utils.ColorUtils Maven / Gradle / Ivy
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/*
* Copyright 2021 Google LLC
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
// This file is automatically generated. Do not modify it.
package utils;
/**
* Color science utilities.
*
* Utility methods for color science constants and color space conversions that aren't HCT or
* CAM16.
*/
public class ColorUtils {
private ColorUtils() {}
static final double[][] SRGB_TO_XYZ =
new double[][] {
new double[] {0.41233895, 0.35762064, 0.18051042},
new double[] {0.2126, 0.7152, 0.0722},
new double[] {0.01932141, 0.11916382, 0.95034478},
};
static final double[][] XYZ_TO_SRGB =
new double[][] {
new double[] {
3.2413774792388685, -1.5376652402851851, -0.49885366846268053,
},
new double[] {
-0.9691452513005321, 1.8758853451067872, 0.04156585616912061,
},
new double[] {
0.05562093689691305, -0.20395524564742123, 1.0571799111220335,
},
};
static final double[] WHITE_POINT_D65 = new double[] {95.047, 100.0, 108.883};
/** Converts a color from RGB components to ARGB format. */
public static int argbFromRgb(int red, int green, int blue) {
return (255 << 24) | ((red & 255) << 16) | ((green & 255) << 8) | (blue & 255);
}
/** Converts a color from linear RGB components to ARGB format. */
public static int argbFromLinrgb(double[] linrgb) {
int r = delinearized(linrgb[0]);
int g = delinearized(linrgb[1]);
int b = delinearized(linrgb[2]);
return argbFromRgb(r, g, b);
}
/** Returns the alpha component of a color in ARGB format. */
public static int alphaFromArgb(int argb) {
return (argb >> 24) & 255;
}
/** Returns the red component of a color in ARGB format. */
public static int redFromArgb(int argb) {
return (argb >> 16) & 255;
}
/** Returns the green component of a color in ARGB format. */
public static int greenFromArgb(int argb) {
return (argb >> 8) & 255;
}
/** Returns the blue component of a color in ARGB format. */
public static int blueFromArgb(int argb) {
return argb & 255;
}
/** Returns whether a color in ARGB format is opaque. */
public static boolean isOpaque(int argb) {
return alphaFromArgb(argb) >= 255;
}
/** Converts a color from ARGB to XYZ. */
public static int argbFromXyz(double x, double y, double z) {
double[][] matrix = XYZ_TO_SRGB;
double linearR = matrix[0][0] * x + matrix[0][1] * y + matrix[0][2] * z;
double linearG = matrix[1][0] * x + matrix[1][1] * y + matrix[1][2] * z;
double linearB = matrix[2][0] * x + matrix[2][1] * y + matrix[2][2] * z;
int r = delinearized(linearR);
int g = delinearized(linearG);
int b = delinearized(linearB);
return argbFromRgb(r, g, b);
}
/** Converts a color from XYZ to ARGB. */
public static double[] xyzFromArgb(int argb) {
double r = linearized(redFromArgb(argb));
double g = linearized(greenFromArgb(argb));
double b = linearized(blueFromArgb(argb));
return MathUtils.matrixMultiply(new double[] {r, g, b}, SRGB_TO_XYZ);
}
/** Converts a color represented in Lab color space into an ARGB integer. */
public static int argbFromLab(double l, double a, double b) {
double[] whitePoint = WHITE_POINT_D65;
double fy = (l + 16.0) / 116.0;
double fx = a / 500.0 + fy;
double fz = fy - b / 200.0;
double xNormalized = labInvf(fx);
double yNormalized = labInvf(fy);
double zNormalized = labInvf(fz);
double x = xNormalized * whitePoint[0];
double y = yNormalized * whitePoint[1];
double z = zNormalized * whitePoint[2];
return argbFromXyz(x, y, z);
}
/**
* Converts a color from ARGB representation to L*a*b* representation.
*
* @param argb the ARGB representation of a color
* @return a Lab object representing the color
*/
public static double[] labFromArgb(int argb) {
double linearR = linearized(redFromArgb(argb));
double linearG = linearized(greenFromArgb(argb));
double linearB = linearized(blueFromArgb(argb));
double[][] matrix = SRGB_TO_XYZ;
double x = matrix[0][0] * linearR + matrix[0][1] * linearG + matrix[0][2] * linearB;
double y = matrix[1][0] * linearR + matrix[1][1] * linearG + matrix[1][2] * linearB;
double z = matrix[2][0] * linearR + matrix[2][1] * linearG + matrix[2][2] * linearB;
double[] whitePoint = WHITE_POINT_D65;
double xNormalized = x / whitePoint[0];
double yNormalized = y / whitePoint[1];
double zNormalized = z / whitePoint[2];
double fx = labF(xNormalized);
double fy = labF(yNormalized);
double fz = labF(zNormalized);
double l = 116.0 * fy - 16;
double a = 500.0 * (fx - fy);
double b = 200.0 * (fy - fz);
return new double[] {l, a, b};
}
/**
* Converts an L* value to an ARGB representation.
*
* @param lstar L* in L*a*b*
* @return ARGB representation of grayscale color with lightness matching L*
*/
public static int argbFromLstar(double lstar) {
double y = yFromLstar(lstar);
int component = delinearized(y);
return argbFromRgb(component, component, component);
}
/**
* Computes the L* value of a color in ARGB representation.
*
* @param argb ARGB representation of a color
* @return L*, from L*a*b*, coordinate of the color
*/
public static double lstarFromArgb(int argb) {
double y = xyzFromArgb(argb)[1];
return 116.0 * labF(y / 100.0) - 16.0;
}
/**
* Converts an L* value to a Y value.
*
*
L* in L*a*b* and Y in XYZ measure the same quantity, luminance.
*
*
L* measures perceptual luminance, a linear scale. Y in XYZ measures relative luminance, a
* logarithmic scale.
*
* @param lstar L* in L*a*b*
* @return Y in XYZ
*/
public static double yFromLstar(double lstar) {
return 100.0 * labInvf((lstar + 16.0) / 116.0);
}
/**
* Converts a Y value to an L* value.
*
*
L* in L*a*b* and Y in XYZ measure the same quantity, luminance.
*
*
L* measures perceptual luminance, a linear scale. Y in XYZ measures relative luminance, a
* logarithmic scale.
*
* @param y Y in XYZ
* @return L* in L*a*b*
*/
public static double lstarFromY(double y) {
return labF(y / 100.0) * 116.0 - 16.0;
}
/**
* Linearizes an RGB component.
*
* @param rgbComponent 0 <= rgb_component <= 255, represents R/G/B channel
* @return 0.0 <= output <= 100.0, color channel converted to linear RGB space
*/
public static double linearized(int rgbComponent) {
double normalized = rgbComponent / 255.0;
if (normalized <= 0.040449936) {
return normalized / 12.92 * 100.0;
} else {
return Math.pow((normalized + 0.055) / 1.055, 2.4) * 100.0;
}
}
/**
* Delinearizes an RGB component.
*
* @param rgbComponent 0.0 <= rgb_component <= 100.0, represents linear R/G/B channel
* @return 0 <= output <= 255, color channel converted to regular RGB space
*/
public static int delinearized(double rgbComponent) {
double normalized = rgbComponent / 100.0;
double delinearized = 0.0;
if (normalized <= 0.0031308) {
delinearized = normalized * 12.92;
} else {
delinearized = 1.055 * Math.pow(normalized, 1.0 / 2.4) - 0.055;
}
return MathUtils.clampInt(0, 255, (int) Math.round(delinearized * 255.0));
}
/**
* Returns the standard white point; white on a sunny day.
*
* @return The white point
*/
public static double[] whitePointD65() {
return WHITE_POINT_D65;
}
static double labF(double t) {
double e = 216.0 / 24389.0;
double kappa = 24389.0 / 27.0;
if (t > e) {
return Math.pow(t, 1.0 / 3.0);
} else {
return (kappa * t + 16) / 116;
}
}
static double labInvf(double ft) {
double e = 216.0 / 24389.0;
double kappa = 24389.0 / 27.0;
double ft3 = ft * ft * ft;
if (ft3 > e) {
return ft3;
} else {
return (116 * ft - 16) / kappa;
}
}
}