177 lines
6.0 KiB
C++
177 lines
6.0 KiB
C++
/*
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* Copyright 2013 The Android Open Source Project
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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#include "Daltonizer.h"
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#include <ui/mat4.h>
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namespace android {
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Daltonizer::Daltonizer() :
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mType(deuteranomaly), mMode(simulation), mDirty(true) {
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}
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Daltonizer::~Daltonizer() {
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}
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void Daltonizer::setType(Daltonizer::ColorBlindnessTypes type) {
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if (type != mType) {
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mDirty = true;
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mType = type;
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}
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}
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void Daltonizer::setMode(Daltonizer::Mode mode) {
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if (mode != mMode) {
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mDirty = true;
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mMode = mode;
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}
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}
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const mat4& Daltonizer::operator()() {
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if (mDirty) {
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mDirty = false;
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update();
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}
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return mColorTransform;
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}
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void Daltonizer::update() {
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// converts a linear RGB color to the XYZ space
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const mat4 rgb2xyz( 0.4124, 0.2126, 0.0193, 0,
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0.3576, 0.7152, 0.1192, 0,
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0.1805, 0.0722, 0.9505, 0,
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0 , 0 , 0 , 1);
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// converts a XYZ color to the LMS space.
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const mat4 xyz2lms( 0.7328,-0.7036, 0.0030, 0,
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0.4296, 1.6975, 0.0136, 0,
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-0.1624, 0.0061, 0.9834, 0,
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0 , 0 , 0 , 1);
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// Direct conversion from linear RGB to LMS
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const mat4 rgb2lms(xyz2lms*rgb2xyz);
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// And back from LMS to linear RGB
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const mat4 lms2rgb(inverse(rgb2lms));
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// To simulate color blindness we need to "remove" the data lost by the absence of
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// a cone. This cannot be done by just zeroing out the corresponding LMS component
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// because it would create a color outside of the RGB gammut.
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// Instead we project the color along the axis of the missing component onto a plane
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// within the RGB gammut:
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// - since the projection happens along the axis of the missing component, a
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// color blind viewer perceives the projected color the same.
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// - We use the plane defined by 3 points in LMS space: black, white and
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// blue and red for protanopia/deuteranopia and tritanopia respectively.
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// LMS space red
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const vec3& lms_r(rgb2lms[0].rgb);
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// LMS space blue
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const vec3& lms_b(rgb2lms[2].rgb);
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// LMS space white
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const vec3 lms_w((rgb2lms * vec4(1)).rgb);
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// To find the planes we solve the a*L + b*M + c*S = 0 equation for the LMS values
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// of the three known points. This equation is trivially solved, and has for
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// solution the following cross-products:
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const vec3 p0 = cross(lms_w, lms_b); // protanopia/deuteranopia
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const vec3 p1 = cross(lms_w, lms_r); // tritanopia
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// The following 3 matrices perform the projection of a LMS color onto the given plane
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// along the selected axis
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// projection for protanopia (L = 0)
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const mat4 lms2lmsp( 0.0000, 0.0000, 0.0000, 0,
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-p0.y / p0.x, 1.0000, 0.0000, 0,
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-p0.z / p0.x, 0.0000, 1.0000, 0,
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0 , 0 , 0 , 1);
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// projection for deuteranopia (M = 0)
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const mat4 lms2lmsd( 1.0000, -p0.x / p0.y, 0.0000, 0,
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0.0000, 0.0000, 0.0000, 0,
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0.0000, -p0.z / p0.y, 1.0000, 0,
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0 , 0 , 0 , 1);
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// projection for tritanopia (S = 0)
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const mat4 lms2lmst( 1.0000, 0.0000, -p1.x / p1.z, 0,
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0.0000, 1.0000, -p1.y / p1.z, 0,
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0.0000, 0.0000, 0.0000, 0,
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0 , 0 , 0 , 1);
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// We will calculate the error between the color and the color viewed by
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// a color blind user and "spread" this error onto the healthy cones.
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// The matrices below perform this last step and have been chosen arbitrarily.
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// The amount of correction can be adjusted here.
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// error spread for protanopia
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const mat4 errp( 1.0, 0.7, 0.7, 0,
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0.0, 1.0, 0.0, 0,
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0.0, 0.0, 1.0, 0,
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0, 0, 0, 1);
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// error spread for deuteranopia
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const mat4 errd( 1.0, 0.0, 0.0, 0,
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0.7, 1.0, 0.7, 0,
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0.0, 0.0, 1.0, 0,
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0, 0, 0, 1);
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// error spread for tritanopia
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const mat4 errt( 1.0, 0.0, 0.0, 0,
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0.0, 1.0, 0.0, 0,
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0.7, 0.7, 1.0, 0,
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0, 0, 0, 1);
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const mat4 identity;
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// And the magic happens here...
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// We construct the matrix that will perform the whole correction.
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// simulation: type of color blindness to simulate:
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// set to either lms2lmsp, lms2lmsd, lms2lmst
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mat4 simulation;
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// correction: type of color blindness correction (should match the simulation above):
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// set to identity, errp, errd, errt ([0] for simulation only)
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mat4 correction(0);
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switch (mType) {
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case protanopia:
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case protanomaly:
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simulation = lms2lmsp;
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if (mMode == Daltonizer::correction)
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correction = errp;
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break;
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case deuteranopia:
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case deuteranomaly:
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simulation = lms2lmsd;
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if (mMode == Daltonizer::correction)
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correction = errd;
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break;
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case tritanopia:
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case tritanomaly:
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simulation = lms2lmst;
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if (mMode == Daltonizer::correction)
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correction = errt;
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break;
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}
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mColorTransform = lms2rgb *
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(simulation * rgb2lms + correction * (rgb2lms - simulation * rgb2lms));
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}
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} /* namespace android */
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