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Diffstat (limited to 'src/libclut.c')
| -rw-r--r-- | src/libclut.c | 258 |
1 files changed, 258 insertions, 0 deletions
diff --git a/src/libclut.c b/src/libclut.c new file mode 100644 index 0000000..dc9294c --- /dev/null +++ b/src/libclut.c @@ -0,0 +1,258 @@ +/** + * Copyright © 2016 Mattias Andrée <maandree@member.fsf.org> + * + * 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 <http://www.gnu.org/licenses/>. + */ +#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; +} + |