_32)(x)*255+32895) >> 16))
\r
1460 CHOP(png_ptr->background.red);
\r
1461 CHOP(png_ptr->background.green);
\r
1462 CHOP(png_ptr->background.blue);
\r
1463 CHOP(png_ptr->background.gray);
\r
1466 #endif /* PNG_READ_BACKGROUND_SUPPORTED && PNG_READ_EXPAND_16_SUPPORTED */
\r
1468 #if defined(PNG_READ_BACKGROUND_SUPPORTED) && \
\r
1469 (defined(PNG_READ_SCALE_16_TO_8_SUPPORTED) || \
\r
1470 defined(PNG_READ_STRIP_16_TO_8_SUPPORTED))
\r
1471 if ((png_ptr->transformations & (PNG_16_TO_8|PNG_SCALE_16_TO_8)) &&
\r
1472 (png_ptr->transformations & PNG_COMPOSE) &&
\r
1473 !(png_ptr->transformations & PNG_BACKGROUND_EXPAND) &&
\r
1474 png_ptr->bit_depth == 16)
\r
1476 /* On the other hand, if a 16-bit file is to be reduced to 8-bits per
\r
1477 * component this will also happen after PNG_COMPOSE and so the background
\r
1478 * color must be pre-expanded here.
\r
1480 * TODO: fix this too.
\r
1482 png_ptr->background.red = (png_uint_16)(png_ptr->background.red * 257);
\r
1483 png_ptr->background.green =
\r
1484 (png_uint_16)(png_ptr->background.green * 257);
\r
1485 png_ptr->background.blue = (png_uint_16)(png_ptr->background.blue * 257);
\r
1486 png_ptr->background.gray = (png_uint_16)(png_ptr->background.gray * 257);
\r
1490 /* NOTE: below 'PNG_READ_ALPHA_MODE_SUPPORTED' is presumed to also enable the
\r
1491 * background support (see the comments in scripts/pnglibconf.dfa), this
\r
1492 * allows pre-multiplication of the alpha channel to be implemented as
\r
1493 * compositing on black. This is probably sub-optimal and has been done in
\r
1494 * 1.5.4 betas simply to enable external critique and testing (i.e. to
\r
1495 * implement the new API quickly, without lots of internal changes.)
\r
1498 #ifdef PNG_READ_GAMMA_SUPPORTED
\r
1499 # ifdef PNG_READ_BACKGROUND_SUPPORTED
\r
1500 /* Includes ALPHA_MODE */
\r
1501 png_ptr->background_1 = png_ptr->background;
\r
1504 /* This needs to change - in the palette image case a whole set of tables are
\r
1505 * built when it would be quicker to just calculate the correct value for
\r
1506 * each palette entry directly. Also, the test is too tricky - why check
\r
1507 * PNG_RGB_TO_GRAY if PNG_GAMMA is not set? The answer seems to be that
\r
1508 * PNG_GAMMA is cancelled even if the gamma is known? The test excludes the
\r
1509 * PNG_COMPOSE case, so apparently if there is no *overall* gamma correction
\r
1510 * the gamma tables will not be built even if composition is required on a
\r
1511 * gamma encoded value.
\r
1513 * In 1.5.4 this is addressed below by an additional check on the individual
\r
1514 * file gamma - if it is not 1.0 both RGB_TO_GRAY and COMPOSE need the
\r
1517 if ((png_ptr->transformations & PNG_GAMMA)
\r
1518 || ((png_ptr->transformations & PNG_RGB_TO_GRAY)
\r
1519 && (png_gamma_significant(png_ptr->gamma) ||
\r
1520 png_gamma_significant(png_ptr->screen_gamma)))
\r
1521 || ((png_ptr->transformations & PNG_COMPOSE)
\r
1522 && (png_gamma_significant(png_ptr->gamma)
\r
1523 || png_gamma_significant(png_ptr->screen_gamma)
\r
1524 # ifdef PNG_READ_BACKGROUND_SUPPORTED
\r
1525 || (png_ptr->background_gamma_type == PNG_BACKGROUND_GAMMA_UNIQUE
\r
1526 && png_gamma_significant(png_ptr->background_gamma))
\r
1528 )) || ((png_ptr->transformations & PNG_ENCODE_ALPHA)
\r
1529 && png_gamma_significant(png_ptr->screen_gamma))
\r
1532 png_build_gamma_table(png_ptr, png_ptr->bit_depth);
\r
1534 #ifdef PNG_READ_BACKGROUND_SUPPORTED
\r
1535 if (png_ptr->transformations & PNG_COMPOSE)
\r
1537 /* Issue a warning about this combination: because RGB_TO_GRAY is
\r
1538 * optimized to do the gamma transform if present yet do_background has
\r
1539 * to do the same thing if both options are set a
\r
1540 * double-gamma-correction happens. This is true in all versions of
\r
1543 if (png_ptr->transformations & PNG_RGB_TO_GRAY)
\r
1544 png_warning(png_ptr,
\r
1545 "libpng does not support gamma+background+rgb_to_gray");
\r
1547 if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE)
\r
1549 /* We don't get to here unless there is a tRNS chunk with non-opaque
\r
1550 * entries - see the checking code at the start of this function.
\r
1552 png_color back, back_1;
\r
1553 png_colorp palette = png_ptr->palette;
\r
1554 int num_palette = png_ptr->num_palette;
\r
1556 if (png_ptr->background_gamma_type == PNG_BACKGROUND_GAMMA_FILE)
\r
1559 back.red = png_ptr->gamma_table[png_ptr->background.red];
\r
1560 back.green = png_ptr->gamma_table[png_ptr->background.green];
\r
1561 back.blue = png_ptr->gamma_table[png_ptr->background.blue];
\r
1563 back_1.red = png_ptr->gamma_to_1[png_ptr->background.red];
\r
1564 back_1.green = png_ptr->gamma_to_1[png_ptr->background.green];
\r
1565 back_1.blue = png_ptr->gamma_to_1[png_ptr->background.blue];
\r
1569 png_fixed_point g, gs;
\r
1571 switch (png_ptr->background_gamma_type)
\r
1573 case PNG_BACKGROUND_GAMMA_SCREEN:
\r
1574 g = (png_ptr->screen_gamma);
\r
1578 case PNG_BACKGROUND_GAMMA_FILE:
\r
1579 g = png_reciprocal(png_ptr->gamma);
\r
1580 gs = png_reciprocal2(png_ptr->gamma,
\r
1581 png_ptr->screen_gamma);
\r
1584 case PNG_BACKGROUND_GAMMA_UNIQUE:
\r
1585 g = png_reciprocal(png_ptr->background_gamma);
\r
1586 gs = png_reciprocal2(png_ptr->background_gamma,
\r
1587 png_ptr->screen_gamma);
\r
1590 g = PNG_FP_1; /* back_1 */
\r
1591 gs = PNG_FP_1; /* back */
\r
1595 if (png_gamma_significant(gs))
\r
1597 back.red = png_gamma_8bit_correct(png_ptr->background.red,
\r
1599 back.green = png_gamma_8bit_correct(png_ptr->background.green,
\r
1601 back.blue = png_gamma_8bit_correct(png_ptr->background.blue,
\r
1607 back.red = (png_byte)png_ptr->background.red;
\r
1608 back.green = (png_byte)png_ptr->background.green;
\r
1609 back.blue = (png_byte)png_ptr->background.blue;
\r
1612 if (png_gamma_significant(g))
\r
1614 back_1.red = png_gamma_8bit_correct(png_ptr->background.red,
\r
1616 back_1.green = png_gamma_8bit_correct(
\r
1617 png_ptr->background.green, g);
\r
1618 back_1.blue = png_gamma_8bit_correct(png_ptr->background.blue,
\r
1624 back_1.red = (png_byte)png_ptr->background.red;
\r
1625 back_1.green = (png_byte)png_ptr->background.green;
\r
1626 back_1.blue = (png_byte)png_ptr->background.blue;
\r
1630 for (i = 0; i < num_palette; i++)
\r
1632 if (i < (int)png_ptr->num_trans &&
\r
1633 png_ptr->trans_alpha[i] != 0xff)
\r
1635 if (png_ptr->trans_alpha[i] == 0)
\r
1637 palette[i] = back;
\r
1639 else /* if (png_ptr->trans_alpha[i] != 0xff) */
\r
1643 v = png_ptr->gamma_to_1[palette[i].red];
\r
1644 png_composite(w, v, png_ptr->trans_alpha[i], back_1.red);
\r
1645 palette[i].red = png_ptr->gamma_from_1[w];
\r
1647 v = png_ptr->gamma_to_1[palette[i].green];
\r
1648 png_composite(w, v, png_ptr->trans_alpha[i], back_1.green);
\r
1649 palette[i].green = png_ptr->gamma_from_1[w];
\r
1651 v = png_ptr->gamma_to_1[palette[i].blue];
\r
1652 png_composite(w, v, png_ptr->trans_alpha[i], back_1.blue);
\r
1653 palette[i].blue = png_ptr->gamma_from_1[w];
\r
1658 palette[i].red = png_ptr->gamma_table[palette[i].red];
\r
1659 palette[i].green = png_ptr->gamma_table[palette[i].green];
\r
1660 palette[i].blue = png_ptr->gamma_table[palette[i].blue];
\r
1664 /* Prevent the transformations being done again.
\r
1666 * NOTE: this is highly dubious; it removes the transformations in
\r
1667 * place. This seems inconsistent with the general treatment of the
\r
1668 * transformations elsewhere.
\r
1670 png_ptr->transformations &= ~(PNG_COMPOSE | PNG_GAMMA);
\r
1671 } /* color_type == PNG_COLOR_TYPE_PALETTE */
\r
1673 /* if (png_ptr->background_gamma_type!=PNG_BACKGROUND_GAMMA_UNKNOWN) */
\r
1674 else /* color_type != PNG_COLOR_TYPE_PALETTE */
\r
1676 int gs_sig, g_sig;
\r
1677 png_fixed_point g = PNG_FP_1; /* Correction to linear */
\r
1678 png_fixed_point gs = PNG_FP_1; /* Correction to screen */
\r
1680 switch (png_ptr->background_gamma_type)
\r
1682 case PNG_BACKGROUND_GAMMA_SCREEN:
\r
1683 g = png_ptr->screen_gamma;
\r
1684 /* gs = PNG_FP_1; */
\r
1687 case PNG_BACKGROUND_GAMMA_FILE:
\r
1688 g = png_reciprocal(png_ptr->gamma);
\r
1689 gs = png_reciprocal2(png_ptr->gamma, png_ptr->screen_gamma);
\r
1692 case PNG_BACKGROUND_GAMMA_UNIQUE:
\r
1693 g = png_reciprocal(png_ptr->background_gamma);
\r
1694 gs = png_reciprocal2(png_ptr->background_gamma,
\r
1695 png_ptr->screen_gamma);
\r
1699 png_error(png_ptr, "invalid background gamma type");
\r
1702 g_sig = png_gamma_significant(g);
\r
1703 gs_sig = png_gamma_significant(gs);
\r
1706 png_ptr->background_1.gray = png_gamma_correct(png_ptr,
\r
1707 png_ptr->background.gray, g);
\r
1710 png_ptr->background.gray = png_gamma_correct(png_ptr,
\r
1711 png_ptr->background.gray, gs);
\r
1713 if ((png_ptr->background.red != png_ptr->background.green) ||
\r
1714 (png_ptr->background.red != png_ptr->background.blue) ||
\r
1715 (png_ptr->background.red != png_ptr->background.gray))
\r
1717 /* RGB or RGBA with color background */
\r
1720 png_ptr->background_1.red = png_gamma_correct(png_ptr,
\r
1721 png_ptr->background.red, g);
\r
1723 png_ptr->background_1.green = png_gamma_correct(png_ptr,
\r
1724 png_ptr->background.green, g);
\r
1726 png_ptr->background_1.blue = png_gamma_correct(png_ptr,
\r
1727 png_ptr->background.blue, g);
\r
1732 png_ptr->background.red = png_gamma_correct(png_ptr,
\r
1733 png_ptr->background.red, gs);
\r
1735 png_ptr->background.green = png_gamma_correct(png_ptr,
\r
1736 png_ptr->background.green, gs);
\r
1738 png_ptr->background.blue = png_gamma_correct(png_ptr,
\r
1739 png_ptr->background.blue, gs);
\r
1745 /* GRAY, GRAY ALPHA, RGB, or RGBA with gray background */
\r
1746 png_ptr->background_1.red = png_ptr->background_1.green
\r
1747 = png_ptr->background_1.blue = png_ptr->background_1.gray;
\r
1749 png_ptr->background.red = png_ptr->background.green
\r
1750 = png_ptr->background.blue = png_ptr->background.gray;
\r
1753 /* The background is now in screen gamma: */
\r
1754 png_ptr->background_gamma_type = PNG_BACKGROUND_GAMMA_SCREEN;
\r
1755 } /* color_type != PNG_COLOR_TYPE_PALETTE */
\r
1756 }/* png_ptr->transformations & PNG_BACKGROUND */
\r
1759 /* Transformation does not include PNG_BACKGROUND */
\r
1760 #endif /* PNG_READ_BACKGROUND_SUPPORTED */
\r
1761 if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE
\r
1762 #ifdef PNG_READ_RGB_TO_GRAY_SUPPORTED
\r
1763 /* RGB_TO_GRAY needs to have non-gamma-corrected values! */
\r
1764 && ((png_ptr->transformations & PNG_EXPAND) == 0 ||
\r
1765 (png_ptr->transformations & PNG_RGB_TO_GRAY) == 0)
\r
1769 png_colorp palette = png_ptr->palette;
\r
1770 int num_palette = png_ptr->num_palette;
\r
1773 /*NOTE: there are other transformations that should probably be in here
\r
1776 for (i = 0; i < num_palette; i++)
\r
1778 palette[i].red = png_ptr->gamma_table[palette[i].red];
\r
1779 palette[i].green = png_ptr->gamma_table[palette[i].green];
\r
1780 palette[i].blue = png_ptr->gamma_table[palette[i].blue];
\r
1783 /* Done the gamma correction. */
\r
1784 png_ptr->transformations &= ~PNG_GAMMA;
\r
1785 } /* color_type == PALETTE && !PNG_BACKGROUND transformation */
\r
1787 #ifdef PNG_READ_BACKGROUND_SUPPORTED
\r
1790 #endif /* PNG_READ_GAMMA_SUPPORTED */
\r
1792 #ifdef PNG_READ_BACKGROUND_SUPPORTED
\r
1793 /* No GAMMA transformation (see the hanging else 4 lines above) */
\r
1794 if ((png_ptr->transformations & PNG_COMPOSE) &&
\r
1795 (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE))
\r
1798 int istop = (int)png_ptr->num_trans;
\r
1800 png_colorp palette = png_ptr->palette;
\r
1802 back.red = (png_byte)png_ptr->background.red;
\r
1803 back.green = (png_byte)png_ptr->background.green;
\r
1804 back.blue = (png_byte)png_ptr->background.blue;
\r
1806 for (i = 0; i < istop; i++)
\r
1808 if (png_ptr->trans_alpha[i] == 0)
\r
1810 palette[i] = back;
\r
1813 else if (png_ptr->trans_alpha[i] != 0xff)
\r
1815 /* The png_composite() macro is defined in png.h */
\r
1816 png_composite(palette[i].red, palette[i].red,
\r
1817 png_ptr->trans_alpha[i], back.red);
\r
1819 png_composite(palette[i].green, palette[i].green,
\r
1820 png_ptr->trans_alpha[i], back.green);
\r
1822 png_composite(palette[i].blue, palette[i].blue,
\r
1823 png_ptr->trans_alpha[i], back.blue);
\r
1827 png_ptr->transformations &= ~PNG_COMPOSE;
\r
1829 #endif /* PNG_READ_BACKGROUND_SUPPORTED */
\r
1831 #ifdef PNG_READ_SHIFT_SUPPORTED
\r
1832 if ((png_ptr->transformations & PNG_SHIFT) &&
\r
1833 (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE))
\r
1836 int istop = png_ptr->num_palette;
\r
1837 int shift = 8 - png_ptr->sig_bit.red;
\r
1839 /* significant bits can be in the range 1 to 7 for a meaninful result, if
\r
1840 * the number of significant bits is 0 then no shift is done (this is an
\r
1841 * error condition which is silently ignored.)
\r
1843 if (shift > 0 && shift < 8) for (i=0; i<istop; ++i)
\r
1845 int component = png_ptr->palette[i].red;
\r
1847 component >>= shift;
\r
1848 png_ptr->palette[i].red = (png_byte)component;
\r
1851 shift = 8 - png_ptr->sig_bit.green;
\r
1852 if (shift > 0 && shift < 8) for (i=0; i<istop; ++i)
\r
1854 int component = png_ptr->palette[i].green;
\r
1856 component >>= shift;
\r
1857 png_ptr->palette[i].green = (png_byte)component;
\r
1860 shift = 8 - png_ptr->sig_bit.blue;
\r
1861 if (shift > 0 && shift < 8) for (i=0; i<istop; ++i)
\r
1863 int component = png_ptr->palette[i].blue;
\r
1865 component >>= shift;
\r
1866 png_ptr->palette[i].blue = (png_byte)component;
\r
1869 #endif /* PNG_READ_SHIFT_SUPPORTED */
\r
1872 /* Modify the info structure to reflect the transformations. The
\r
1873 * info should be updated so a PNG file could be written with it,
\r
1874 * assuming the transformations result in valid PNG data.
\r
1876 void /* PRIVATE */
\r
1877 png_read_transform_info(png_structp png_ptr, png_infop info_ptr)
\r
1879 png_debug(1, "in png_read_transform_info");
\r
1881 #ifdef PNG_READ_EXPAND_SUPPORTED
\r
1882 if (png_ptr->transformations & PNG_EXPAND)
\r
1884 if (info_ptr->color_type == PNG_COLOR_TYPE_PALETTE)
\r
1886 /* This check must match what actually happens in
\r
1887 * png_do_expand_palette; if it ever checks the tRNS chunk to see if
\r
1888 * it is all opaque we must do the same (at present it does not.)
\r
1890 if (png_ptr->num_trans > 0)
\r
1891 info_ptr->color_type = PNG_COLOR_TYPE_RGB_ALPHA;
\r
1894 info_ptr->color_type = PNG_COLOR_TYPE_RGB;
\r
1896 info_ptr->bit_depth = 8;
\r
1897 info_ptr->num_trans = 0;
\r
1901 if (png_ptr->num_trans)
\r
1903 if (png_ptr->transformations & PNG_EXPAND_tRNS)
\r
1904 info_ptr->color_type |= PNG_COLOR_MASK_ALPHA;
\r
1906 if (info_ptr->bit_depth < 8)
\r
1907 info_ptr->bit_depth = 8;
\r
1909 info_ptr->num_trans = 0;
\r
1914 #if defined(PNG_READ_BACKGROUND_SUPPORTED) ||\
\r
1915 defined(PNG_READ_ALPHA_MODE_SUPPORTED)
\r
1916 /* The following is almost certainly wrong unless the background value is in
\r
1917 * the screen space!
\r
1919 if (png_ptr->transformations & PNG_COMPOSE)
\r
1920 info_ptr->background = png_ptr->background;
\r
1923 #ifdef PNG_READ_GAMMA_SUPPORTED
\r
1924 /* The following used to be conditional on PNG_GAMMA (prior to 1.5.4),
\r
1925 * however it seems that the code in png_init_read_transformations, which has
\r
1926 * been called before this from png_read_update_info->png_read_start_row
\r
1927 * sometimes does the gamma transform and cancels the flag.
\r
1929 info_ptr->gamma = png_ptr->gamma;
\r
1932 if (info_ptr->bit_depth == 16)
\r
1934 # ifdef PNG_READ_16BIT_SUPPORTED
\r
1935 # ifdef PNG_READ_SCALE_16_TO_8_SUPPORTED
\r
1936 if (png_ptr->transformations & PNG_SCALE_16_TO_8)
\r
1937 info_ptr->bit_depth = 8;
\r
1940 # ifdef PNG_READ_STRIP_16_TO_8_SUPPORTED
\r
1941 if (png_ptr->transformations & PNG_16_TO_8)
\r
1942 info_ptr->bit_depth = 8;
\r
1946 /* No 16 bit support: force chopping 16-bit input down to 8, in this case
\r
1947 * the app program can chose if both APIs are available by setting the
\r
1948 * correct scaling to use.
\r
1950 # ifdef PNG_READ_STRIP_16_TO_8_SUPPORTED
\r
1951 /* For compatibility with previous versions use the strip method by
\r
1952 * default. This code works because if PNG_SCALE_16_TO_8 is already
\r
1953 * set the code below will do that in preference to the chop.
\r
1955 png_ptr->transformations |= PNG_16_TO_8;
\r
1956 info_ptr->bit_depth = 8;
\r
1959 # ifdef PNG_READ_SCALE_16_TO_8_SUPPORTED
\r
1960 png_ptr->transformations |= PNG_SCALE_16_TO_8;
\r
1961 info_ptr->bit_depth = 8;
\r
1964 CONFIGURATION ERROR: you must enable at least one 16 to 8 method
\r
1967 #endif /* !READ_16BIT_SUPPORTED */
\r
1970 #ifdef PNG_READ_GRAY_TO_RGB_SUPPORTED
\r
1971 if (png_ptr->transformations & PNG_GRAY_TO_RGB)
\r
1972 info_ptr->color_type = (png_byte)(info_ptr->color_type |
\r
1973 PNG_COLOR_MASK_COLOR);
\r
1976 #ifdef PNG_READ_RGB_TO_GRAY_SUPPORTED
\r
1977 if (png_ptr->transformations & PNG_RGB_TO_GRAY)
\r
1978 info_ptr->color_type = (png_byte)(info_ptr->color_type &
\r
1979 ~PNG_COLOR_MASK_COLOR);
\r
1982 #ifdef PNG_READ_QUANTIZE_SUPPORTED
\r
1983 if (png_ptr->transformations & PNG_QUANTIZE)
\r
1985 if (((info_ptr->color_type == PNG_COLOR_TYPE_RGB) ||
\r
1986 (info_ptr->color_type == PNG_COLOR_TYPE_RGB_ALPHA)) &&
\r
1987 png_ptr->palette_lookup && info_ptr->bit_depth == 8)
\r
1989 info_ptr->color_type = PNG_COLOR_TYPE_PALETTE;
\r
1994 #ifdef PNG_READ_EXPAND_16_SUPPORTED
\r
1995 if (png_ptr->transformations & PNG_EXPAND_16 && info_ptr->bit_depth == 8 &&
\r
1996 info_ptr->color_type != PNG_COLOR_TYPE_PALETTE)
\r
1998 info_ptr->bit_depth = 16;
\r
2002 #ifdef PNG_READ_PACK_SUPPORTED
\r
2003 if ((png_ptr->transformations & PNG_PACK) && (info_ptr->bit_depth < 8))
\r
2004 info_ptr->bit_depth = 8;
\r
2007 if (info_ptr->color_type == PNG_COLOR_TYPE_PALETTE)
\r
2008 info_ptr->channels = 1;
\r
2010 else if (info_ptr->color_type & PNG_COLOR_MASK_COLOR)
\r
2011 info_ptr->channels = 3;
\r
2014 info_ptr->channels = 1;
\r
2016 #ifdef PNG_READ_STRIP_ALPHA_SUPPORTED
\r
2017 if (png_ptr->transformations & PNG_STRIP_ALPHA)
\r
2019 info_ptr->color_type = (png_byte)(info_ptr->color_type &
\r
2020 ~PNG_COLOR_MASK_ALPHA);
\r
2021 info_ptr->num_trans = 0;
\r
2025 if (info_ptr->color_type & PNG_COLOR_MASK_ALPHA)
\r
2026 info_ptr->channels++;
\r
2028 #ifdef PNG_READ_FILLER_SUPPORTED
\r
2029 /* STRIP_ALPHA and FILLER allowed: MASK_ALPHA bit stripped above */
\r
2030 if ((png_ptr->transformations & PNG_FILLER) &&
\r
2031 ((info_ptr->color_type == PNG_COLOR_TYPE_RGB) ||
\r
2032 (info_ptr->color_type == PNG_COLOR_TYPE_GRAY)))
\r
2034 info_ptr->channels++;
\r
2035 /* If adding a true alpha channel not just filler */
\r
2036 if (png_ptr->transformations & PNG_ADD_ALPHA)
\r
2037 info_ptr->color_type |= PNG_COLOR_MASK_ALPHA;
\r
2041 #if defined(PNG_USER_TRANSFORM_PTR_SUPPORTED) && \
\r
2042 defined(PNG_READ_USER_TRANSFORM_SUPPORTED)
\r
2043 if (png_ptr->transformations & PNG_USER_TRANSFORM)
\r
2045 if (info_ptr->bit_depth < png_ptr->user_transform_depth)
\r
2046 info_ptr->bit_depth = png_ptr->user_transform_depth;
\r
2048 if (info_ptr->channels < png_ptr->user_transform_channels)
\r
2049 info_ptr->channels = png_ptr->user_transform_channels;
\r
2053 info_ptr->pixel_depth = (png_byte)(info_ptr->channels *
\r
2054 info_ptr->bit_depth);
\r
2056 info_ptr->rowbytes = PNG_ROWBYTES(info_ptr->pixel_depth, info_ptr->width);
\r
2058 /* Adding in 1.5.4: cache the above value in png_struct so that we can later
\r
2059 * check in png_rowbytes that the user buffer won't get overwritten. Note
\r
2060 * that the field is not always set - if png_read_update_info isn't called
\r
2061 * the application has to either not do any transforms or get the calculation
\r
2064 png_ptr->info_rowbytes = info_ptr->rowbytes;
\r
2066 #ifndef PNG_READ_EXPAND_SUPPORTED
\r
2072 /* Transform the row. The order of transformations is significant,
\r
2073 * and is very touchy. If you add a transformation, take care to
\r
2074 * decide how it fits in with the other transformations here.
\r
2076 void /* PRIVATE */
\r
2077 png_do_read_transformations(png_structp png_ptr, png_row_infop row_info)
\r
2079 png_debug(1, "in png_do_read_transformations");
\r
2081 if (png_ptr->row_buf == NULL)
\r
2083 /* Prior to 1.5.4 this output row/pass where the NULL pointer is, but this
\r
2084 * error is incredibly rare and incredibly easy to debug without this
\r
2087 png_error(png_ptr, "NULL row buffer");
\r
2090 /* The following is debugging; prior to 1.5.4 the code was never compiled in;
\r
2091 * in 1.5.4 PNG_FLAG_DETECT_UNINITIALIZED was added and the macro
\r
2092 * PNG_WARN_UNINITIALIZED_ROW removed. In 1.5 the new flag is set only for
\r
2093 * selected new APIs to ensure that there is no API change.
\r
2095 if ((png_ptr->flags & PNG_FLAG_DETECT_UNINITIALIZED) != 0 &&
\r
2096 !(png_ptr->flags & PNG_FLAG_ROW_INIT))
\r
2098 /* Application has failed to call either png_read_start_image() or
\r
2099 * png_read_update_info() after setting transforms that expand pixels.
\r
2100 * This check added to libpng-1.2.19 (but not enabled until 1.5.4).
\r
2102 png_error(png_ptr, "Uninitialized row");
\r
2105 #ifdef PNG_READ_EXPAND_SUPPORTED
\r
2106 if (png_ptr->transformations & PNG_EXPAND)
\r
2108 if (row_info->color_type == PNG_COLOR_TYPE_PALETTE)
\r
2110 png_do_expand_palette(row_info, png_ptr->row_buf + 1,
\r
2111 png_ptr->palette, png_ptr->trans_alpha, png_ptr->num_trans);
\r
2116 if (png_ptr->num_trans &&
\r
2117 (png_ptr->transformations & PNG_EXPAND_tRNS))
\r
2118 png_do_expand(row_info, png_ptr->row_buf + 1,
\r
2119 &(png_ptr->trans_color));
\r
2122 png_do_expand(row_info, png_ptr->row_buf + 1,
\r
2128 #ifdef PNG_READ_STRIP_ALPHA_SUPPORTED
\r
2129 if ((png_ptr->transformations & PNG_STRIP_ALPHA) &&
\r
2130 !(png_ptr->transformations & PNG_COMPOSE) &&
\r
2131 (row_info->color_type == PNG_COLOR_TYPE_RGB_ALPHA ||
\r
2132 row_info->color_type == PNG_COLOR_TYPE_GRAY_ALPHA))
\r
2133 png_do_strip_channel(row_info, png_ptr->row_buf + 1,
\r
2134 0 /* at_start == false, because SWAP_ALPHA happens later */);
\r
2137 #ifdef PNG_READ_RGB_TO_GRAY_SUPPORTED
\r
2138 if (png_ptr->transformations & PNG_RGB_TO_GRAY)
\r
2141 png_do_rgb_to_gray(png_ptr, row_info,
\r
2142 png_ptr->row_buf + 1);
\r
2146 png_ptr->rgb_to_gray_status=1;
\r
2147 if ((png_ptr->transformations & PNG_RGB_TO_GRAY) ==
\r
2148 PNG_RGB_TO_GRAY_WARN)
\r
2149 png_warning(png_ptr, "png_do_rgb_to_gray found nongray pixel");
\r
2151 if ((png_ptr->transformations & PNG_RGB_TO_GRAY) ==
\r
2152 PNG_RGB_TO_GRAY_ERR)
\r
2153 png_error(png_ptr, "png_do_rgb_to_gray found nongray pixel");
\r
2158 /* From Andreas Dilger e-mail to png-implement, 26 March 1998:
\r
2160 * In most cases, the "simple transparency" should be done prior to doing
\r
2161 * gray-to-RGB, or you will have to test 3x as many bytes to check if a
\r
2162 * pixel is transparent. You would also need to make sure that the
\r
2163 * transparency information is upgraded to RGB.
\r
2165 * To summarize, the current flow is:
\r
2166 * - Gray + simple transparency -> compare 1 or 2 gray bytes and composite
\r
2167 * with background "in place" if transparent,
\r
2168 * convert to RGB if necessary
\r
2169 * - Gray + alpha -> composite with gray background and remove alpha bytes,
\r
2170 * convert to RGB if necessary
\r
2172 * To support RGB backgrounds for gray images we need:
\r
2173 * - Gray + simple transparency -> convert to RGB + simple transparency,
\r
2174 * compare 3 or 6 bytes and composite with
\r
2175 * background "in place" if transparent
\r
2176 * (3x compare/pixel compared to doing
\r
2177 * composite with gray bkgrnd)
\r
2178 * - Gray + alpha -> convert to RGB + alpha, composite with background and
\r
2179 * remove alpha bytes (3x float
\r
2180 * operations/pixel compared with composite
\r
2181 * on gray background)
\r
2183 * Greg's change will do this. The reason it wasn't done before is for
\r
2184 * performance, as this increases the per-pixel operations. If we would check
\r
2185 * in advance if the background was gray or RGB, and position the gray-to-RGB
\r
2186 * transform appropriately, then it would save a lot of work/time.
\r
2189 #ifdef PNG_READ_GRAY_TO_RGB_SUPPORTED
\r
2190 /* If gray -> RGB, do so now only if background is non-gray; else do later
\r
2191 * for performance reasons
\r
2193 if ((png_ptr->transformations & PNG_GRAY_TO_RGB) &&
\r
2194 !(png_ptr->mode & PNG_BACKGROUND_IS_GRAY))
\r
2195 png_do_gray_to_rgb(row_info, png_ptr->row_buf + 1);
\r
2198 #if (defined PNG_READ_BACKGROUND_SUPPORTED) ||\
\r
2199 (defined PNG_READ_ALPHA_MODE_SUPPORTED)
\r
2200 if (png_ptr->transformations & PNG_COMPOSE)
\r
2201 png_do_compose(row_info, png_ptr->row_buf + 1, png_ptr);
\r
2204 #ifdef PNG_READ_GAMMA_SUPPORTED
\r
2205 if ((png_ptr->transformations & PNG_GAMMA) &&
\r
2206 #ifdef PNG_READ_RGB_TO_GRAY_SUPPORTED
\r
2207 /* Because RGB_TO_GRAY does the gamma transform. */
\r
2208 !(png_ptr->transformations & PNG_RGB_TO_GRAY) &&
\r
2210 #if (defined PNG_READ_BACKGROUND_SUPPORTED) ||\
\r
2211 (defined PNG_READ_ALPHA_MODE_SUPPORTED)
\r
2212 /* Because PNG_COMPOSE does the gamma transform if there is something to
\r
2213 * do (if there is an alpha channel or transparency.)
\r
2215 !((png_ptr->transformations & PNG_COMPOSE) &&
\r
2216 ((png_ptr->num_trans != 0) ||
\r
2217 (png_ptr->color_type & PNG_COLOR_MASK_ALPHA))) &&
\r
2219 /* Because png_init_read_transformations transforms the palette, unless
\r
2220 * RGB_TO_GRAY will do the transform.
\r
2222 (png_ptr->color_type != PNG_COLOR_TYPE_PALETTE))
\r
2223 png_do_gamma(row_info, png_ptr->row_buf + 1, png_ptr);
\r
2226 #ifdef PNG_READ_STRIP_ALPHA_SUPPORTED
\r
2227 if ((png_ptr->transformations & PNG_STRIP_ALPHA) &&
\r
2228 (png_ptr->transformations & PNG_COMPOSE) &&
\r
2229 (row_info->color_type == PNG_COLOR_TYPE_RGB_ALPHA ||
\r
2230 row_info->color_type == PNG_COLOR_TYPE_GRAY_ALPHA))
\r
2231 png_do_strip_channel(row_info, png_ptr->row_buf + 1,
\r
2232 0 /* at_start == false, because SWAP_ALPHA happens later */);
\r
2235 #ifdef PNG_READ_ALPHA_MODE_SUPPORTED
\r
2236 if ((png_ptr->transformations & PNG_ENCODE_ALPHA) &&
\r
2237 (row_info->color_type & PNG_COLOR_MASK_ALPHA))
\r
2238 png_do_encode_alpha(row_info, png_ptr->row_buf + 1, png_ptr);
\r
2241 #ifdef PNG_READ_SCALE_16_TO_8_SUPPORTED
\r
2242 if (png_ptr->transformations & PNG_SCALE_16_TO_8)
\r
2243 png_do_scale_16_to_8(row_info, png_ptr->row_buf + 1);
\r
2246 #ifdef PNG_READ_STRIP_16_TO_8_SUPPORTED
\r
2247 /* There is no harm in doing both of these because only one has any effect,
\r
2248 * by putting the 'scale' option first if the app asks for scale (either by
\r
2249 * calling the API or in a TRANSFORM flag) this is what happens.
\r
2251 if (png_ptr->transformations & PNG_16_TO_8)
\r
2252 png_do_chop(row_info, png_ptr->row_buf + 1);
\r
2255 #ifdef PNG_READ_QUANTIZE_SUPPORTED
\r
2256 if (png_ptr->transformations & PNG_QUANTIZE)
\r
2258 png_do_quantize(row_info, png_ptr->row_buf + 1,
\r
2259 png_ptr->palette_lookup, png_ptr->quantize_index);
\r
2261 if (row_info->rowbytes == 0)
\r
2262 png_error(png_ptr, "png_do_quantize returned rowbytes=0");
\r
2264 #endif /* PNG_READ_QUANTIZE_SUPPORTED */
\r
2266 #ifdef PNG_READ_EXPAND_16_SUPPORTED
\r
2267 /* Do the expansion now, after all the arithmetic has been done. Notice
\r
2268 * that previous transformations can handle the PNG_EXPAND_16 flag if this
\r
2269 * is efficient (particularly true in the case of gamma correction, where
\r
2270 * better accuracy results faster!)
\r
2272 if (png_ptr->transformations & PNG_EXPAND_16)
\r
2273 png_do_expand_16(row_info, png_ptr->row_buf + 1);
\r
2276 #ifdef PNG_READ_GRAY_TO_RGB_SUPPORTED
\r
2277 /*NOTE: moved here in 1.5.4 (from much later in this list.) */
\r
2278 if ((png_ptr->transformations & PNG_GRAY_TO_RGB) &&
\r
2279 (png_ptr->mode & PNG_BACKGROUND_IS_GRAY))
\r
2280 png_do_gray_to_rgb(row_info, png_ptr->row_buf + 1);
\r
2283 #ifdef PNG_READ_INVERT_SUPPORTED
\r
2284 if (png_ptr->transformations & PNG_INVERT_MONO)
\r
2285 png_do_invert(row_info, png_ptr->row_buf + 1);
\r
2288 #ifdef PNG_READ_SHIFT_SUPPORTED
\r
2289 if (png_ptr->transformations & PNG_SHIFT)
\r
2290 png_do_unshift(row_info, png_ptr->row_buf + 1,
\r
2291 &(png_ptr->shift));
\r
2294 #ifdef PNG_READ_PACK_SUPPORTED
\r
2295 if (png_ptr->transformations & PNG_PACK)
\r
2296 png_do_unpack(row_info, png_ptr->row_buf + 1);
\r
2299 #ifdef PNG_READ_BGR_SUPPORTED
\r
2300 if (png_ptr->transformations & PNG_BGR)
\r
2301 png_do_bgr(row_info, png_ptr->row_buf + 1);
\r
2304 #ifdef PNG_READ_PACKSWAP_SUPPORTED
\r
2305 if (png_ptr->transformations & PNG_PACKSWAP)
\r
2306 png_do_packswap(row_info, png_ptr->row_buf + 1);
\r
2309 #ifdef PNG_READ_FILLER_SUPPORTED
\r
2310 if (png_ptr->transformations & PNG_FILLER)
\r
2311 png_do_read_filler(row_info, png_ptr->row_buf + 1,
\r
2312 (png_uint_32)png_ptr->filler, png_ptr->flags);
\r
2315 #ifdef PNG_READ_INVERT_ALPHA_SUPPORTED
\r
2316 if (png_ptr->transformations & PNG_INVERT_ALPHA)
\r
2317 png_do_read_invert_alpha(row_info, png_ptr->row_buf + 1);
\r
2320 #ifdef PNG_READ_SWAP_ALPHA_SUPPORTED
\r
2321 if (png_ptr->transformations & PNG_SWAP_ALPHA)
\r
2322 png_do_read_swap_alpha(row_info, png_ptr->row_buf + 1);
\r
2325 #ifdef PNG_READ_16BIT_SUPPORTED
\r
2326 #ifdef PNG_READ_SWAP_SUPPORTED
\r
2327 if (png_ptr->transformations & PNG_SWAP_BYTES)
\r
2328 png_do_swap(row_info, png_ptr->row_buf + 1);
\r
2332 #ifdef PNG_READ_USER_TRANSFORM_SUPPORTED
\r
2333 if (png_ptr->transformations & PNG_USER_TRANSFORM)
\r
2335 if (png_ptr->read_user_transform_fn != NULL)
\r
2336 (*(png_ptr->read_user_transform_fn)) /* User read transform function */
\r
2337 (png_ptr, /* png_ptr */
\r
2338 row_info, /* row_info: */
\r
2339 /* png_uint_32 width; width of row */
\r
2340 /* png_size_t rowbytes; number of bytes in row */
\r
2341 /* png_byte color_type; color type of pixels */
\r
2342 /* png_byte bit_depth; bit depth of samples */
\r
2343 /* png_byte channels; number of channels (1-4) */
\r
2344 /* png_byte pixel_depth; bits per pixel (depth*channels) */
\r
2345 png_ptr->row_buf + 1); /* start of pixel data for row */
\r
2346 #ifdef PNG_USER_TRANSFORM_PTR_SUPPORTED
\r
2347 if (png_ptr->user_transform_depth)
\r
2348 row_info->bit_depth = png_ptr->user_transform_depth;
\r
2350 if (png_ptr->user_transform_channels)
\r
2351 row_info->channels = png_ptr->user_transform_channels;
\r
2353 row_info->pixel_depth = (png_byte)(row_info->bit_depth *
\r
2354 row_info->channels);
\r
2356 row_info->rowbytes = PNG_ROWBYTES(row_info->pixel_depth, row_info->width);
\r
2361 #ifdef PNG_READ_PACK_SUPPORTED
\r
2362 /* Unpack pixels of 1, 2, or 4 bits per pixel into 1 byte per pixel,
\r
2363 * without changing the actual values. Thus, if you had a row with
\r
2364 * a bit depth of 1, you would end up with bytes that only contained
\r
2365 * the numbers 0 or 1. If you would rather they contain 0 and 255, use
\r
2366 * png_do_shift() after this.
\r
2368 void /* PRIVATE */
\r
2369 png_do_unpack(png_row_infop row_info, png_bytep row)
\r
2371 png_debug(1, "in png_do_unpack");
\r
2373 if (row_info->bit_depth < 8)
\r
2376 png_uint_32 row_width=row_info->width;
\r
2378 switch (row_info->bit_depth)
\r
2382 png_bytep sp = row + (png_size_t)((row_width - 1) >> 3);
\r
2383 png_bytep dp = row + (png_size_t)row_width - 1;
\r
2384 png_uint_32 shift = 7 - (int)((row_width + 7) & 0x07);
\r
2385 for (i = 0; i < row_width; i++)
\r
2387 *dp = (png_byte)((*sp >> shift) & 0x01);
\r
2406 png_bytep sp = row + (png_size_t)((row_width - 1) >> 2);
\r
2407 png_bytep dp = row + (png_size_t)row_width - 1;
\r
2408 png_uint_32 shift = (int)((3 - ((row_width + 3) & 0x03)) << 1);
\r
2409 for (i = 0; i < row_width; i++)
\r
2411 *dp = (png_byte)((*sp >> shift) & 0x03);
\r
2429 png_bytep sp = row + (png_size_t)((row_width - 1) >> 1);
\r
2430 png_bytep dp = row + (png_size_t)row_width - 1;
\r
2431 png_uint_32 shift = (int)((1 - ((row_width + 1) & 0x01)) << 2);
\r
2432 for (i = 0; i < row_width; i++)
\r
2434 *dp = (png_byte)((*sp >> shift) & 0x0f);
\r
2453 row_info->bit_depth = 8;
\r
2454 row_info->pixel_depth = (png_byte)(8 * row_info->channels);
\r
2455 row_info->rowbytes = row_width * row_info->channels;
\r
2460 #ifdef PNG_READ_SHIFT_SUPPORTED
\r
2461 /* Reverse the effects of png_do_shift. This routine merely shifts the
\r
2462 * pixels back to their significant bits values. Thus, if you have
\r
2463 * a row of bit depth 8, but only 5 are significant, this will shift
\r
2464 * the values back to 0 through 31.
\r
2466 void /* PRIVATE */
\r
2467 png_do_unshift(png_row_infop row_info, png_bytep row,
\r
2468 png_const_color_8p sig_bits)
\r
2472 png_debug(1, "in png_do_unshift");
\r
2474 /* The palette case has already been handled in the _init routine. */
\r
2475 color_type = row_info->color_type;
\r
2477 if (color_type != PNG_COLOR_TYPE_PALETTE)
\r
2481 int bit_depth = row_info->bit_depth;
\r
2483 if (color_type & PNG_COLOR_MASK_COLOR)
\r
2485 shift[channels++] = bit_depth - sig_bits->red;
\r
2486 shift[channels++] = bit_depth - sig_bits->green;
\r
2487 shift[channels++] = bit_depth - sig_bits->blue;
\r
2492 shift[channels++] = bit_depth - sig_bits->gray;
\r
2495 if (color_type & PNG_COLOR_MASK_ALPHA)
\r
2497 shift[channels++] = bit_depth - sig_bits->alpha;
\r
2501 int c, have_shift;
\r
2503 for (c = have_shift = 0; c < channels; ++c)
\r
2505 /* A shift of more than the bit depth is an error condition but it
\r
2506 * gets ignored here.
\r
2508 if (shift[c] <= 0 || shift[c] >= bit_depth)
\r
2519 switch (bit_depth)
\r
2522 /* Must be 1bpp gray: should not be here! */
\r
2527 /* Must be 2bpp gray */
\r
2528 /* assert(channels == 1 && shift[0] == 1) */
\r
2530 png_bytep bp = row;
\r
2531 png_bytep bp_end = bp + row_info->rowbytes;
\r
2533 while (bp < bp_end)
\r
2535 int b = (*bp >> 1) & 0x55;
\r
2536 *bp++ = (png_byte)b;
\r
2542 /* Must be 4bpp gray */
\r
2543 /* assert(channels == 1) */
\r
2545 png_bytep bp = row;
\r
2546 png_bytep bp_end = bp + row_info->rowbytes;
\r
2547 int gray_shift = shift[0];
\r
2548 int mask = 0xf >> gray_shift;
\r
2550 mask |= mask << 4;
\r
2552 while (bp < bp_end)
\r
2554 int b = (*bp >> gray_shift) & mask;
\r
2555 *bp++ = (png_byte)b;
\r
2561 /* Single byte components, G, GA, RGB, RGBA */
\r
2563 png_bytep bp = row;
\r
2564 png_bytep bp_end = bp + row_info->rowbytes;
\r
2567 while (bp < bp_end)
\r
2569 int b = *bp >> shift[channel];
\r
2570 if (++channel >= channels)
\r
2572 *bp++ = (png_byte)b;
\r
2577 #ifdef PNG_READ_16BIT_SUPPORTED
\r
2579 /* Double byte components, G, GA, RGB, RGBA */
\r
2581 png_bytep bp = row;
\r
2582 png_bytep bp_end = bp + row_info->rowbytes;
\r
2585 while (bp < bp_end)
\r
2587 int value = (bp[0] << 8) + bp[1];
\r
2589 value >>= shift[channel];
\r
2590 if (++channel >= channels)
\r
2592 *bp++ = (png_byte)(value >> 8);
\r
2593 *bp++ = (png_byte)(value & 0xff);
\r
2603 #ifdef PNG_READ_SCALE_16_TO_8_SUPPORTED
\r
2604 /* Scale rows of bit depth 16 down to 8 accurately */
\r
2605 void /* PRIVATE */
\r
2606 png_do_scale_16_to_8(png_row_infop row_info, png_bytep row)
\r
2608 png_debug(1, "in png_do_scale_16_to_8");
\r
2610 if (row_info->bit_depth == 16)
\r
2612 png_bytep sp = row; /* source */
\r
2613 png_bytep dp = row; /* destination */
\r
2614 png_bytep ep = sp + row_info->rowbytes; /* end+1 */
\r
2618 /* The input is an array of 16 bit components, these must be scaled to
\r
2619 * 8 bits each. For a 16 bit value V the required value (from the PNG
\r
2620 * specification) is:
\r
2622 * (V * 255) / 65535
\r
2624 * This reduces to round(V / 257), or floor((V + 128.5)/257)
\r
2626 * Represent V as the two byte value vhi.vlo. Make a guess that the
\r
2627 * result is the top byte of V, vhi, then the correction to this value
\r
2630 * error = floor(((V-vhi.vhi) + 128.5) / 257)
\r
2631 * = floor(((vlo-vhi) + 128.5) / 257)
\r
2633 * This can be approximated using integer arithmetic (and a signed
\r
2636 * error = (vlo-vhi+128) >> 8;
\r
2638 * The approximate differs from the exact answer only when (vlo-vhi) is
\r
2639 * 128; it then gives a correction of +1 when the exact correction is
\r
2640 * 0. This gives 128 errors. The exact answer (correct for all 16 bit
\r
2641 * input values) is:
\r
2643 * error = (vlo-vhi+128)*65535 >> 24;
\r
2645 * An alternative arithmetic calculation which also gives no errors is:
\r
2647 * (V * 255 + 32895) >> 16
\r
2650 png_int_32 tmp = *sp++; /* must be signed! */
\r
2651 tmp += (((int)*sp++ - tmp + 128) * 65535) >> 24;
\r
2652 *dp++ = (png_byte)tmp;
\r
2655 row_info->bit_depth = 8;
\r
2656 row_info->pixel_depth = (png_byte)(8 * row_info->channels);
\r
2657 row_info->rowbytes = row_info->width * row_info->channels;
\r
2662 #ifdef PNG_READ_STRIP_16_TO_8_SUPPORTED
\r
2663 void /* PRIVATE */
\r
2664 /* Simply discard the low byte. This was the default behavior prior
\r
2665 * to libpng-1.5.4.
\r
2667 png_do_chop(png_row_infop row_info, png_bytep row)
\r
2669 png_debug(1, "in png_do_chop");
\r
2671 if (row_info->bit_depth == 16)
\r
2673 png_bytep sp = row; /* source */
\r
2674 png_bytep dp = row; /* destination */
\r
2675 png_bytep ep = sp + row_info->rowbytes; /* end+1 */
\r
2680 sp += 2; /* skip low byte */
\r
2683 row_info->bit_depth = 8;
\r
2684 row_info->pixel_depth = (png_byte)(8 * row_info->channels);
\r
2685 row_info->rowbytes = row_info->width * row_info->channels;
\r
2690 #ifdef PNG_READ_SWAP_ALPHA_SUPPORTED
\r
2691 void /* PRIVATE */
\r
2692 png_do_read_swap_alpha(png_row_infop row_info, png_bytep row)
\r
2694 png_debug(1, "in png_do_read_swap_alpha");
\r
2697 png_uint_32 row_width = row_info->width;
\r
2698 if (row_info->color_type == PNG_COLOR_TYPE_RGB_ALPHA)
\r
2700 /* This converts from RGBA to ARGB */
\r
2701 if (row_info->bit_depth == 8)
\r
2703 png_bytep sp = row + row_info->rowbytes;
\r
2704 png_bytep dp = sp;
\r
2708 for (i = 0; i < row_width; i++)
\r
2711 *(--dp) = *(--sp);
\r
2712 *(--dp) = *(--sp);
\r
2713 *(--dp) = *(--sp);
\r
2718 #ifdef PNG_READ_16BIT_SUPPORTED
\r
2719 /* This converts from RRGGBBAA to AARRGGBB */
\r
2722 png_bytep sp = row + row_info->rowbytes;
\r
2723 png_bytep dp = sp;
\r
2727 for (i = 0; i < row_width; i++)
\r
2729 save[0] = *(--sp);
\r
2730 save[1] = *(--sp);
\r
2731 *(--dp) = *(--sp);
\r
2732 *(--dp) = *(--sp);
\r
2733 *(--dp) = *(--sp);
\r
2734 *(--dp) = *(--sp);
\r
2735 *(--dp) = *(--sp);
\r
2736 *(--dp) = *(--sp);
\r
2737 *(--dp) = save[0];
\r
2738 *(--dp) = save[1];
\r
2744 else if (row_info->color_type == PNG_COLOR_TYPE_GRAY_ALPHA)
\r
2746 /* This converts from GA to AG */
\r
2747 if (row_info->bit_depth == 8)
\r
2749 png_bytep sp = row + row_info->rowbytes;
\r
2750 png_bytep dp = sp;
\r
2754 for (i = 0; i < row_width; i++)
\r
2757 *(--dp) = *(--sp);
\r
2762 #ifdef PNG_READ_16BIT_SUPPORTED
\r
2763 /* This converts from GGAA to AAGG */
\r
2766 png_bytep sp = row + row_info->rowbytes;
\r
2767 png_bytep dp = sp;
\r
2771 for (i = 0; i < row_width; i++)
\r
2773 save[0] = *(--sp);
\r
2774 save[1] = *(--sp);
\r
2775 *(--dp) = *(--sp);
\r
2776 *(--dp) = *(--sp);
\r
2777 *(--dp) = save[0];
\r
2778 *(--dp) = save[1];
\r
2787 #ifdef PNG_READ_INVERT_ALPHA_SUPPORTED
\r
2788 void /* PRIVATE */
\r
2789 png_do_read_invert_alpha(png_row_infop row_info, png_bytep row)
\r
2791 png_uint_32 row_width;
\r
2792 png_debug(1, "in png_do_read_invert_alpha");
\r
2794 row_width = row_info->width;
\r
2795 if (row_info->color_type == PNG_COLOR_TYPE_RGB_ALPHA)
\r
2797 if (row_info->bit_depth == 8)
\r
2799 /* This inverts the alpha channel in RGBA */
\r
2800 png_bytep sp = row + row_info->rowbytes;
\r
2801 png_bytep dp = sp;
\r
2804 for (i = 0; i < row_width; i++)
\r
2806 *(--dp) = (png_byte)(255 - *(--sp));
\r
2808 /* This does nothing:
\r
2809 *(--dp) = *(--sp);
\r
2810 *(--dp) = *(--sp);
\r
2811 *(--dp) = *(--sp);
\r
2812 We can replace it with:
\r
2819 #ifdef PNG_READ_16BIT_SUPPORTED
\r
2820 /* This inverts the alpha channel in RRGGBBAA */
\r
2823 png_bytep sp = row + row_info->rowbytes;
\r
2824 png_bytep dp = sp;
\r
2827 for (i = 0; i < row_width; i++)
\r
2829 *(--dp) = (png_byte)(255 - *(--sp));
\r
2830 *(--dp) = (png_byte)(255 - *(--sp));
\r
2832 /* This does nothing:
\r
2833 *(--dp) = *(--sp);
\r
2834 *(--dp) = *(--sp);
\r
2835 *(--dp) = *(--sp);
\r
2836 *(--dp) = *(--sp);
\r
2837 *(--dp) = *(--sp);
\r
2838 *(--dp) = *(--sp);
\r
2839 We can replace it with:
\r
2847 else if (row_info->color_type == PNG_COLOR_TYPE_GRAY_ALPHA)
\r
2849 if (row_info->bit_depth == 8)
\r
2851 /* This inverts the alpha channel in GA */
\r
2852 png_bytep sp = row + row_info->rowbytes;
\r
2853 png_bytep dp = sp;
\r
2856 for (i = 0; i < row_width; i++)
\r
2858 *(--dp) = (png_byte)(255 - *(--sp));
\r
2859 *(--dp) = *(--sp);
\r
2863 #ifdef PNG_READ_16BIT_SUPPORTED
\r
2866 /* This inverts the alpha channel in GGAA */
\r
2867 png_bytep sp = row + row_info->rowbytes;
\r
2868 png_bytep dp = sp;
\r
2871 for (i = 0; i < row_width; i++)
\r
2873 *(--dp) = (png_byte)(255 - *(--sp));
\r
2874 *(--dp) = (png_byte)(255 - *(--sp));
\r
2876 *(--dp) = *(--sp);
\r
2877 *(--dp) = *(--sp);
\r
2888 #ifdef PNG_READ_FILLER_SUPPORTED
\r
2889 /* Add filler channel if we have RGB color */
\r
2890 void /* PRIVATE */
\r
2891 png_do_read_filler(png_row_infop row_info, png_bytep row,
\r
2892 png_uint_32 filler, png_uint_32 flags)
\r
2895 png_uint_32 row_width = row_info->width;
\r
2897 #ifdef PNG_READ_16BIT_SUPPORTED
\r
2898 png_byte hi_filler = (png_byte)((filler>>8) & 0xff);
\r
2900 png_byte lo_filler = (png_byte)(filler & 0xff);
\r
2902 png_debug(1, "in png_do_read_filler");
\r
2905 row_info->color_type == PNG_COLOR_TYPE_GRAY)
\r
2907 if (row_info->bit_depth == 8)
\r
2909 if (flags & PNG_FLAG_FILLER_AFTER)
\r
2911 /* This changes the data from G to GX */
\r
2912 png_bytep sp = row + (png_size_t)row_width;
\r
2913 png_bytep dp = sp + (png_size_t)row_width;
\r
2914 for (i = 1; i < row_width; i++)
\r
2916 *(--dp) = lo_filler;
\r
2917 *(--dp) = *(--sp);
\r
2919 *(--dp) = lo_filler;
\r
2920 row_info->channels = 2;
\r
2921 row_info->pixel_depth = 16;
\r
2922 row_info->rowbytes = row_width * 2;
\r
2927 /* This changes the data from G to XG */
\r
2928 png_bytep sp = row + (png_size_t)row_width;
\r
2929 png_bytep dp = sp + (png_size_t)row_width;
\r
2930 for (i = 0; i < row_width; i++)
\r
2932 *(--dp) = *(--sp);
\r
2933 *(--dp) = lo_filler;
\r
2935 row_info->channels = 2;
\r
2936 row_info->pixel_depth = 16;
\r
2937 row_info->rowbytes = row_width * 2;
\r
2941 #ifdef PNG_READ_16BIT_SUPPORTED
\r
2942 else if (row_info->bit_depth == 16)
\r
2944 if (flags & PNG_FLAG_FILLER_AFTER)
\r
2946 /* This changes the data from GG to GGXX */
\r
2947 png_bytep sp = row + (png_size_t)row_width * 2;
\r
2948 png_bytep dp = sp + (png_size_t)row_width * 2;
\r
2949 for (i = 1; i < row_width; i++)
\r
2951 *(--dp) = hi_filler;
\r
2952 *(--dp) = lo_filler;
\r
2953 *(--dp) = *(--sp);
\r
2954 *(--dp) = *(--sp);
\r
2956 *(--dp) = hi_filler;
\r
2957 *(--dp) = lo_filler;
\r
2958 row_info->channels = 2;
\r
2959 row_info->pixel_depth = 32;
\r
2960 row_info->rowbytes = row_width * 4;
\r
2965 /* This changes the data from GG to XXGG */
\r
2966 png_bytep sp = row + (png_size_t)row_width * 2;
\r
2967 png_bytep dp = sp + (png_size_t)row_width * 2;
\r
2968 for (i = 0; i < row_width; i++)
\r
2970 *(--dp) = *(--sp);
\r
2971 *(--dp) = *(--sp);
\r
2972 *(--dp) = hi_filler;
\r
2973 *(--dp) = lo_filler;
\r
2975 row_info->channels = 2;
\r
2976 row_info->pixel_depth = 32;
\r
2977 row_info->rowbytes = row_width * 4;
\r
2981 } /* COLOR_TYPE == GRAY */
\r
2982 else if (row_info->color_type == PNG_COLOR_TYPE_RGB)
\r
2984 if (row_info->bit_depth == 8)
\r
2986 if (flags & PNG_FLAG_FILLER_AFTER)
\r
2988 /* This changes the data from RGB to RGBX */
\r
2989 png_bytep sp = row + (png_size_t)row_width * 3;
\r
2990 png_bytep dp = sp + (png_size_t)row_width;
\r
2991 for (i = 1; i < row_width; i++)
\r
2993 *(--dp) = lo_filler;
\r
2994 *(--dp) = *(--sp);
\r
2995 *(--dp) = *(--sp);
\r
2996 *(--dp) = *(--sp);
\r
2998 *(--dp) = lo_filler;
\r
2999 row_info->channels = 4;
\r
3000 row_info->pixel_depth = 32;
\r
3001 row_info->rowbytes = row_width * 4;
\r
3006 /* This changes the data from RGB to XRGB */
\r
3007 png_bytep sp = row + (png_size_t)row_width * 3;
\r
3008 png_bytep dp = sp + (png_size_t)row_width;
\r
3009 for (i = 0; i < row_width; i++)
\r
3011 *(--dp) = *(--sp);
\r
3012 *(--dp) = *(--sp);
\r
3013 *(--dp) = *(--sp);
\r
3014 *(--dp) = lo_filler;
\r
3016 row_info->channels = 4;
\r
3017 row_info->pixel_depth = 32;
\r
3018 row_info->rowbytes = row_width * 4;
\r
3022 #ifdef PNG_READ_16BIT_SUPPORTED
\r
3023 else if (row_info->bit_depth == 16)
\r
3025 if (flags & PNG_FLAG_FILLER_AFTER)
\r
3027 /* This changes the data from RRGGBB to RRGGBBXX */
\r
3028 png_bytep sp = row + (png_size_t)row_width * 6;
\r
3029 png_bytep dp = sp + (png_size_t)row_width * 2;
\r
3030 for (i = 1; i < row_width; i++)
\r
3032 *(--dp) = hi_filler;
\r
3033 *(--dp) = lo_filler;
\r
3034 *(--dp) = *(--sp);
\r
3035 *(--dp) = *(--sp);
\r
3036 *(--dp) = *(--sp);
\r
3037 *(--dp) = *(--sp);
\r
3038 *(--dp) = *(--sp);
\r
3039 *(--dp) = *(--sp);
\r
3041 *(--dp) = hi_filler;
\r
3042 *(--dp) = lo_filler;
\r
3043 row_info->channels = 4;
\r
3044 row_info->pixel_depth = 64;
\r
3045 row_info->rowbytes = row_width * 8;
\r
3050 /* This changes the data from RRGGBB to XXRRGGBB */
\r
3051 png_bytep sp = row + (png_size_t)row_width * 6;
\r
3052 png_bytep dp = sp + (png_size_t)row_width * 2;
\r
3053 for (i = 0; i < row_width; i++)
\r
3055 *(--dp) = *(--sp);
\r
3056 *(--dp) = *(--sp);
\r
3057 *(--dp) = *(--sp);
\r
3058 *(--dp) = *(--sp);
\r
3059 *(--dp) = *(--sp);
\r
3060 *(--dp) = *(--sp);
\r
3061 *(--dp) = hi_filler;
\r
3062 *(--dp) = lo_filler;
\r
3065 row_info->channels = 4;
\r
3066 row_info->pixel_depth = 64;
\r
3067 row_info->rowbytes = row_width * 8;
\r
3071 } /* COLOR_TYPE == RGB */
\r
3075 #ifdef PNG_READ_GRAY_TO_RGB_SUPPORTED
\r
3076 /* Expand grayscale files to RGB, with or without alpha */
\r
3077 void /* PRIVATE */
\r
3078 png_do_gray_to_rgb(png_row_infop row_info, png_bytep row)
\r
3081 png_uint_32 row_width = row_info->width;
\r
3083 png_debug(1, "in png_do_gray_to_rgb");
\r
3085 if (row_info->bit_depth >= 8 &&
\r
3086 !(row_info->color_type & PNG_COLOR_MASK_COLOR))
\r
3088 if (row_info->color_type == PNG_COLOR_TYPE_GRAY)
\r
3090 if (row_info->bit_depth == 8)
\r
3092 /* This changes G to RGB */
\r
3093 png_bytep sp = row + (png_size_t)row_width - 1;
\r
3094 png_bytep dp = sp + (png_size_t)row_width * 2;
\r
3095 for (i = 0; i < row_width; i++)
\r
3099 *(dp--) = *(sp--);
\r
3105 /* This changes GG to RRGGBB */
\r
3106 png_bytep sp = row + (png_size_t)row_width * 2 - 1;
\r
3107 png_bytep dp = sp + (png_size_t)row_width * 4;
\r
3108 for (i = 0; i < row_width; i++)
\r
3111 *(dp--) = *(sp - 1);
\r
3113 *(dp--) = *(sp - 1);
\r
3114 *(dp--) = *(sp--);
\r
3115 *(dp--) = *(sp--);
\r
3120 else if (row_info->color_type == PNG_COLOR_TYPE_GRAY_ALPHA)
\r
3122 if (row_info->bit_depth == 8)
\r
3124 /* This changes GA to RGBA */
\r
3125 png_bytep sp = row + (png_size_t)row_width * 2 - 1;
\r
3126 png_bytep dp = sp + (png_size_t)row_width * 2;
\r
3127 for (i = 0; i < row_width; i++)
\r
3129 *(dp--) = *(sp--);
\r
3132 *(dp--) = *(sp--);
\r
3138 /* This changes GGAA to RRGGBBAA */
\r
3139 png_bytep sp = row + (png_size_t)row_width * 4 - 1;
\r
3140 png_bytep dp = sp + (png_size_t)row_width * 4;
\r
3141 for (i = 0; i < row_width; i++)
\r
3143 *(dp--) = *(sp--);
\r
3144 *(dp--) = *(sp--);
\r
3146 *(dp--) = *(sp - 1);
\r
3148 *(dp--) = *(sp - 1);
\r
3149 *(dp--) = *(sp--);
\r
3150 *(dp--) = *(sp--);
\r
3154 row_info->channels = (png_byte)(row_info->channels + 2);
\r
3155 row_info->color_type |= PNG_COLOR_MASK_COLOR;
\r
3156 row_info->pixel_depth = (png_byte)(row_info->channels *
\r
3157 row_info->bit_depth);
\r
3158 row_info->rowbytes = PNG_ROWBYTES(row_info->pixel_depth, row_width);
\r
3163 #ifdef PNG_READ_RGB_TO_GRAY_SUPPORTED
\r
3164 /* Reduce RGB files to grayscale, with or without alpha
\r
3165 * using the equation given in Poynton's ColorFAQ of 1998-01-04 at
\r
3166 * <http://www.inforamp.net/~poynton/> (THIS LINK IS DEAD June 2008 but
\r
3167 * versions dated 1998 through November 2002 have been archived at
\r
3168 * http://web.archive.org/web/20000816232553/http://www.inforamp.net/
\r
3169 * ~poynton/notes/colour_and_gamma/ColorFAQ.txt )
\r
3170 * Charles Poynton poynton at poynton.com
\r
3172 * Y = 0.212671 * R + 0.715160 * G + 0.072169 * B
\r
3174 * which can be expressed with integers as
\r
3176 * Y = (6969 * R + 23434 * G + 2365 * B)/32768
\r
3178 * Poynton's current link (as of January 2003 through July 2011):
\r
3179 * <http://www.poynton.com/notes/colour_and_gamma/>
\r
3180 * has changed the numbers slightly:
\r
3182 * Y = 0.2126*R + 0.7152*G + 0.0722*B
\r
3184 * which can be expressed with integers as
\r
3186 * Y = (6966 * R + 23436 * G + 2366 * B)/32768
\r
3188 * Historically, however, libpng uses numbers derived from the ITU-R Rec 709
\r
3189 * end point chromaticities and the D65 white point. Depending on the
\r
3190 * precision used for the D65 white point this produces a variety of different
\r
3191 * numbers, however if the four decimal place value used in ITU-R Rec 709 is
\r
3192 * used (0.3127,0.3290) the Y calculation would be:
\r
3194 * Y = (6968 * R + 23435 * G + 2366 * B)/32768
\r
3196 * While this is correct the rounding results in an overflow for white, because
\r
3197 * the sum of the rounded coefficients is 32769, not 32768. Consequently
\r
3198 * libpng uses, instead, the closest non-overflowing approximation:
\r
3200 * Y = (6968 * R + 23434 * G + 2366 * B)/32768
\r
3202 * Starting with libpng-1.5.5, if the image being converted has a cHRM chunk
\r
3203 * (including an sRGB chunk) then the chromaticities are used to calculate the
\r
3204 * coefficients. See the chunk handling in pngrutil.c for more information.
\r
3206 * In all cases the calculation is to be done in a linear colorspace. If no
\r
3207 * gamma information is available to correct the encoding of the original RGB
\r
3208 * values this results in an implicit assumption that the original PNG RGB
\r
3209 * values were linear.
\r
3211 * Other integer coefficents can be used via png_set_rgb_to_gray(). Because
\r
3212 * the API takes just red and green coefficients the blue coefficient is
\r
3213 * calculated to make the sum 32768. This will result in different rounding
\r
3214 * to that used above.
\r
3217 png_do_rgb_to_gray(png_structp png_ptr, png_row_infop row_info, png_bytep row)
\r
3220 int rgb_error = 0;
\r
3222 png_debug(1, "in png_do_rgb_to_gray");
\r
3224 if (!(row_info->color_type & PNG_COLOR_MASK_PALETTE) &&
\r
3225 (row_info->color_type & PNG_COLOR_MASK_COLOR))
\r
3227 PNG_CONST png_uint_32 rc = png_ptr->rgb_to_gray_red_coeff;
\r
3228 PNG_CONST png_uint_32 gc = png_ptr->rgb_to_gray_green_coeff;
\r
3229 PNG_CONST png_uint_32 bc = 32768 - rc - gc;
\r
3230 PNG_CONST png_uint_32 row_width = row_info->width;
\r
3231 PNG_CONST int have_alpha =
\r
3232 (row_info->color_type & PNG_COLOR_MASK_ALPHA) != 0;
\r
3234 if (row_info->bit_depth == 8)
\r
3236 #if defined(PNG_READ_GAMMA_SUPPORTED) || defined(PNG_READ_BACKGROUND_SUPPORTED)
\r
3237 /* Notice that gamma to/from 1 are not necessarily inverses (if
\r
3238 * there is an overall gamma correction). Prior to 1.5.5 this code
\r
3239 * checked the linearized values for equality; this doesn't match
\r
3240 * the documentation, the original values must be checked.
\r
3242 if (png_ptr->gamma_from_1 != NULL && png_ptr->gamma_to_1 != NULL)
\r
3244 png_bytep sp = row;
\r
3245 png_bytep dp = row;
\r
3248 for (i = 0; i < row_width; i++)
\r
3250 png_byte red = *(sp++);
\r
3251 png_byte green = *(sp++);
\r
3252 png_byte blue = *(sp++);
\r
3254 if (red != green || red != blue)
\r
3256 red = png_ptr->gamma_to_1[red];
\r
3257 green = png_ptr->gamma_to_1[green];
\r
3258 blue = png_ptr->gamma_to_1[blue];
\r
3261 *(dp++) = png_ptr->gamma_from_1[
\r
3262 (rc*red + gc*green + bc*blue + 16384)>>15];
\r
3267 /* If there is no overall correction the table will not be
\r
3270 if (png_ptr->gamma_table != NULL)
\r
3271 red = png_ptr->gamma_table[red];
\r
3277 *(dp++) = *(sp++);
\r
3283 png_bytep sp = row;
\r
3284 png_bytep dp = row;
\r
3287 for (i = 0; i < row_width; i++)
\r
3289 png_byte red = *(sp++);
\r
3290 png_byte green = *(sp++);
\r
3291 png_byte blue = *(sp++);
\r
3293 if (red != green || red != blue)
\r
3296 /*NOTE: this is the historical approach which simply
\r
3297 * truncates the results.
\r
3299 *(dp++) = (png_byte)((rc*red + gc*green + bc*blue)>>15);
\r
3306 *(dp++) = *(sp++);
\r
3311 else /* RGB bit_depth == 16 */
\r
3313 #if defined(PNG_READ_GAMMA_SUPPORTED) || defined(PNG_READ_BACKGROUND_SUPPORTED)
\r
3314 if (png_ptr->gamma_16_to_1 != NULL && png_ptr->gamma_16_from_1 != NULL)
\r
3316 png_bytep sp = row;
\r
3317 png_bytep dp = row;
\r
3320 for (i = 0; i < row_width; i++)
\r
3322 png_uint_16 red, green, blue, w;
\r
3324 red = (png_uint_16)(((*(sp))<<8) | *(sp + 1)); sp += 2;
\r
3325 green = (png_uint_16)(((*(sp))<<8) | *(sp + 1)); sp += 2;
\r
3326 blue = (png_uint_16)(((*(sp))<<8) | *(sp + 1)); sp += 2;
\r
3328 if (red == green && red == blue)
\r
3330 if (png_ptr->gamma_16_table != NULL)
\r
3331 w = png_ptr->gamma_16_table[(red&0xff)
\r
3332 >> png_ptr->gamma_shift][red>>8];
\r
3340 png_uint_16 red_1 = png_ptr->gamma_16_to_1[(red&0xff)
\r
3341 >> png_ptr->gamma_shift][red>>8];
\r
3342 png_uint_16 green_1 =
\r
3343 png_ptr->gamma_16_to_1[(green&0xff) >>
\r
3344 png_ptr->gamma_shift][green>>8];
\r
3345 png_uint_16 blue_1 = png_ptr->gamma_16_to_1[(blue&0xff)
\r
3346 >> png_ptr->gamma_shift][blue>>8];
\r
3347 png_uint_16 gray16 = (png_uint_16)((rc*red_1 + gc*green_1
\r
3348 + bc*blue_1 + 16384)>>15);
\r
3349 w = png_ptr->gamma_16_from_1[(gray16&0xff) >>
\r
3350 png_ptr->gamma_shift][gray16 >> 8];
\r
3354 *(dp++) = (png_byte)((w>>8) & 0xff);
\r
3355 *(dp++) = (png_byte)(w & 0xff);
\r
3359 *(dp++) = *(sp++);
\r
3360 *(dp++) = *(sp++);
\r
3367 png_bytep sp = row;
\r
3368 png_bytep dp = row;
\r
3371 for (i = 0; i < row_width; i++)
\r
3373 png_uint_16 red, green, blue, gray16;
\r
3375 red = (png_uint_16)(((*(sp))<<8) | *(sp + 1)); sp += 2;
\r
3376 green = (png_uint_16)(((*(sp))<<8) | *(sp + 1)); sp += 2;
\r
3377 blue = (png_uint_16)(((*(sp))<<8) | *(sp + 1)); sp += 2;
\r
3379 if (red != green || red != blue)
\r
3382 /* From 1.5.5 in the 16 bit case do the accurate conversion even
\r
3383 * in the 'fast' case - this is because this is where the code
\r
3384 * ends up when handling linear 16 bit data.
\r
3386 gray16 = (png_uint_16)((rc*red + gc*green + bc*blue + 16384) >>
\r
3388 *(dp++) = (png_byte)((gray16>>8) & 0xff);
\r
3389 *(dp++) = (png_byte)(gray16 & 0xff);
\r
3393 *(dp++) = *(sp++);
\r
3394 *(dp++) = *(sp++);
\r
3400 row_info->channels = (png_byte)(row_info->channels - 2);
\r
3401 row_info->color_type = (png_byte)(row_info->color_type &
\r
3402 ~PNG_COLOR_MASK_COLOR);
\r
3403 row_info->pixel_depth = (png_byte)(row_info->channels *
\r
3404 row_info->bit_depth);
\r
3405 row_info->rowbytes = PNG_ROWBYTES(row_info->pixel_depth, row_width);
\r
3410 #endif /* PNG_READ_TRANSFORMS_SUPPORTED */
\r
3412 #ifdef PNG_BUILD_GRAYSCALE_PALETTE_SUPPORTED
\r
3413 /* Build a grayscale palette. Palette is assumed to be 1 << bit_depth
\r
3414 * large of png_color. This lets grayscale images be treated as
\r
3415 * paletted. Most useful for gamma correction and simplification
\r
3416 * of code. This API is not used internally.
\r
3419 png_build_grayscale_palette(int bit_depth, png_colorp palette)
\r
3426 png_debug(1, "in png_do_build_grayscale_palette");
\r
3428 if (palette == NULL)
\r
3431 switch (bit_depth)
\r
3449 num_palette = 256;
\r
3459 for (i = 0, v = 0; i < num_palette; i++, v += color_inc)
\r
3461 palette[i].red = (png_byte)v;
\r
3462 palette[i].green = (png_byte)v;
\r
3463 palette[i].blue = (png_byte)v;
\r
3469 #ifdef PNG_READ_TRANSFORMS_SUPPORTED
\r
3470 #if (defined PNG_READ_BACKGROUND_SUPPORTED) ||\
\r
3471 (defined PNG_READ_ALPHA_MODE_SUPPORTED)
\r
3472 /* Replace any alpha or transparency with the supplied background color.
\r
3473 * "background" is already in the screen gamma, while "background_1" is
\r
3474 * at a gamma of 1.0. Paletted files have already been taken care of.
\r
3476 void /* PRIVATE */
\r
3477 png_do_compose(png_row_infop row_info, png_bytep row, png_structp png_ptr)
\r
3479 #ifdef PNG_READ_GAMMA_SUPPORTED
\r
3480 png_const_bytep gamma_table = png_ptr->gamma_table;
\r
3481 png_const_bytep gamma_from_1 = png_ptr->gamma_from_1;
\r
3482 png_const_bytep gamma_to_1 = png_ptr->gamma_to_1;
\r
3483 png_const_uint_16pp gamma_16 = png_ptr->gamma_16_table;
\r
3484 png_const_uint_16pp gamma_16_from_1 = png_ptr->gamma_16_from_1;
\r
3485 png_const_uint_16pp gamma_16_to_1 = png_ptr->gamma_16_to_1;
\r
3486 int gamma_shift = png_ptr->gamma_shift;
\r
3491 png_uint_32 row_width = row_info->width;
\r
3492 int optimize = (png_ptr->flags & PNG_FLAG_OPTIMIZE_ALPHA) != 0;
\r
3495 png_debug(1, "in png_do_compose");
\r
3498 switch (row_info->color_type)
\r
3500 case PNG_COLOR_TYPE_GRAY:
\r
3502 switch (row_info->bit_depth)
\r
3508 for (i = 0; i < row_width; i++)
\r
3510 if ((png_uint_16)((*sp >> shift) & 0x01)
\r
3511 == png_ptr->trans_color.gray)
\r
3513 *sp &= (png_byte)((0x7f7f >> (7 - shift)) & 0xff);
\r
3514 *sp |= (png_byte)(png_ptr->background.gray << shift);
\r
3531 #ifdef PNG_READ_GAMMA_SUPPORTED
\r
3532 if (gamma_table != NULL)
\r
3536 for (i = 0; i < row_width; i++)
\r
3538 if ((png_uint_16)((*sp >> shift) & 0x03)
\r
3539 == png_ptr->trans_color.gray)
\r
3541 *sp &= (png_byte)((0x3f3f >> (6 - shift)) & 0xff);
\r
3542 *sp |= (png_byte)(png_ptr->background.gray << shift);
\r
3547 png_byte p = (png_byte)((*sp >> shift) & 0x03);
\r
3548 png_byte g = (png_byte)((gamma_table [p | (p << 2) |
\r
3549 (p << 4) | (p << 6)] >> 6) & 0x03);
\r
3550 *sp &= (png_byte)((0x3f3f >> (6 - shift)) & 0xff);
\r
3551 *sp |= (png_byte)(g << shift);
\r
3570 for (i = 0; i < row_width; i++)
\r
3572 if ((png_uint_16)((*sp >> shift) & 0x03)
\r
3573 == png_ptr->trans_color.gray)
\r
3575 *sp &= (png_byte)((0x3f3f >> (6 - shift)) & 0xff);
\r
3576 *sp |= (png_byte)(png_ptr->background.gray << shift);
\r
3594 #ifdef PNG_READ_GAMMA_SUPPORTED
\r
3595 if (gamma_table != NULL)
\r
3599 for (i = 0; i < row_width; i++)
\r
3601 if ((png_uint_16)((*sp >> shift) & 0x0f)
\r
3602 == png_ptr->trans_color.gray)
\r
3604 *sp &= (png_byte)((0xf0f >> (4 - shift)) & 0xff);
\r
3605 *sp |= (png_byte)(png_ptr->background.gray << shift);
\r
3610 png_byte p = (png_byte)((*sp >> shift) & 0x0f);
\r
3611 png_byte g = (png_byte)((gamma_table[p |
\r
3612 (p << 4)] >> 4) & 0x0f);
\r
3613 *sp &= (png_byte)((0xf0f >> (4 - shift)) & 0xff);
\r
3614 *sp |= (png_byte)(g << shift);
\r
3633 for (i = 0; i < row_width; i++)
\r
3635 if ((png_uint_16)((*sp >> shift) & 0x0f)
\r
3636 == png_ptr->trans_color.gray)
\r
3638 *sp &= (png_byte)((0xf0f >> (4 - shift)) & 0xff);
\r
3639 *sp |= (png_byte)(png_ptr->background.gray << shift);
\r
3657 #ifdef PNG_READ_GAMMA_SUPPORTED
\r
3658 if (gamma_table != NULL)
\r
3661 for (i = 0; i < row_width; i++, sp++)
\r
3663 if (*sp == png_ptr->trans_color.gray)
\r
3664 *sp = (png_byte)png_ptr->background.gray;
\r
3667 *sp = gamma_table[*sp];
\r
3674 for (i = 0; i < row_width; i++, sp++)
\r
3676 if (*sp == png_ptr->trans_color.gray)
\r
3677 *sp = (png_byte)png_ptr->background.gray;
\r
3685 #ifdef PNG_READ_GAMMA_SUPPORTED
\r
3686 if (gamma_16 != NULL)
\r
3689 for (i = 0; i < row_width; i++, sp += 2)
\r
3693 v = (png_uint_16)(((*sp) << 8) + *(sp + 1));
\r
3695 if (v == png_ptr->trans_color.gray)
\r
3697 /* Background is already in screen gamma */
\r
3698 *sp = (png_byte)((png_ptr->background.gray >> 8) & 0xff);
\r
3699 *(sp + 1) = (png_byte)(png_ptr->background.gray & 0xff);
\r
3704 v = gamma_16[*(sp + 1) >> gamma_shift][*sp];
\r
3705 *sp = (png_byte)((v >> 8) & 0xff);
\r
3706 *(sp + 1) = (png_byte)(v & 0xff);
\r
3714 for (i = 0; i < row_width; i++, sp += 2)
\r
3718 v = (png_uint_16)(((*sp) << 8) + *(sp + 1));
\r
3720 if (v == png_ptr->trans_color.gray)
\r
3722 *sp = (png_byte)((png_ptr->background.gray >> 8) & 0xff);
\r
3723 *(sp + 1) = (png_byte)(png_ptr->background.gray & 0xff);
\r
3736 case PNG_COLOR_TYPE_RGB:
\r
3738 if (row_info->bit_depth == 8)
\r
3740 #ifdef PNG_READ_GAMMA_SUPPORTED
\r
3741 if (gamma_table != NULL)
\r
3744 for (i = 0; i < row_width; i++, sp += 3)
\r
3746 if (*sp == png_ptr->trans_color.red &&
\r
3747 *(sp + 1) == png_ptr->trans_color.green &&
\r
3748 *(sp + 2) == png_ptr->trans_color.blue)
\r
3750 *sp = (png_byte)png_ptr->background.red;
\r
3751 *(sp + 1) = (png_byte)png_ptr->background.green;
\r
3752 *(sp + 2) = (png_byte)png_ptr->background.blue;
\r
3757 *sp = gamma_table[*sp];
\r
3758 *(sp + 1) = gamma_table[*(sp + 1)];
\r
3759 *(sp + 2) = gamma_table[*(sp + 2)];
\r
3767 for (i = 0; i < row_width; i++, sp += 3)
\r
3769 if (*sp == png_ptr->trans_color.red &&
\r
3770 *(sp + 1) == png_ptr->trans_color.green &&
\r
3771 *(sp + 2) == png_ptr->trans_color.blue)
\r
3773 *sp = (png_byte)png_ptr->background.red;
\r
3774 *(sp + 1) = (png_byte)png_ptr->background.green;
\r
3775 *(sp + 2) = (png_byte)png_ptr->background.blue;
\r
3780 else /* if (row_info->bit_depth == 16) */
\r
3782 #ifdef PNG_READ_GAMMA_SUPPORTED
\r
3783 if (gamma_16 != NULL)
\r
3786 for (i = 0; i < row_width; i++, sp += 6)
\r
3788 png_uint_16 r = (png_uint_16)(((*sp) << 8) + *(sp + 1));
\r
3790 png_uint_16 g = (png_uint_16)(((*(sp + 2)) << 8)
\r
3793 png_uint_16 b = (png_uint_16)(((*(sp + 4)) << 8)
\r
3796 if (r == png_ptr->trans_color.red &&
\r
3797 g == png_ptr->trans_color.green &&
\r
3798 b == png_ptr->trans_color.blue)
\r
3800 /* Background is already in screen gamma */
\r
3801 *sp = (png_byte)((png_ptr->background.red >> 8) & 0xff);
\r
3802 *(sp + 1) = (png_byte)(png_ptr->background.red & 0xff);
\r
3803 *(sp + 2) = (png_byte)((png_ptr->background.green >> 8) & 0xff);
\r
3804 *(sp + 3) = (png_byte)(png_ptr->background.green & 0xff);
\r
3805 *(sp + 4) = (png_byte)((png_ptr->background.blue >> 8) & 0xff);
\r
3806 *(sp + 5) = (png_byte)(png_ptr->background.blue & 0xff);
\r
3811 png_uint_16 v = gamma_16[*(sp + 1) >> gamma_shift][*sp];
\r
3812 *sp = (png_byte)((v >> 8) & 0xff);
\r
3813 *(sp + 1) = (png_byte)(v & 0xff);
\r
3815 v = gamma_16[*(sp + 3) >> gamma_shift][*(sp + 2)];
\r
3816 *(sp + 2) = (png_byte)((v >> 8) & 0xff);
\r
3817 *(sp + 3) = (png_byte)(v & 0xff);
\r
3819 v = gamma_16[*(sp + 5) >> gamma_shift][*(sp + 4)];
\r
3820 *(sp + 4) = (png_byte)((v >> 8) & 0xff);
\r
3821 *(sp + 5) = (png_byte)(v & 0xff);
\r
3830 for (i = 0; i < row_width; i++, sp += 6)
\r
3832 png_uint_16 r = (png_uint_16)(((*sp) << 8) + *(sp + 1));
\r
3834 png_uint_16 g = (png_uint_16)(((*(sp + 2)) << 8)
\r
3837 png_uint_16 b = (png_uint_16)(((*(sp + 4)) << 8)
\r
3840 if (r == png_ptr->trans_color.red &&
\r
3841 g == png_ptr->trans_color.green &&
\r
3842 b == png_ptr->trans_color.blue)
\r
3844 *sp = (png_byte)((png_ptr->background.red >> 8) & 0xff);
\r
3845 *(sp + 1) = (png_byte)(png_ptr->background.red & 0xff);
\r
3846 *(sp + 2) = (png_byte)((png_ptr->background.green >> 8) & 0xff);
\r
3847 *(sp + 3) = (png_byte)(png_ptr->background.green & 0xff);
\r
3848 *(sp + 4) = (png_byte)((png_ptr->background.blue >> 8) & 0xff);
\r
3849 *(sp + 5) = (png_byte)(png_ptr->background.blue & 0xff);
\r
3857 case PNG_COLOR_TYPE_GRAY_ALPHA:
\r
3859 if (row_info->bit_depth == 8)
\r
3861 #ifdef PNG_READ_GAMMA_SUPPORTED
\r
3862 if (gamma_to_1 != NULL && gamma_from_1 != NULL &&
\r
3863 gamma_table != NULL)
\r
3866 for (i = 0; i < row_width; i++, sp += 2)
\r
3868 png_uint_16 a = *(sp + 1);
\r
3871 *sp = gamma_table[*sp];
\r
3875 /* Background is already in screen gamma */
\r
3876 *sp = (png_byte)png_ptr->background.gray;
\r
3883 v = gamma_to_1[*sp];
\r
3884 png_composite(w, v, a, png_ptr->background_1.gray);
\r
3886 w = gamma_from_1[w];
\r
3895 for (i = 0; i < row_width; i++, sp += 2)
\r
3897 png_byte a = *(sp + 1);
\r
3900 *sp = (png_byte)png_ptr->background.gray;
\r
3902 else if (a < 0xff)
\r
3903 png_composite(*sp, *sp, a, png_ptr->background_1.gray);
\r
3907 else /* if (png_ptr->bit_depth == 16) */
\r
3909 #ifdef PNG_READ_GAMMA_SUPPORTED
\r
3910 if (gamma_16 != NULL && gamma_16_from_1 != NULL &&
\r
3911 gamma_16_to_1 != NULL)
\r
3914 for (i = 0; i < row_width; i++, sp += 4)
\r
3916 png_uint_16 a = (png_uint_16)(((*(sp + 2)) << 8)
\r
3919 if (a == (png_uint_16)0xffff)
\r
3923 v = gamma_16[*(sp + 1) >> gamma_shift][*sp];
\r
3924 *sp = (png_byte)((v >> 8) & 0xff);
\r
3925 *(sp + 1) = (png_byte)(v & 0xff);
\r
3930 /* Background is already in screen gamma */
\r
3931 *sp = (png_byte)((png_ptr->background.gray >> 8) & 0xff);
\r
3932 *(sp + 1) = (png_byte)(png_ptr->background.gray & 0xff);
\r
3937 png_uint_16 g, v, w;
\r
3939 g = gamma_16_to_1[*(sp + 1) >> gamma_shift][*sp];
\r
3940 png_composite_16(v, g, a, png_ptr->background_1.gray);
\r
3944 w = gamma_16_from_1[(v&0xff) >> gamma_shift][v >> 8];
\r
3945 *sp = (png_byte)((w >> 8) & 0xff);
\r
3946 *(sp + 1) = (png_byte)(w & 0xff);
\r
3954 for (i = 0; i < row_width; i++, sp += 4)
\r
3956 png_uint_16 a = (png_uint_16)(((*(sp + 2)) << 8)
\r
3961 *sp = (png_byte)((png_ptr->background.gray >> 8) & 0xff);
\r
3962 *(sp + 1) = (png_byte)(png_ptr->background.gray & 0xff);
\r
3965 else if (a < 0xffff)
\r
3969 g = (png_uint_16)(((*sp) << 8) + *(sp + 1));
\r
3970 png_composite_16(v, g, a, png_ptr->background_1.gray);
\r
3971 *sp = (png_byte)((v >> 8) & 0xff);
\r
3972 *(sp + 1) = (png_byte)(v & 0xff);
\r
3980 case PNG_COLOR_TYPE_RGB_ALPHA:
\r
3982 if (row_info->bit_depth == 8)
\r
3984 #ifdef PNG_READ_GAMMA_SUPPORTED
\r
3985 if (gamma_to_1 != NULL && gamma_from_1 != NULL &&
\r
3986 gamma_table != NULL)
\r
3989 for (i = 0; i < row_width; i++, sp += 4)
\r
3991 png_byte a = *(sp + 3);
\r
3995 *sp = gamma_table[*sp];
\r
3996 *(sp + 1) = gamma_table[*(sp + 1)];
\r
3997 *(sp + 2) = gamma_table[*(sp + 2)];
\r
4002 /* Background is already in screen gamma */
\r
4003 *sp = (png_byte)png_ptr->background.red;
\r
4004 *(sp + 1) = (png_byte)png_ptr->background.green;
\r
4005 *(sp + 2) = (png_byte)png_ptr->background.blue;
\r
4012 v = gamma_to_1[*sp];
\r
4013 png_composite(w, v, a, png_ptr->background_1.red);
\r
4014 if (!optimize) w = gamma_from_1[w];
\r
4017 v = gamma_to_1[*(sp + 1)];
\r
4018 png_composite(w, v, a, png_ptr->background_1.green);
\r
4019 if (!optimize) w = gamma_from_1[w];
\r
4022 v = gamma_to_1[*(sp + 2)];
\r
4023 png_composite(w, v, a, png_ptr->background_1.blue);
\r
4024 if (!optimize) w = gamma_from_1[w];
\r
4033 for (i = 0; i < row_width; i++, sp += 4)
\r
4035 png_byte a = *(sp + 3);
\r
4039 *sp = (png_byte)png_ptr->background.red;
\r
4040 *(sp + 1) = (png_byte)png_ptr->background.green;
\r
4041 *(sp + 2) = (png_byte)png_ptr->background.blue;
\r
4044 else if (a < 0xff)
\r
4046 png_composite(*sp, *sp, a, png_ptr->background.red);
\r
4048 png_composite(*(sp + 1), *(sp + 1), a,
\r
4049 png_ptr->background.green);
\r
4051 png_composite(*(sp + 2), *(sp + 2), a,
\r
4052 png_ptr->background.blue);
\r
4057 else /* if (row_info->bit_depth == 16) */
\r
4059 #ifdef PNG_READ_GAMMA_SUPPORTED
\r
4060 if (gamma_16 != NULL && gamma_16_from_1 != NULL &&
\r
4061 gamma_16_to_1 != NULL)
\r
4064 for (i = 0; i < row_width; i++, sp += 8)
\r
4066 png_uint_16 a = (png_uint_16)(((png_uint_16)(*(sp + 6))
\r
4067 << 8) + (png_uint_16)(*(sp + 7)));
\r
4069 if (a == (png_uint_16)0xffff)
\r
4073 v = gamma_16[*(sp + 1) >> gamma_shift][*sp];
\r
4074 *sp = (png_byte)((v >> 8) & 0xff);
\r
4075 *(sp + 1) = (png_byte)(v & 0xff);
\r
4077 v = gamma_16[*(sp + 3) >> gamma_shift][*(sp + 2)];
\r
4078 *(sp + 2) = (png_byte)((v >> 8) & 0xff);
\r
4079 *(sp + 3) = (png_byte)(v & 0xff);
\r
4081 v = gamma_16[*(sp + 5) >> gamma_shift][*(sp + 4)];
\r
4082 *(sp + 4) = (png_byte)((v >> 8) & 0xff);
\r
4083 *(sp + 5) = (png_byte)(v & 0xff);
\r
4088 /* Background is already in screen gamma */
\r
4089 *sp = (png_byte)((png_ptr->background.red >> 8) & 0xff);
\r
4090 *(sp + 1) = (png_byte)(png_ptr->background.red & 0xff);
\r
4091 *(sp + 2) = (png_byte)((png_ptr->background.green >> 8) & 0xff);
\r
4092 *(sp + 3) = (png_byte)(png_ptr->background.green & 0xff);
\r
4093 *(sp + 4) = (png_byte)((png_ptr->background.blue >> 8) & 0xff);
\r
4094 *(sp + 5) = (png_byte)(png_ptr->background.blue & 0xff);
\r
4101 v = gamma_16_to_1[*(sp + 1) >> gamma_shift][*sp];
\r
4102 png_composite_16(w, v, a, png_ptr->background_1.red);
\r
4104 w = gamma_16_from_1[((w&0xff) >> gamma_shift)][w >> 8];
\r
4105 *sp = (png_byte)((w >> 8) & 0xff);
\r
4106 *(sp + 1) = (png_byte)(w & 0xff);
\r
4108 v = gamma_16_to_1[*(sp + 3) >> gamma_shift][*(sp + 2)];
\r
4109 png_composite_16(w, v, a, png_ptr->background_1.green);
\r
4111 w = gamma_16_from_1[((w&0xff) >> gamma_shift)][w >> 8];
\r
4113 *(sp + 2) = (png_byte)((w >> 8) & 0xff);
\r
4114 *(sp + 3) = (png_byte)(w & 0xff);
\r
4116 v = gamma_16_to_1[*(sp + 5) >> gamma_shift][*(sp + 4)];
\r
4117 png_composite_16(w, v, a, png_ptr->background_1.blue);
\r
4119 w = gamma_16_from_1[((w&0xff) >> gamma_shift)][w >> 8];
\r
4121 *(sp + 4) = (png_byte)((w >> 8) & 0xff);
\r
4122 *(sp + 5) = (png_byte)(w & 0xff);
\r
4131 for (i = 0; i < row_width; i++, sp += 8)
\r
4133 png_uint_16 a = (png_uint_16)(((png_uint_16)(*(sp + 6))
\r
4134 << 8) + (png_uint_16)(*(sp + 7)));
\r
4138 *sp = (png_byte)((png_ptr->background.red >> 8) & 0xff);
\r
4139 *(sp + 1) = (png_byte)(png_ptr->background.red & 0xff);
\r
4140 *(sp + 2) = (png_byte)((png_ptr->background.green >> 8) & 0xff);
\r
4141 *(sp + 3) = (png_byte)(png_ptr->background.green & 0xff);
\r
4142 *(sp + 4) = (png_byte)((png_ptr->background.blue >> 8) & 0xff);
\r
4143 *(sp + 5) = (png_byte)(png_ptr->background.blue & 0xff);
\r
4146 else if (a < 0xffff)
\r
4150 png_uint_16 r = (png_uint_16)(((*sp) << 8) + *(sp + 1));
\r
4151 png_uint_16 g = (png_uint_16)(((*(sp + 2)) << 8)
\r
4153 png_uint_16 b = (png_uint_16)(((*(sp + 4)) << 8)
\r
4156 png_composite_16(v, r, a, png_ptr->background.red);
\r
4157 *sp = (png_byte)((v >> 8) & 0xff);
\r
4158 *(sp + 1) = (png_byte)(v & 0xff);
\r
4160 png_composite_16(v, g, a, png_ptr->background.green);
\r
4161 *(sp + 2) = (png_byte)((v >> 8) & 0xff);
\r
4162 *(sp + 3) = (png_byte)(v & 0xff);
\r
4164 png_composite_16(v, b, a, png_ptr->background.blue);
\r
4165 *(sp + 4) = (png_byte)((v >> 8) & 0xff);
\r
4166 *(sp + 5) = (png_byte)(v & 0xff);
\r
4179 #endif /* PNG_READ_BACKGROUND_SUPPORTED || PNG_READ_ALPHA_MODE_SUPPORTED */
\r
4181 #ifdef PNG_READ_GAMMA_SUPPORTED
\r
4182 /* Gamma correct the image, avoiding the alpha channel. Make sure
\r
4183 * you do this after you deal with the transparency issue on grayscale
\r
4184 * or RGB images. If your bit depth is 8, use gamma_table, if it
\r
4185 * is 16, use gamma_16_table and gamma_shift. Build these with
\r
4186 * build_gamma_table().
\r
4188 void /* PRIVATE */
\r
4189 png_do_gamma(png_row_infop row_info, png_bytep row, png_structp png_ptr)
\r
4191 png_const_bytep gamma_table = png_ptr->gamma_table;
\r
4192 png_const_uint_16pp gamma_16_table = png_ptr->gamma_16_table;
\r
4193 int gamma_shift = png_ptr->gamma_shift;
\r
4197 png_uint_32 row_width=row_info->width;
\r
4199 png_debug(1, "in png_do_gamma");
\r
4201 if (((row_info->bit_depth <= 8 && gamma_table != NULL) ||
\r
4202 (row_info->bit_depth == 16 && gamma_16_table != NULL)))
\r
4204 switch (row_info->color_type)
\r
4206 case PNG_COLOR_TYPE_RGB:
\r
4208 if (row_info->bit_depth == 8)
\r
4211 for (i = 0; i < row_width; i++)
\r
4213 *sp = gamma_table[*sp];
\r
4215 *sp = gamma_table[*sp];
\r
4217 *sp = gamma_table[*sp];
\r
4222 else /* if (row_info->bit_depth == 16) */
\r
4225 for (i = 0; i < row_width; i++)
\r
4229 v = gamma_16_table[*(sp + 1) >> gamma_shift][*sp];
\r
4230 *sp = (png_byte)((v >> 8) & 0xff);
\r
4231 *(sp + 1) = (png_byte)(v & 0xff);
\r
4234 v = gamma_16_table[*(sp + 1) >> gamma_shift][*sp];
\r
4235 *sp = (png_byte)((v >> 8) & 0xff);
\r
4236 *(sp + 1) = (png_byte)(v & 0xff);
\r
4239 v = gamma_16_table[*(sp + 1) >> gamma_shift][*sp];
\r
4240 *sp = (png_byte)((v >> 8) & 0xff);
\r
4241 *(sp + 1) = (png_byte)(v & 0xff);
\r
4248 case PNG_COLOR_TYPE_RGB_ALPHA:
\r
4250 if (row_info->bit_depth == 8)
\r
4253 for (i = 0; i < row_width; i++)
\r
4255 *sp = gamma_table[*sp];
\r
4258 *sp = gamma_table[*sp];
\r
4261 *sp = gamma_table[*sp];
\r
4268 else /* if (row_info->bit_depth == 16) */
\r
4271 for (i = 0; i < row_width; i++)
\r
4273 png_uint_16 v = gamma_16_table[*(sp + 1) >> gamma_shift][*sp];
\r
4274 *sp = (png_byte)((v >> 8) & 0xff);
\r
4275 *(sp + 1) = (png_byte)(v & 0xff);
\r
4278 v = gamma_16_table[*(sp + 1) >> gamma_shift][*sp];
\r
4279 *sp = (png_byte)((v >> 8) & 0xff);
\r
4280 *(sp + 1) = (png_byte)(v & 0xff);
\r
4283 v = gamma_16_table[*(sp + 1) >> gamma_shift][*sp];
\r
4284 *sp = (png_byte)((v >> 8) & 0xff);
\r
4285 *(sp + 1) = (png_byte)(v & 0xff);
\r
4292 case PNG_COLOR_TYPE_GRAY_ALPHA:
\r
4294 if (row_info->bit_depth == 8)
\r
4297 for (i = 0; i < row_width; i++)
\r
4299 *sp = gamma_table[*sp];
\r
4304 else /* if (row_info->bit_depth == 16) */
\r
4307 for (i = 0; i < row_width; i++)
\r
4309 png_uint_16 v = gamma_16_table[*(sp + 1) >> gamma_shift][*sp];
\r
4310 *sp = (png_byte)((v >> 8) & 0xff);
\r
4311 *(sp + 1) = (png_byte)(v & 0xff);
\r
4318 case PNG_COLOR_TYPE_GRAY:
\r
4320 if (row_info->bit_depth == 2)
\r
4323 for (i = 0; i < row_width; i += 4)
\r
4325 int a = *sp & 0xc0;
\r
4326 int b = *sp & 0x30;
\r
4327 int c = *sp & 0x0c;
\r
4328 int d = *sp & 0x03;
\r
4331 ((((int)gamma_table[a|(a>>2)|(a>>4)|(a>>6)]) ) & 0xc0)|
\r
4332 ((((int)gamma_table[(b<<2)|b|(b>>2)|(b>>4)])>>2) & 0x30)|
\r
4333 ((((int)gamma_table[(c<<4)|(c<<2)|c|(c>>2)])>>4) & 0x0c)|
\r
4334 ((((int)gamma_table[(d<<6)|(d<<4)|(d<<2)|d])>>6) ));
\r
4339 if (row_info->bit_depth == 4)
\r
4342 for (i = 0; i < row_width; i += 2)
\r
4344 int msb = *sp & 0xf0;
\r
4345 int lsb = *sp & 0x0f;
\r
4347 *sp = (png_byte)((((int)gamma_table[msb | (msb >> 4)]) & 0xf0)
\r
4348 | (((int)gamma_table[(lsb << 4) | lsb]) >> 4));
\r
4353 else if (row_info->bit_depth == 8)
\r
4356 for (i = 0; i < row_width; i++)
\r
4358 *sp = gamma_table[*sp];
\r
4363 else if (row_info->bit_depth == 16)
\r
4366 for (i = 0; i < row_width; i++)
\r
4368 png_uint_16 v = gamma_16_table[*(sp + 1) >> gamma_shift][*sp];
\r
4369 *sp = (png_byte)((v >> 8) & 0xff);
\r
4370 *(sp + 1) = (png_byte)(v & 0xff);
\r
4384 #ifdef PNG_READ_ALPHA_MODE_SUPPORTED
\r
4385 /* Encode the alpha channel to the output gamma (the input channel is always
\r
4386 * linear.) Called only with color types that have an alpha channel. Needs the
\r
4389 void /* PRIVATE */
\r
4390 png_do_encode_alpha(png_row_infop row_info, png_bytep row, png_structp png_ptr)
\r
4392 png_uint_32 row_width = row_info->width;
\r
4394 png_debug(1, "in png_do_encode_alpha");
\r
4396 if (row_info->color_type & PNG_COLOR_MASK_ALPHA)
\r
4398 if (row_info->bit_depth == 8)
\r
4400 PNG_CONST png_bytep table = png_ptr->gamma_from_1;
\r
4402 if (table != NULL)
\r
4404 PNG_CONST int step =
\r
4405 (row_info->color_type & PNG_COLOR_MASK_COLOR) ? 4 : 2;
\r
4407 /* The alpha channel is the last component: */
\r
4410 for (; row_width > 0; --row_width, row += step)
\r
4411 *row = table[*row];
\r
4417 else if (row_info->bit_depth == 16)
\r
4419 PNG_CONST png_uint_16pp table = png_ptr->gamma_16_from_1;
\r
4420 PNG_CONST int gamma_shift = png_ptr->gamma_shift;
\r
4422 if (table != NULL)
\r
4424 PNG_CONST int step =
\r
4425 (row_info->color_type & PNG_COLOR_MASK_COLOR) ? 8 : 4;
\r
4427 /* The alpha channel is the last component: */
\r
4430 for (; row_width > 0; --row_width, row += step)
\r
4434 v = table[*(row + 1) >> gamma_shift][*row];
\r
4435 *row = (png_byte)((v >> 8) & 0xff);
\r
4436 *(row + 1) = (png_byte)(v & 0xff);
\r
4444 /* Only get to here if called with a weird row_info; no harm has been done,
\r
4445 * so just issue a warning.
\r
4447 png_warning(png_ptr, "png_do_encode_alpha: unexpected call");
\r
4451 #ifdef PNG_READ_EXPAND_SUPPORTED
\r
4452 /* Expands a palette row to an RGB or RGBA row depending
\r
4453 * upon whether you supply trans and num_trans.
\r
4455 void /* PRIVATE */
\r
4456 png_do_expand_palette(png_row_infop row_info, png_bytep row,
\r
4457 png_const_colorp palette, png_const_bytep trans_alpha, int num_trans)
\r
4462 png_uint_32 row_width=row_info->width;
\r
4464 png_debug(1, "in png_do_expand_palette");
\r
4466 if (row_info->color_type == PNG_COLOR_TYPE_PALETTE)
\r
4468 if (row_info->bit_depth < 8)
\r
4470 switch (row_info->bit_depth)
\r
4474 sp = row + (png_size_t)((row_width - 1) >> 3);
\r
4475 dp = row + (png_size_t)row_width - 1;
\r
4476 shift = 7 - (int)((row_width + 7) & 0x07);
\r
4477 for (i = 0; i < row_width; i++)
\r
4479 if ((*sp >> shift) & 0x01)
\r
4501 sp = row + (png_size_t)((row_width - 1) >> 2);
\r
4502 dp = row + (png_size_t)row_width - 1;
\r
4503 shift = (int)((3 - ((row_width + 3) & 0x03)) << 1);
\r
4504 for (i = 0; i < row_width; i++)
\r
4506 value = (*sp >> shift) & 0x03;
\r
4507 *dp = (png_byte)value;
\r
4524 sp = row + (png_size_t)((row_width - 1) >> 1);
\r
4525 dp = row + (png_size_t)row_width - 1;
\r
4526 shift = (int)((row_width & 0x01) << 2);
\r
4527 for (i = 0; i < row_width; i++)
\r
4529 value = (*sp >> shift) & 0x0f;
\r
4530 *dp = (png_byte)value;
\r
4548 row_info->bit_depth = 8;
\r
4549 row_info->pixel_depth = 8;
\r
4550 row_info->rowbytes = row_width;
\r
4553 if (row_info->bit_depth == 8)
\r
4556 if (num_trans > 0)
\r
4558 sp = row + (png_size_t)row_width - 1;
\r
4559 dp = row + (png_size_t)(row_width << 2) - 1;
\r
4561 for (i = 0; i < row_width; i++)
\r
4563 if ((int)(*sp) >= num_trans)
\r
4567 *dp-- = trans_alpha[*sp];
\r
4569 *dp-- = palette[*sp].blue;
\r
4570 *dp-- = palette[*sp].green;
\r
4571 *dp-- = palette[*sp].red;
\r
4574 row_info->bit_depth = 8;
\r
4575 row_info->pixel_depth = 32;
\r
4576 row_info->rowbytes = row_width * 4;
\r
4577 row_info->color_type = 6;
\r
4578 row_info->channels = 4;
\r
4583 sp = row + (png_size_t)row_width - 1;
\r
4584 dp = row + (png_size_t)(row_width * 3) - 1;
\r
4586 for (i = 0; i < row_width; i++)
\r
4588 *dp-- = palette[*sp].blue;
\r
4589 *dp-- = palette[*sp].green;
\r
4590 *dp-- = palette[*sp].red;
\r
4594 row_info->bit_depth = 8;
\r
4595 row_info->pixel_depth = 24;
\r
4596 row_info->rowbytes = row_width * 3;
\r
4597 row_info->color_type = 2;
\r
4598 row_info->channels = 3;
\r
4605 /* If the bit depth < 8, it is expanded to 8. Also, if the already
\r
4606 * expanded transparency value is supplied, an alpha channel is built.
\r
4608 void /* PRIVATE */
\r
4609 png_do_expand(png_row_infop row_info, png_bytep row,
\r
4610 png_const_color_16p trans_color)
\r
4615 png_uint_32 row_width=row_info->width;
\r
4617 png_debug(1, "in png_do_expand");
\r
4620 if (row_info->color_type == PNG_COLOR_TYPE_GRAY)
\r
4622 png_uint_16 gray = (png_uint_16)(trans_color ? trans_color->gray : 0);
\r
4624 if (row_info->bit_depth < 8)
\r
4626 switch (row_info->bit_depth)
\r
4630 gray = (png_uint_16)((gray & 0x01) * 0xff);
\r
4631 sp = row + (png_size_t)((row_width - 1) >> 3);
\r
4632 dp = row + (png_size_t)row_width - 1;
\r
4633 shift = 7 - (int)((row_width + 7) & 0x07);
\r
4634 for (i = 0; i < row_width; i++)
\r
4636 if ((*sp >> shift) & 0x01)
\r
4658 gray = (png_uint_16)((gray & 0x03) * 0x55);
\r
4659 sp = row + (png_size_t)((row_width - 1) >> 2);
\r
4660 dp = row + (png_size_t)row_width - 1;
\r
4661 shift = (int)((3 - ((row_width + 3) & 0x03)) << 1);
\r
4662 for (i = 0; i < row_width; i++)
\r
4664 value = (*sp >> shift) & 0x03;
\r
4665 *dp = (png_byte)(value | (value << 2) | (value << 4) |
\r
4683 gray = (png_uint_16)((gray & 0x0f) * 0x11);
\r
4684 sp = row + (png_size_t)((row_width - 1) >> 1);
\r
4685 dp = row + (png_size_t)row_width - 1;
\r
4686 shift = (int)((1 - ((row_width + 1) & 0x01)) << 2);
\r
4687 for (i = 0; i < row_width; i++)
\r
4689 value = (*sp >> shift) & 0x0f;
\r
4690 *dp = (png_byte)(value | (value << 4));
\r
4709 row_info->bit_depth = 8;
\r
4710 row_info->pixel_depth = 8;
\r
4711 row_info->rowbytes = row_width;
\r
4714 if (trans_color != NULL)
\r
4716 if (row_info->bit_depth == 8)
\r
4718 gray = gray & 0xff;
\r
4719 sp = row + (png_size_t)row_width - 1;
\r
4720 dp = row + (png_size_t)(row_width << 1) - 1;
\r
4722 for (i = 0; i < row_width; i++)
\r
4734 else if (row_info->bit_depth == 16)
\r
4736 png_byte gray_high = (png_byte)((gray >> 8) & 0xff);
\r
4737 png_byte gray_low = (png_byte)(gray & 0xff);
\r
4738 sp = row + row_info->rowbytes - 1;
\r
4739 dp = row + (row_info->rowbytes << 1) - 1;
\r
4740 for (i = 0; i < row_width; i++)
\r
4742 if (*(sp - 1) == gray_high && *(sp) == gray_low)
\r
4759 row_info->color_type = PNG_COLOR_TYPE_GRAY_ALPHA;
\r
4760 row_info->channels = 2;
\r
4761 row_info->pixel_depth = (png_byte)(row_info->bit_depth << 1);
\r
4762 row_info->rowbytes = PNG_ROWBYTES(row_info->pixel_depth,
\r
4766 else if (row_info->color_type == PNG_COLOR_TYPE_RGB && trans_color)
\r
4768 if (row_info->bit_depth == 8)
\r
4770 png_byte red = (png_byte)(trans_color->red & 0xff);
\r
4771 png_byte green = (png_byte)(trans_color->green & 0xff);
\r
4772 png_byte blue = (png_byte)(trans_color->blue & 0xff);
\r
4773 sp = row + (png_size_t)row_info->rowbytes - 1;
\r
4774 dp = row + (png_size_t)(row_width << 2) - 1;
\r
4775 for (i = 0; i < row_width; i++)
\r
4777 if (*(sp - 2) == red && *(sp - 1) == green && *(sp) == blue)
\r
4788 else if (row_info->bit_depth == 16)
\r
4790 png_byte red_high = (png_byte)((trans_color->red >> 8) & 0xff);
\r
4791 png_byte green_high = (png_byte)((trans_color->green >> 8) & 0xff);
\r
4792 png_byte blue_high = (png_byte)((trans_color->blue >> 8) & 0xff);
\r
4793 png_byte red_low = (png_byte)(trans_color->red & 0xff);
\r
4794 png_byte green_low = (png_byte)(trans_color->green & 0xff);
\r
4795 png_byte blue_low = (png_byte)(trans_color->blue & 0xff);
\r
4796 sp = row + row_info->rowbytes - 1;
\r
4797 dp = row + (png_size_t)(row_width << 3) - 1;
\r
4798 for (i = 0; i < row_width; i++)
\r
4800 if (*(sp - 5) == red_high &&
\r
4801 *(sp - 4) == red_low &&
\r
4802 *(sp - 3) == green_high &&
\r
4803 *(sp - 2) == green_low &&
\r
4804 *(sp - 1) == blue_high &&
\r
4805 *(sp ) == blue_low)
\r
4825 row_info->color_type = PNG_COLOR_TYPE_RGB_ALPHA;
\r
4826 row_info->channels = 4;
\r
4827 row_info->pixel_depth = (png_byte)(row_info->bit_depth << 2);
\r
4828 row_info->rowbytes = PNG_ROWBYTES(row_info->pixel_depth, row_width);
\r
4834 #ifdef PNG_READ_EXPAND_16_SUPPORTED
\r
4835 /* If the bit depth is 8 and the color type is not a palette type expand the
\r
4836 * whole row to 16 bits. Has no effect otherwise.
\r
4838 void /* PRIVATE */
\r
4839 png_do_expand_16(png_row_infop row_info, png_bytep row)
\r
4841 if (row_info->bit_depth == 8 &&
\r
4842 row_info->color_type != PNG_COLOR_TYPE_PALETTE)
\r
4844 /* The row have a sequence of bytes containing [0..255] and we need
\r
4845 * to turn it into another row containing [0..65535], to do this we
\r
4848 * (input / 255) * 65535
\r
4850 * Which happens to be exactly input * 257 and this can be achieved
\r
4851 * simply by byte replication in place (copying backwards).
\r
4853 png_byte *sp = row + row_info->rowbytes; /* source, last byte + 1 */
\r
4854 png_byte *dp = sp + row_info->rowbytes; /* destination, end + 1 */
\r
4856 dp[-2] = dp[-1] = *--sp, dp -= 2;
\r
4858 row_info->rowbytes *= 2;
\r
4859 row_info->bit_depth = 16;
\r
4860 row_info->pixel_depth = (png_byte)(row_info->channels * 16);
\r
4865 #ifdef PNG_READ_QUANTIZE_SUPPORTED
\r
4866 void /* PRIVATE */
\r
4867 png_do_quantize(png_row_infop row_info, png_bytep row,
\r
4868 png_const_bytep palette_lookup, png_const_bytep quantize_lookup)
\r
4872 png_uint_32 row_width=row_info->width;
\r
4874 png_debug(1, "in png_do_quantize");
\r
4876 if (row_info->bit_depth == 8)
\r
4878 if (row_info->color_type == PNG_COLOR_TYPE_RGB && palette_lookup)
\r
4883 for (i = 0; i < row_width; i++)
\r
4889 /* This looks real messy, but the compiler will reduce
\r
4890 * it down to a reasonable formula. For example, with
\r
4891 * 5 bits per color, we get:
\r
4892 * p = (((r >> 3) & 0x1f) << 10) |
\r
4893 * (((g >> 3) & 0x1f) << 5) |
\r
4894 * ((b >> 3) & 0x1f);
\r
4896 p = (((r >> (8 - PNG_QUANTIZE_RED_BITS)) &
\r
4897 ((1 << PNG_QUANTIZE_RED_BITS) - 1)) <<
\r
4898 (PNG_QUANTIZE_GREEN_BITS + PNG_QUANTIZE_BLUE_BITS)) |
\r
4899 (((g >> (8 - PNG_QUANTIZE_GREEN_BITS)) &
\r
4900 ((1 << PNG_QUANTIZE_GREEN_BITS) - 1)) <<
\r
4901 (PNG_QUANTIZE_BLUE_BITS)) |
\r
4902 ((b >> (8 - PNG_QUANTIZE_BLUE_BITS)) &
\r
4903 ((1 << PNG_QUANTIZE_BLUE_BITS) - 1));
\r
4905 *dp++ = palette_lookup[p];
\r
4908 row_info->color_type = PNG_COLOR_TYPE_PALETTE;
\r
4909 row_info->channels = 1;
\r
4910 row_info->pixel_depth = row_info->bit_depth;
\r
4911 row_info->rowbytes = PNG_ROWBYTES(row_info->pixel_depth, row_width);
\r
4914 else if (row_info->color_type == PNG_COLOR_TYPE_RGB_ALPHA &&
\r
4915 palette_lookup != NULL)
\r
4920 for (i = 0; i < row_width; i++)
\r
4927 p = (((r >> (8 - PNG_QUANTIZE_RED_BITS)) &
\r
4928 ((1 << PNG_QUANTIZE_RED_BITS) - 1)) <<
\r
4929 (PNG_QUANTIZE_GREEN_BITS + PNG_QUANTIZE_BLUE_BITS)) |
\r
4930 (((g >> (8 - PNG_QUANTIZE_GREEN_BITS)) &
\r
4931 ((1 << PNG_QUANTIZE_GREEN_BITS) - 1)) <<
\r
4932 (PNG_QUANTIZE_BLUE_BITS)) |
\r
4933 ((b >> (8 - PNG_QUANTIZE_BLUE_BITS)) &
\r
4934 ((1 << PNG_QUANTIZE_BLUE_BITS) - 1));
\r
4936 *dp++ = palette_lookup[p];
\r
4939 row_info->color_type = PNG_COLOR_TYPE_PALETTE;
\r
4940 row_info->channels = 1;
\r
4941 row_info->pixel_depth = row_info->bit_depth;
\r
4942 row_info->rowbytes = PNG_ROWBYTES(row_info->pixel_depth, row_width);
\r
4945 else if (row_info->color_type == PNG_COLOR_TYPE_PALETTE &&
\r
4950 for (i = 0; i < row_width; i++, sp++)
\r
4952 *sp = quantize_lookup[*sp];
\r
4957 #endif /* PNG_READ_QUANTIZE_SUPPORTED */
\r
4958 #endif /* PNG_READ_TRANSFORMS_SUPPORTED */
\r
4960 #ifdef PNG_MNG_FEATURES_SUPPORTED
\r
4961 /* Undoes intrapixel differencing */
\r
4962 void /* PRIVATE */
\r
4963 png_do_read_intrapixel(png_row_infop row_info, png_bytep row)
\r
4965 png_debug(1, "in png_do_read_intrapixel");
\r
4968 (row_info->color_type & PNG_COLOR_MASK_COLOR))
\r
4970 int bytes_per_pixel;
\r
4971 png_uint_32 row_width = row_info->width;
\r
4973 if (row_info->bit_depth == 8)
\r
4978 if (row_info->color_type == PNG_COLOR_TYPE_RGB)
\r
4979 bytes_per_pixel = 3;
\r
4981 else if (row_info->color_type == PNG_COLOR_TYPE_RGB_ALPHA)
\r
4982 bytes_per_pixel = 4;
\r
4987 for (i = 0, rp = row; i < row_width; i++, rp += bytes_per_pixel)
\r
4989 *(rp) = (png_byte)((256 + *rp + *(rp + 1)) & 0xff);
\r
4990 *(rp+2) = (png_byte)((256 + *(rp + 2) + *(rp + 1)) & 0xff);
\r
4993 else if (row_info->bit_depth == 16)
\r
4998 if (row_info->color_type == PNG_COLOR_TYPE_RGB)
\r
4999 bytes_per_pixel = 6;
\r
5001 else if (row_info->color_type == PNG_COLOR_TYPE_RGB_ALPHA)
\r
5002 bytes_per_pixel = 8;
\r
5007 for (i = 0, rp = row; i < row_width; i++, rp += bytes_per_pixel)
\r
5009 png_uint_32 s0 = (*(rp ) << 8) | *(rp + 1);
\r
5010 png_uint_32 s1 = (*(rp + 2) << 8) | *(rp + 3);
\r
5011 png_uint_32 s2 = (*(rp + 4) << 8) | *(rp + 5);
\r
5012 png_uint_32 red = (s0 + s1 + 65536) & 0xffff;
\r
5013 png_uint_32 blue = (s2 + s1 + 65536) & 0xffff;
\r
5014 *(rp ) = (png_byte)((red >> 8) & 0xff);
\r
5015 *(rp + 1) = (png_byte)(red & 0xff);
\r
5016 *(rp + 4) = (png_byte)((blue >> 8) & 0xff);
\r
5017 *(rp + 5) = (png_byte)(blue & 0xff);
\r
5022 #endif /* PNG_MNG_FEATURES_SUPPORTED */
\r
5023 #endif /* PNG_READ_SUPPORTED */
\r
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