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 // TODO(b/129481165): remove the #pragma below and fix conversion issues
18 #pragma clang diagnostic push
19 #pragma clang diagnostic ignored "-Wconversion"
20
21 #include "Daltonizer.h"
22 #include <math/mat4.h>
23
24 namespace android {
25
setType(ColorBlindnessType type)26 void Daltonizer::setType(ColorBlindnessType type) {
27 if (type != mType) {
28 mDirty = true;
29 mType = type;
30 }
31 }
32
setMode(ColorBlindnessMode mode)33 void Daltonizer::setMode(ColorBlindnessMode mode) {
34 if (mode != mMode) {
35 mDirty = true;
36 mMode = mode;
37 }
38 }
39
operator ()()40 const mat4& Daltonizer::operator()() {
41 if (mDirty) {
42 mDirty = false;
43 update();
44 }
45 return mColorTransform;
46 }
47
update()48 void Daltonizer::update() {
49 if (mType == ColorBlindnessType::None) {
50 mColorTransform = mat4();
51 return;
52 }
53
54 // converts a linear RGB color to the XYZ space
55 const mat4 rgb2xyz( 0.4124, 0.2126, 0.0193, 0,
56 0.3576, 0.7152, 0.1192, 0,
57 0.1805, 0.0722, 0.9505, 0,
58 0 , 0 , 0 , 1);
59
60 // converts a XYZ color to the LMS space.
61 const mat4 xyz2lms( 0.7328,-0.7036, 0.0030, 0,
62 0.4296, 1.6975, 0.0136, 0,
63 -0.1624, 0.0061, 0.9834, 0,
64 0 , 0 , 0 , 1);
65
66 // Direct conversion from linear RGB to LMS
67 const mat4 rgb2lms(xyz2lms*rgb2xyz);
68
69 // And back from LMS to linear RGB
70 const mat4 lms2rgb(inverse(rgb2lms));
71
72 // To simulate color blindness we need to "remove" the data lost by the absence of
73 // a cone. This cannot be done by just zeroing out the corresponding LMS component
74 // because it would create a color outside of the RGB gammut.
75 // Instead we project the color along the axis of the missing component onto a plane
76 // within the RGB gammut:
77 // - since the projection happens along the axis of the missing component, a
78 // color blind viewer perceives the projected color the same.
79 // - We use the plane defined by 3 points in LMS space: black, white and
80 // blue and red for protanopia/deuteranopia and tritanopia respectively.
81
82 // LMS space red
83 const vec3& lms_r(rgb2lms[0].rgb);
84 // LMS space blue
85 const vec3& lms_b(rgb2lms[2].rgb);
86 // LMS space white
87 const vec3 lms_w((rgb2lms * vec4(1)).rgb);
88
89 // To find the planes we solve the a*L + b*M + c*S = 0 equation for the LMS values
90 // of the three known points. This equation is trivially solved, and has for
91 // solution the following cross-products:
92 const vec3 p0 = cross(lms_w, lms_b); // protanopia/deuteranopia
93 const vec3 p1 = cross(lms_w, lms_r); // tritanopia
94
95 // The following 3 matrices perform the projection of a LMS color onto the given plane
96 // along the selected axis
97
98 // projection for protanopia (L = 0)
99 const mat4 lms2lmsp( 0.0000, 0.0000, 0.0000, 0,
100 -p0.y / p0.x, 1.0000, 0.0000, 0,
101 -p0.z / p0.x, 0.0000, 1.0000, 0,
102 0 , 0 , 0 , 1);
103
104 // projection for deuteranopia (M = 0)
105 const mat4 lms2lmsd( 1.0000, -p0.x / p0.y, 0.0000, 0,
106 0.0000, 0.0000, 0.0000, 0,
107 0.0000, -p0.z / p0.y, 1.0000, 0,
108 0 , 0 , 0 , 1);
109
110 // projection for tritanopia (S = 0)
111 const mat4 lms2lmst( 1.0000, 0.0000, -p1.x / p1.z, 0,
112 0.0000, 1.0000, -p1.y / p1.z, 0,
113 0.0000, 0.0000, 0.0000, 0,
114 0 , 0 , 0 , 1);
115
116 // We will calculate the error between the color and the color viewed by
117 // a color blind user and "spread" this error onto the healthy cones.
118 // The matrices below perform this last step and have been chosen arbitrarily.
119
120 // The amount of correction can be adjusted here.
121
122 // error spread for protanopia
123 const mat4 errp( 1.0, 0.7, 0.7, 0,
124 0.0, 1.0, 0.0, 0,
125 0.0, 0.0, 1.0, 0,
126 0, 0, 0, 1);
127
128 // error spread for deuteranopia
129 const mat4 errd( 1.0, 0.0, 0.0, 0,
130 0.7, 1.0, 0.7, 0,
131 0.0, 0.0, 1.0, 0,
132 0, 0, 0, 1);
133
134 // error spread for tritanopia
135 const mat4 errt( 1.0, 0.0, 0.0, 0,
136 0.0, 1.0, 0.0, 0,
137 0.7, 0.7, 1.0, 0,
138 0, 0, 0, 1);
139
140 // And the magic happens here...
141 // We construct the matrix that will perform the whole correction.
142
143 // simulation: type of color blindness to simulate:
144 // set to either lms2lmsp, lms2lmsd, lms2lmst
145 mat4 simulation;
146
147 // correction: type of color blindness correction (should match the simulation above):
148 // set to identity, errp, errd, errt ([0] for simulation only)
149 mat4 correction(0);
150
151 switch (mType) {
152 case ColorBlindnessType::Protanomaly:
153 simulation = lms2lmsp;
154 if (mMode == ColorBlindnessMode::Correction)
155 correction = errp;
156 break;
157 case ColorBlindnessType::Deuteranomaly:
158 simulation = lms2lmsd;
159 if (mMode == ColorBlindnessMode::Correction)
160 correction = errd;
161 break;
162 case ColorBlindnessType::Tritanomaly:
163 simulation = lms2lmst;
164 if (mMode == ColorBlindnessMode::Correction)
165 correction = errt;
166 break;
167 case ColorBlindnessType::None:
168 // We already caught this at the beginning of the method, but the
169 // compiler doesn't know that
170 break;
171 }
172
173 mColorTransform = lms2rgb *
174 (simulation * rgb2lms + correction * (rgb2lms - simulation * rgb2lms));
175 }
176
177 } /* namespace android */
178
179 // TODO(b/129481165): remove the #pragma below and fix conversion issues
180 #pragma clang diagnostic pop // ignored "-Wconversion"
181