2 * Copyright 2013 The Android Open Source Project
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
8 * http://www.apache.org/licenses/LICENSE-2.0
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
17 #include "Daltonizer.h"
22 Daltonizer::Daltonizer() :
23 mType(deuteranomaly), mMode(simulation), mDirty(true) {
26 Daltonizer::~Daltonizer() {
29 void Daltonizer::setType(Daltonizer::ColorBlindnessTypes type) {
36 void Daltonizer::setMode(Daltonizer::Mode mode) {
43 const mat4& Daltonizer::operator()() {
48 return mColorTransform;
51 void Daltonizer::update() {
52 // converts a linear RGB color to the XYZ space
53 const mat4 rgb2xyz( 0.4124, 0.2126, 0.0193, 0,
54 0.3576, 0.7152, 0.1192, 0,
55 0.1805, 0.0722, 0.9505, 0,
58 // converts a XYZ color to the LMS space.
59 const mat4 xyz2lms( 0.7328,-0.7036, 0.0030, 0,
60 0.4296, 1.6975, 0.0136, 0,
61 -0.1624, 0.0061, 0.9834, 0,
64 // Direct conversion from linear RGB to LMS
65 const mat4 rgb2lms(xyz2lms*rgb2xyz);
67 // And back from LMS to linear RGB
68 const mat4 lms2rgb(inverse(rgb2lms));
70 // To simulate color blindness we need to "remove" the data lost by the absence of
71 // a cone. This cannot be done by just zeroing out the corresponding LMS component
72 // because it would create a color outside of the RGB gammut.
73 // Instead we project the color along the axis of the missing component onto a plane
74 // within the RGB gammut:
75 // - since the projection happens along the axis of the missing component, a
76 // color blind viewer perceives the projected color the same.
77 // - We use the plane defined by 3 points in LMS space: black, white and
78 // blue and red for protanopia/deuteranopia and tritanopia respectively.
81 const vec3& lms_r(rgb2lms[0].rgb);
83 const vec3& lms_b(rgb2lms[2].rgb);
85 const vec3 lms_w((rgb2lms * vec4(1)).rgb);
87 // To find the planes we solve the a*L + b*M + c*S = 0 equation for the LMS values
88 // of the three known points. This equation is trivially solved, and has for
89 // solution the following cross-products:
90 const vec3 p0 = cross(lms_w, lms_b); // protanopia/deuteranopia
91 const vec3 p1 = cross(lms_w, lms_r); // tritanopia
93 // The following 3 matrices perform the projection of a LMS color onto the given plane
94 // along the selected axis
96 // projection for protanopia (L = 0)
97 const mat4 lms2lmsp( 0.0000, 0.0000, 0.0000, 0,
98 -p0.y / p0.x, 1.0000, 0.0000, 0,
99 -p0.z / p0.x, 0.0000, 1.0000, 0,
102 // projection for deuteranopia (M = 0)
103 const mat4 lms2lmsd( 1.0000, -p0.x / p0.y, 0.0000, 0,
104 0.0000, 0.0000, 0.0000, 0,
105 0.0000, -p0.z / p0.y, 1.0000, 0,
108 // projection for tritanopia (S = 0)
109 const mat4 lms2lmst( 1.0000, 0.0000, -p1.x / p1.z, 0,
110 0.0000, 1.0000, -p1.y / p1.z, 0,
111 0.0000, 0.0000, 0.0000, 0,
114 // We will calculate the error between the color and the color viewed by
115 // a color blind user and "spread" this error onto the healthy cones.
116 // The matrices below perform this last step and have been chosen arbitrarily.
118 // The amount of correction can be adjusted here.
120 // error spread for protanopia
121 const mat4 errp( 1.0, 0.7, 0.7, 0,
126 // error spread for deuteranopia
127 const mat4 errd( 1.0, 0.0, 0.0, 0,
132 // error spread for tritanopia
133 const mat4 errt( 1.0, 0.0, 0.0, 0,
140 // And the magic happens here...
141 // We construct the matrix that will perform the whole correction.
143 // simulation: type of color blindness to simulate:
144 // set to either lms2lmsp, lms2lmsd, lms2lmst
147 // correction: type of color blindness correction (should match the simulation above):
148 // set to identity, errp, errd, errt ([0] for simulation only)
154 simulation = lms2lmsp;
155 if (mMode == Daltonizer::correction)
160 simulation = lms2lmsd;
161 if (mMode == Daltonizer::correction)
166 simulation = lms2lmst;
167 if (mMode == Daltonizer::correction)
172 mColorTransform = lms2rgb *
173 (simulation * rgb2lms + correction * (rgb2lms - simulation * rgb2lms));
176 } /* namespace android */