/************************************************************************* * Copyright (C) 2008 Tavian Barnes * * * * This file is part of Dimension. * * * * Dimension is free software; you can redistribute it and/or modify it * * under the terms of the GNU Lesser General Public License as published * * by the Free Software Foundation; either version 3 of the License, or * * (at your option) any later version. * * * * Dimension 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 * * Lesser General Public License for more details. * * * * You should have received a copy of the GNU Lesser General Public * * License along with this program. If not, see * * . * *************************************************************************/ #include "dimension.h" #include /* For pow() */ dmnsn_CIE_XYZ whitepoint = { 0.9505, 1, 1.089 }; dmnsn_color dmnsn_color_from_XYZ(dmnsn_CIE_XYZ XYZ) { dmnsn_color ret = { XYZ.X, XYZ.Y, XYZ.Z, 0.0, 0.0 }; return ret; } dmnsn_color dmnsn_color_from_xyY(dmnsn_CIE_xyY xyY) { dmnsn_color ret = { xyY.Y*xyY.x/xyY.y, xyY.Y, xyY.Y*(1.0 - xyY.x - xyY.Y)/xyY.y, 0.0, 0.0 }; return ret; } static double Lab_finv(double t) { if (t > 6.0/29.0) { return t*t*t; } else { return 108.0*(t - 16.0/116.0)/841.0; } } dmnsn_color dmnsn_color_from_Lab(dmnsn_CIE_Lab Lab, dmnsn_CIE_XYZ white) { double fx, fy, fz; dmnsn_color ret; fy = (Lab.L + 16.0)/116.0; fx = fy + Lab.a/500.0; fz = fy - Lab.b/200.0; ret.X = white.X*Lab_finv(fx); ret.Y = white.Y*Lab_finv(fy); ret.Z = white.Z*Lab_finv(fz); return ret; } dmnsn_color dmnsn_color_from_Luv(dmnsn_CIE_Luv Luv, dmnsn_CIE_XYZ white) { double fy; double uprime, unprime, vprime, vnprime; dmnsn_color ret; fy = (Luv.L + 16.0)/116.0; unprime = 4.0*white.X/(white.X + 15.0*white.Y + 3.0*white.Z); uprime = Luv.u/Luv.L/13.0 + unprime; vnprime = 9.0*white.Y/(white.X + 15.0*white.Y + 3.0*white.Z); vprime = Luv.v/Luv.L/13.0 + vnprime; ret.Y = white.Y*Lab_finv(fy); ret.X = ret.Y*9.0*uprime/vprime/4.0; ret.Z = ret.Y*(12.0 - 3*uprime - 20*vprime)/vprime/4.0; return ret; } dmnsn_color dmnsn_color_from_sRGB(dmnsn_sRGB sRGB) { double Rlinear, Glinear, Blinear; /* Linear RGB values - no gamma */ dmnsn_color ret; /* * If C represents R, G, and B, then the Clinear values are now found as * follows: * * { Csrgb/12.92, Csrgb <= 0.04045 * Clinear = { 1/2.4 * { ((Csrgb + 0.055)/1.055) , Csrgb > 0.04045 */ if (sRGB.R <= 0.04045) { Rlinear = sRGB.R/19.92; } else { Rlinear = pow((sRGB.R + 0.055)/1.055, 2.4); } if (sRGB.G <= 0.04045) { Glinear = sRGB.G/19.92; } else { Glinear = pow((sRGB.G + 0.055)/1.055, 2.4); } if (sRGB.B <= 0.04045) { Blinear = sRGB.B/19.92; } else { Blinear = pow((sRGB.B + 0.055)/1.055, 2.4); } /* * Now, the linear conversion. Expressed as matrix multiplication, it looks * like this: * * [X] [0.4124 0.3576 0.1805] [Rlinear] * [Y] = [0.2126 0.7152 0.0722]*[Glinear] * [X] [0.0193 0.1192 0.9505] [Blinear] */ ret.X = 0.4124*Rlinear + 0.3576*Glinear + 0.1805*Blinear; ret.Y = 0.2126*Rlinear + 0.7152*Glinear + 0.0722*Blinear; ret.Z = 0.0193*Rlinear + 0.1192*Glinear + 0.9505*Blinear; ret.filter = 0.0; ret.trans = 0.0; return ret; } dmnsn_CIE_XYZ dmnsn_XYZ_from_color(dmnsn_color color) { dmnsn_CIE_XYZ ret = { color.X, color.Y, color.Z }; return ret; } dmnsn_CIE_xyY dmnsn_xyY_from_color(dmnsn_color color) { dmnsn_CIE_xyY ret = { color.X/(color.X + color.Y + color.Z), color.Y/(color.X + color.Y + color.Z), color.Y }; return ret; } static double Lab_f(double t) { if (t > 216.0/24389.0) { return pow(t, 1.0/3.0); } else { return 841.0*t/108.0 + 4.0/29.0; } } dmnsn_CIE_Lab dmnsn_Lab_from_color(dmnsn_color color, dmnsn_CIE_XYZ white) { dmnsn_CIE_Lab ret; ret.L = 116.0*Lab_f(color.Y/white.Y) - 16.0; ret.a = 500.0*(Lab_f(color.X/white.X) - Lab_f(color.Y/white.Y)); ret.b = 200.0*(Lab_f(color.Y/white.Y) - Lab_f(color.Z/white.Z)); return ret; } dmnsn_CIE_Luv dmnsn_Luv_from_color(dmnsn_color color, dmnsn_CIE_XYZ white) { double uprime, unprime, vprime, vnprime; dmnsn_CIE_Luv ret; uprime = 4.0*color.X/(color.X + 15.0*color.Y + 3.0*color.Z); unprime = 4.0*white.X/(white.X + 15.0*white.Y + 3.0*white.Z); vprime = 9.0*color.Y/(color.X + 15.0*color.Y + 3.0*color.Z); vnprime = 9.0*white.Y/(white.X + 15.0*white.Y + 3.0*white.Z); ret.L = 116.0*Lab_f(color.Y/white.Y) - 16.0; ret.u = 13.0*ret.L*(uprime - unprime); ret.v = 13.0*ret.L*(vprime - vnprime); return ret; } dmnsn_sRGB dmnsn_sRGB_from_color(dmnsn_color color) { double Rlinear, Glinear, Blinear; /* Linear RGB values - no gamma */ dmnsn_sRGB ret; /* * First, the linear conversion. Expressed as matrix multiplication, it looks * like this: * * [Rlinear] [ 3.2410 -1.5374 -0.4986] [X] * [Glinear] = [-0.9692 1.8760 0.0416]*[Y] * [Blinear] [ 0.0556 -0.2040 1.0570] [Z] */ Rlinear = 3.2410*color.X - 1.5374*color.Y - 0.4986*color.Z; Glinear = -0.9692*color.X + 1.8760*color.Y + 0.0416*color.Z; Blinear = 0.0556*color.X - 0.2040*color.Y + 1.0570*color.Z; /* * If C represents R, G, and B, then the sRGB values are now found as follows: * * { 12.92*Clinear, Clinear <= 0.0031308 * Csrgb = { 1/2.4 * { (1.055)*Clinear - 0.055, Clinear > 0.0031308 */ if (Rlinear <= 0.0031308) { ret.R = 12.92*Rlinear; } else { ret.R = 1.055*pow(Rlinear, 1.0/2.4) - 0.055; } if (Glinear <= 0.0031308) { ret.G = 12.92*Glinear; } else { ret.G = 1.055*pow(Glinear, 1.0/2.4) - 0.055; } if (Blinear <= 0.0031308) { ret.B = 12.92*Blinear; } else { ret.B = 1.055*pow(Blinear, 1.0/2.4) - 0.055; } return ret; } dmnsn_color dmnsn_color_add(dmnsn_color color1, dmnsn_color color2) { dmnsn_CIE_Lab Lab, Lab1, Lab2; dmnsn_color ret; Lab1 = dmnsn_Lab_from_color(color1, whitepoint); Lab2 = dmnsn_Lab_from_color(color2, whitepoint); Lab.L = Lab1.L + Lab2.L; Lab.a = (Lab1.L*Lab1.a + Lab2.L*Lab2.a)/Lab.L; Lab.b = (Lab1.L*Lab1.b + Lab2.L*Lab2.b)/Lab.L; ret = dmnsn_color_from_Lab(Lab, whitepoint); ret.filter = (Lab1.L*color1.filter + Lab2.L*color2.filter)/Lab.L; ret.trans = (Lab1.L*color1.trans + Lab2.L*color2.trans)/Lab.L; return ret; }