/** * Copyright © 2016 Mattias Andrée * * This program is free software: you can redistribute it and/or modify * it under the terms of the GNU General Public License as published by * the Free Software Foundation, either version 3 of the License, or * (at your option) any later version. * * This program is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the * GNU General Public License for more details. * * You should have received a copy of the GNU General Public License * along with this program. If not, see . */ #include "libclut.h" /** * Convert one component from [0, 1] linear RGB to [0, 1] sRGB. * * @param c The linear RGB value. * @return Corresponding sRGB value. */ double libclut_model_linear_to_standard1(double c) { return (c <= 0.0031308) ? (12.92 * c) : ((1.0 + 0.055) * pow(c, 1.0 / 2.4)); } /** * Convert [0, 1] linear RGB to [0, 1] sRGB. * * @param r Pointer to the linear red component, * and output parameter for the red component. * @param g Pointer to the linear green component, * and output parameter for the green component. * @param b Pointer to the linear blue component, * and output parameter for the blue component. */ void libclut_model_linear_to_standard(double* r, double* g, double* b) { *r = libclut_model_linear_to_standard1(*r): *g = libclut_model_linear_to_standard1(*g); *b = libclut_model_linear_to_standard1(*b); } /** * Convert one component from [0, 1] sRGB to [0, 1] linear RGB. * * @param c The sRGB value. * @return Corresponding linear RGB value. */ double libclut_model_standard_to_linear1(double c) { return (c <= 0.04045) ? (c / 12.92) : pow((c + 0.055) / (1.0 + 0.055), 2.4); } /** * Convert [0, 1] sRGB to [0, 1] linear RGB. * * @param r Pointer to the red component, and output * parameter for the linear red component. * @param g Pointer to the green component, and output * parameter for the linear green component. * @param b Pointer to the blue component, and output * parameter for the linear blue component. */ void libclut_model_standard_to_linear(double* r, double* g, double* b) { *r = libclut_model_standard_to_linear1(*r): *g = libclut_model_standard_to_linear1(*g); *b = libclut_model_standard_to_linear1(*b); } /** * Convert CIE xyY to CIE XYZ. * * @param x The x parameter. * @param y The y parameter. * @param Y The Y parameter. This is also the Y (middle) parameter for the CIE XYZ colour. * @param X Output parameter for the X parameter. * @param Z Output parameter for the Z parameter. */ void libclut_model_ciexyy_to_ciexyz(double x, double y, double Y, double* X, double* Z) { *X = (y == 0.0) ? Y : (Y * x / y); *Z = (y == 0.0) ? Y : (Y * (1 - x - y) / y); } /** * Convert CIE XYZ to CIE xyY. * * @param X The X parameter. * @param Y The Y parameter. This is also the Y (last) parameter for the CIE xyY colour. * @param Z The Z parameter. * @param x Output parameter for the x parameter. * @param y Output parameter for the y parameter. */ void libclut_model_ciexyz_to_ciexyy(double X, double Y, double Z, double* x, double* y) { double s = X + Y + Z; if (s == 0.0) *x = *y = 0.0; else *x = X / s, *y = Y / s; } /** * Convert CIE XYZ to [0, 1] linear RGB. * * @param X The X parameter. * @param Y The Y parameter. * @param Z The Z parameter. * @param r Output parameter for the red component. * @param g Output parameter for the green component. * @param b Output parameter for the blue component. */ void libclut_model_ciexyz_to_linear(double X, double Y, double Z, double* r, double* g, double* b) { *r = ( 3.2404500 * X) + (-1.537140 * Y) + (-0.4985320 * Z); *g = (-0.9692660 * X) + ( 1.876010 * Y) + ( 0.0415561 * Z); *b = ( 0.0556434 * X) + (-0.204026 * Y) + ( 1.0572300 * Z); } /** * Convert [0, 1] linear RGB to CIE XYZ. * * @param r The red component. * @param g The green component. * @param b The blue component. * @param X Output parameter for the X parameter. * @param Y Output parameter for the Y parameter. * @param Z Output parameter for the Z parameter. */ void libclut_model_linear_to_ciexyz(double r, double g, double b, double* X, double* Y, double* Z) { *X = (0.4124564 * r) + (0.3575761 * g) + (0.1804375 * b); *Y = (0.2126729 * r) + (0.7151522 * g) + (0.0721750 * b); *Z = (0.0193339 * r) + (0.1191920 * g) + (0.9503041 * b); } /** * Convert [0, 1] linear RGB to CIE xyY. * * @param r The red component. * @param g The green component. * @param b The blue component. * @param x Output parameter for the x parameter. * @param y Output parameter for the y parameter. * @param Y Output parameter for the Y parameter. */ void libclut_model_srgb_to_ciexyy(double r, double g, double b, double* x, double* y, double* Y) { double X, Z; libclut_model_standard_to_linear(&r, &g, &b); libclut_model_linear_to_ciexyz(r, g, b, &X, Y, &Z); libclut_model_ciexyz_to_ciexyy(X, *Y, Z, x, y); } /** * Convert CIE xyY to [0, 1] sRGB. * * @param x The x parameter. * @param y The y parameter. * @param Y The Y parameter. * @param r Output parameter for the red component. * @param g Output parameter for the green component. * @param b Output parameter for the blue component. */ void libclut_model_ciexyy_to_srgb(double x, double y, double Y, double* r, double* g, double* b) { double X, Z; libclut_model_ciexyy_to_ciexyz(x, y, Y, &X, &Z); libclut_model_ciexyz_to_linear(X, *Y, Z, r, g, b); libclut_model_linear_to_standard(r, g, b); } /** * Convert from CIE XYZ to CIE L*a*b*. * * @param X The X parameter. * @param Y The Y parameter. * @param Z The Z parameter. * @param L Output parameter for the L* component. * @param a Output parameter for the a* component. * @param b Output parameter for the b* component. */ void libclut_model_ciexyz_to_cielab(double X, double Y, double Z, double* L, double* a, double* b) { #define F(C) ((C) > 0.00885642) ? pow((C), 1.0 / 3.0) : ((7.78 + 703.0 / 99900.0) * (C) + 0.1379310) X /= 0.95047, Z /= 1.08883; X = F(X), Y = F(Y), Z = F(Z); *L = 116.0 * Y - 16.0; *a = 500.0 * (X - Y); *b = 200.0 * (Y - Z); #undef F } /** * Convert from CIE L*a*b* to CIE XYZ. * * @param L The L* component. * @param a The a component. * @param b The b component. * @param X Output parameter for the X parameter. * @param Y Output parameter for the Y parameter. * @param Z Output parameter for the Z parameter. */ void libclut_model_cielab_to_xiexyz(double L, double a, double b, double* X, double* Y, double* Z) { #define F(C) (((C)*(C)*(C) > 0.00885642) ? ((C)*(C)*(C)) : (((C) - 0.1379310) / (7.78 + 703.0 / 99900.0))) *Y = (l + 16.0) / 116.0; *X = a / 500.0 + *Y; *Z = *Y - b / 200.0; *X = F(*X) * 0.95047; *Y = F(*Y); *Z = F(*Z) * 1.08883; #undef F } /** * Convert the distance (∆E*_ab) between two [0, 1] sRGB colours. * * @param r1 The red component of the first colour. * @param g1 The green component of the first colour. * @param b1 The blue component of the first colour. * @param r2 The red component of the second colour. * @param g2 The green component of the second colour. * @param b2 The blue component of the second colour. * @return The difference. */ double libclut_model_delta_e(double r1, double g1, double b1, double r2, double g2, double b2) { double X1, Y1, Z1, L1, a1, b1, X2, Y2, Z2, L2, a2, b2; standard_to_linear(&r1, &g1, &b1), standard_to_linear(&r2, &g2, &b2); linear_to_ciexyz(r1, g1, b1, &X1, &Y1, &Z1), linear_to_ciexyz(r2, g2, b2, &X2, &Y2, &Z2); ciexyz_to_cielab(X1, Y1, Z1, &L1, &a1, &b1), ciexyz_to_cielab(X2, Y2, Z2, &L2, &a2, &b2); L1 -= L2, L1 *= L1; a1 -= a2, a1 *= a1; b1 -= b2, b1 *= b1; return L1 + a1 + b1; }