1 /* 2 * Copyright 2013 The Android Open Source Project 3 * 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 7 * 8 * http://www.apache.org/licenses/LICENSE-2.0 9 * 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. 15 */ 16 17 #include "Daltonizer.h" 18 #include <math/mat4.h> 19 20 namespace android { 21 22 void Daltonizer::setType(ColorBlindnessType type) { 23 if (type != mType) { 24 mDirty = true; 25 mType = type; 26 } 27 } 28 29 void Daltonizer::setMode(ColorBlindnessMode mode) { 30 if (mode != mMode) { 31 mDirty = true; 32 mMode = mode; 33 } 34 } 35 36 const mat4& Daltonizer::operator()() { 37 if (mDirty) { 38 mDirty = false; 39 update(); 40 } 41 return mColorTransform; 42 } 43 44 void Daltonizer::update() { 45 if (mType == ColorBlindnessType::None) { 46 mColorTransform = mat4(); 47 return; 48 } 49 50 // converts a linear RGB color to the XYZ space 51 const mat4 rgb2xyz( 0.4124, 0.2126, 0.0193, 0, 52 0.3576, 0.7152, 0.1192, 0, 53 0.1805, 0.0722, 0.9505, 0, 54 0 , 0 , 0 , 1); 55 56 // converts a XYZ color to the LMS space. 57 const mat4 xyz2lms( 0.7328,-0.7036, 0.0030, 0, 58 0.4296, 1.6975, 0.0136, 0, 59 -0.1624, 0.0061, 0.9834, 0, 60 0 , 0 , 0 , 1); 61 62 // Direct conversion from linear RGB to LMS 63 const mat4 rgb2lms(xyz2lms*rgb2xyz); 64 65 // And back from LMS to linear RGB 66 const mat4 lms2rgb(inverse(rgb2lms)); 67 68 // To simulate color blindness we need to "remove" the data lost by the absence of 69 // a cone. This cannot be done by just zeroing out the corresponding LMS component 70 // because it would create a color outside of the RGB gammut. 71 // Instead we project the color along the axis of the missing component onto a plane 72 // within the RGB gammut: 73 // - since the projection happens along the axis of the missing component, a 74 // color blind viewer perceives the projected color the same. 75 // - We use the plane defined by 3 points in LMS space: black, white and 76 // blue and red for protanopia/deuteranopia and tritanopia respectively. 77 78 // LMS space red 79 const vec3& lms_r(rgb2lms[0].rgb); 80 // LMS space blue 81 const vec3& lms_b(rgb2lms[2].rgb); 82 // LMS space white 83 const vec3 lms_w((rgb2lms * vec4(1)).rgb); 84 85 // To find the planes we solve the a*L + b*M + c*S = 0 equation for the LMS values 86 // of the three known points. This equation is trivially solved, and has for 87 // solution the following cross-products: 88 const vec3 p0 = cross(lms_w, lms_b); // protanopia/deuteranopia 89 const vec3 p1 = cross(lms_w, lms_r); // tritanopia 90 91 // The following 3 matrices perform the projection of a LMS color onto the given plane 92 // along the selected axis 93 94 // projection for protanopia (L = 0) 95 const mat4 lms2lmsp( 0.0000, 0.0000, 0.0000, 0, 96 -p0.y / p0.x, 1.0000, 0.0000, 0, 97 -p0.z / p0.x, 0.0000, 1.0000, 0, 98 0 , 0 , 0 , 1); 99 100 // projection for deuteranopia (M = 0) 101 const mat4 lms2lmsd( 1.0000, -p0.x / p0.y, 0.0000, 0, 102 0.0000, 0.0000, 0.0000, 0, 103 0.0000, -p0.z / p0.y, 1.0000, 0, 104 0 , 0 , 0 , 1); 105 106 // projection for tritanopia (S = 0) 107 const mat4 lms2lmst( 1.0000, 0.0000, -p1.x / p1.z, 0, 108 0.0000, 1.0000, -p1.y / p1.z, 0, 109 0.0000, 0.0000, 0.0000, 0, 110 0 , 0 , 0 , 1); 111 112 // We will calculate the error between the color and the color viewed by 113 // a color blind user and "spread" this error onto the healthy cones. 114 // The matrices below perform this last step and have been chosen arbitrarily. 115 116 // The amount of correction can be adjusted here. 117 118 // error spread for protanopia 119 const mat4 errp( 1.0, 0.7, 0.7, 0, 120 0.0, 1.0, 0.0, 0, 121 0.0, 0.0, 1.0, 0, 122 0, 0, 0, 1); 123 124 // error spread for deuteranopia 125 const mat4 errd( 1.0, 0.0, 0.0, 0, 126 0.7, 1.0, 0.7, 0, 127 0.0, 0.0, 1.0, 0, 128 0, 0, 0, 1); 129 130 // error spread for tritanopia 131 const mat4 errt( 1.0, 0.0, 0.0, 0, 132 0.0, 1.0, 0.0, 0, 133 0.7, 0.7, 1.0, 0, 134 0, 0, 0, 1); 135 136 // And the magic happens here... 137 // We construct the matrix that will perform the whole correction. 138 139 // simulation: type of color blindness to simulate: 140 // set to either lms2lmsp, lms2lmsd, lms2lmst 141 mat4 simulation; 142 143 // correction: type of color blindness correction (should match the simulation above): 144 // set to identity, errp, errd, errt ([0] for simulation only) 145 mat4 correction(0); 146 147 switch (mType) { 148 case ColorBlindnessType::Protanomaly: 149 simulation = lms2lmsp; 150 if (mMode == ColorBlindnessMode::Correction) 151 correction = errp; 152 break; 153 case ColorBlindnessType::Deuteranomaly: 154 simulation = lms2lmsd; 155 if (mMode == ColorBlindnessMode::Correction) 156 correction = errd; 157 break; 158 case ColorBlindnessType::Tritanomaly: 159 simulation = lms2lmst; 160 if (mMode == ColorBlindnessMode::Correction) 161 correction = errt; 162 break; 163 case ColorBlindnessType::None: 164 // We already caught this at the beginning of the method, but the 165 // compiler doesn't know that 166 break; 167 } 168 169 mColorTransform = lms2rgb * 170 (simulation * rgb2lms + correction * (rgb2lms - simulation * rgb2lms)); 171 } 172 173 } /* namespace android */ 174
