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
setLevel(int32_t level)40 void Daltonizer::setLevel(int32_t level) {
41 if (level < 0 || level > 10) {
42 return;
43 }
44
45 float newLevel = level / 10.0f;
46 if (std::fabs(mLevel - newLevel) > 0.09f) {
47 mDirty = true;
48 }
49 mLevel = newLevel;
50 }
51
operator ()()52 const mat4& Daltonizer::operator()() {
53 if (mDirty) {
54 mDirty = false;
55 update();
56 }
57 return mColorTransform;
58 }
59
update()60 void Daltonizer::update() {
61 if (mType == ColorBlindnessType::None) {
62 mColorTransform = mat4();
63 return;
64 }
65
66 // converts a linear RGB color to the XYZ space
67 const mat4 rgb2xyz( 0.4124, 0.2126, 0.0193, 0,
68 0.3576, 0.7152, 0.1192, 0,
69 0.1805, 0.0722, 0.9505, 0,
70 0 , 0 , 0 , 1);
71
72 // converts a XYZ color to the LMS space.
73 const mat4 xyz2lms( 0.7328,-0.7036, 0.0030, 0,
74 0.4296, 1.6975, 0.0136, 0,
75 -0.1624, 0.0061, 0.9834, 0,
76 0 , 0 , 0 , 1);
77
78 // Direct conversion from linear RGB to LMS
79 const mat4 rgb2lms(xyz2lms*rgb2xyz);
80
81 // And back from LMS to linear RGB
82 const mat4 lms2rgb(inverse(rgb2lms));
83
84 // To simulate color blindness we need to "remove" the data lost by the absence of
85 // a cone. This cannot be done by just zeroing out the corresponding LMS component
86 // because it would create a color outside of the RGB gammut.
87 // Instead we project the color along the axis of the missing component onto a plane
88 // within the RGB gammut:
89 // - since the projection happens along the axis of the missing component, a
90 // color blind viewer perceives the projected color the same.
91 // - We use the plane defined by 3 points in LMS space: black, white and
92 // blue and red for protanopia/deuteranopia and tritanopia respectively.
93
94 // LMS space red
95 const vec3& lms_r(rgb2lms[0].rgb);
96 // LMS space blue
97 const vec3& lms_b(rgb2lms[2].rgb);
98 // LMS space white
99 const vec3 lms_w((rgb2lms * vec4(1)).rgb);
100
101 // To find the planes we solve the a*L + b*M + c*S = 0 equation for the LMS values
102 // of the three known points. This equation is trivially solved, and has for
103 // solution the following cross-products:
104 const vec3 p0 = cross(lms_w, lms_b); // protanopia/deuteranopia
105 const vec3 p1 = cross(lms_w, lms_r); // tritanopia
106
107 // The following 3 matrices perform the projection of a LMS color onto the given plane
108 // along the selected axis
109
110 // projection for protanopia (L = 0)
111 const mat4 lms2lmsp( 0.0000, 0.0000, 0.0000, 0,
112 -p0.y / p0.x, 1.0000, 0.0000, 0,
113 -p0.z / p0.x, 0.0000, 1.0000, 0,
114 0 , 0 , 0 , 1);
115
116 // projection for deuteranopia (M = 0)
117 const mat4 lms2lmsd( 1.0000, -p0.x / p0.y, 0.0000, 0,
118 0.0000, 0.0000, 0.0000, 0,
119 0.0000, -p0.z / p0.y, 1.0000, 0,
120 0 , 0 , 0 , 1);
121
122 // projection for tritanopia (S = 0)
123 const mat4 lms2lmst( 1.0000, 0.0000, -p1.x / p1.z, 0,
124 0.0000, 1.0000, -p1.y / p1.z, 0,
125 0.0000, 0.0000, 0.0000, 0,
126 0 , 0 , 0 , 1);
127
128 // We will calculate the error between the color and the color viewed by
129 // a color blind user and "spread" this error onto the healthy cones.
130 // The matrices below perform this last step and have been chosen arbitrarily.
131
132 // Scale 0 represents no change (mColorTransform is identical matrix).
133 // error spread for protanopia
134 const mat4 errp(1.0, mLevel, mLevel, 0.0,
135 0.0, 1.0, 0.0, 0.0,
136 0.0, 0.0, 1.0, 0.0,
137 0.0, 0.0, 0.0, 1.0);
138
139 // error spread for deuteranopia
140 const mat4 errd( 1.0, 0.0, 0.0, 0.0,
141 mLevel, 1.0, mLevel, 0.0,
142 0.0, 0.0, 1.0, 0.0,
143 0.0, 0.0, 0.0, 1.0);
144
145 // error spread for tritanopia
146 const mat4 errt( 1.0, 0.0, 0.0, 0.0,
147 0.0, 1.0, 0.0, 0.0,
148 mLevel, mLevel, 1.0, 0.0,
149 0.0, 0.0, 0.0, 1.0);
150
151 // And the magic happens here...
152 // We construct the matrix that will perform the whole correction.
153
154 // simulation: type of color blindness to simulate:
155 // set to either lms2lmsp, lms2lmsd, lms2lmst
156 mat4 simulation;
157
158 // correction: type of color blindness correction (should match the simulation above):
159 // set to identity, errp, errd, errt ([0] for simulation only)
160 mat4 correction(0);
161
162 switch (mType) {
163 case ColorBlindnessType::Protanomaly:
164 simulation = lms2lmsp;
165 if (mMode == ColorBlindnessMode::Correction)
166 correction = errp;
167 break;
168 case ColorBlindnessType::Deuteranomaly:
169 simulation = lms2lmsd;
170 if (mMode == ColorBlindnessMode::Correction)
171 correction = errd;
172 break;
173 case ColorBlindnessType::Tritanomaly:
174 simulation = lms2lmst;
175 if (mMode == ColorBlindnessMode::Correction)
176 correction = errt;
177 break;
178 case ColorBlindnessType::None:
179 // We already caught this at the beginning of the method, but the
180 // compiler doesn't know that
181 break;
182 }
183
184 mColorTransform = lms2rgb *
185 (simulation * rgb2lms + correction * (rgb2lms - simulation * rgb2lms));
186 }
187
188 } /* namespace android */
189
190 // TODO(b/129481165): remove the #pragma below and fix conversion issues
191 #pragma clang diagnostic pop // ignored "-Wconversion"
192