validates :width, :presence => true, :numericality => true, :natural_number => true
validates :height, :presence => true, :numericality => true, :natural_number => true
validates :filesize, :presence => true, :numericality => {:greater_than => 0, :less_than_or_equal_to => 2000000}, :natural_number => true
validates :width, :presence => true, :numericality => true, :natural_number => true
validates :height, :presence => true, :numericality => true, :natural_number => true
validates :filesize, :presence => true, :numericality => {:greater_than => 0, :less_than_or_equal_to => 2000000}, :natural_number => true