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/*************************************************************************
* Copyright (C) 2008 Tavian Barnes <tavianator@gmail.com> *
* *
* This file is part of The Dimension Library. *
* *
* The Dimension Library 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. *
* *
* The Dimension Library 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 *
* <http://www.gnu.org/licenses/>. *
*************************************************************************/
/*
* Types to represent color.
*/
#ifndef DIMENSION_COLOR_H
#define DIMENSION_COLOR_H
/* Internally, we use CIE 1931 XYZ color. */
typedef struct {
double filter, trans; /* Filter transparancy only lets light of this color
through; regular transparancy lets all colors
through. filter + trans should be <= 1.0. */
double X, Y, Z;
} dmnsn_color;
typedef struct {
double X, Y, Z; /* X, Y, and Z are tristimulus values, unbounded above zero.
Diffuse white is (0.9505, 1, 1.089). */
} dmnsn_CIE_XYZ;
typedef struct {
double x, y, Y; /* x and y are chromaticity coordinates, and Y is luminance,
in the CIE 1931 xyZ color space. We use an unlimited light
model, so x,y in [0, 1] and Y >= 0, with 1 = diffuse
white */
} dmnsn_CIE_xyY;
typedef struct {
double L, a, b; /* L is luminence (100 = diffuse white); a and b are color-
opponent dimensions. This color space is used for color
arithmetic. */
} dmnsn_CIE_Lab;
typedef struct {
double L, u, v; /* L is luminence (100 = diffuse white); u and v are
chromaticity coordinates. */
} dmnsn_CIE_Luv;
typedef struct {
double R, G, B; /* sRGB R, G, and B values */
} dmnsn_sRGB;
/* Standard whitepoint, determined by the conversion of sRGB white to CIE XYZ */
extern const dmnsn_CIE_XYZ dmnsn_whitepoint;
/* Color conversions */
dmnsn_color dmnsn_color_from_XYZ(dmnsn_CIE_XYZ XYZ);
dmnsn_color dmnsn_color_from_xyY(dmnsn_CIE_xyY xyY);
dmnsn_color dmnsn_color_from_Lab(dmnsn_CIE_Lab Lab, dmnsn_CIE_XYZ white);
dmnsn_color dmnsn_color_from_Luv(dmnsn_CIE_Luv Luv, dmnsn_CIE_XYZ white);
dmnsn_color dmnsn_color_from_sRGB(dmnsn_sRGB sRGB);
dmnsn_CIE_XYZ dmnsn_XYZ_from_color(dmnsn_color color);
dmnsn_CIE_xyY dmnsn_xyY_from_color(dmnsn_color color);
dmnsn_CIE_Lab dmnsn_Lab_from_color(dmnsn_color color, dmnsn_CIE_XYZ white);
dmnsn_CIE_Luv dmnsn_Luv_from_color(dmnsn_color color, dmnsn_CIE_XYZ white);
dmnsn_sRGB dmnsn_sRGB_from_color(dmnsn_color color);
/* Perceptually correct color combination */
dmnsn_color dmnsn_color_add(dmnsn_color color1, dmnsn_color color2);
/* Perceptual color difference */
double dmnsn_color_difference(dmnsn_color color1, dmnsn_color color2);
#endif /* DIMENSION_COLOR_H */
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