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/* LIBGIMP - The GIMP Library
* Copyright (C) 1995-1997 Peter Mattis and Spencer Kimball
*
* This 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.
*
* This 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
* Library General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library. If not, see
* <https://www.gnu.org/licenses/>.
*/
#ifndef __GIMP_COLOR_PRIVATE_H__
#define __GIMP_COLOR_PRIVATE_H__
/* Legacy definition to calculate luminance from sRGB.
*
* These values and macro are specific to a "RGB float" to "Y float"
* conversion within sRGB space. These should not be used in new code,
* where converting to "Y float", space aware, may often be what you
* wanted to do.
* Once we got rid of all remaining usages in plug-ins and app, we can
* delete this file as it's not distributed.
*/
#define GIMP_RGB_LUMINANCE_RED (0.22248840)
#define GIMP_RGB_LUMINANCE_GREEN (0.71690369)
#define GIMP_RGB_LUMINANCE_BLUE (0.06060791)
#define GIMP_RGB_LUMINANCE(r,g,b) ((r) * GIMP_RGB_LUMINANCE_RED + \
(g) * GIMP_RGB_LUMINANCE_GREEN + \
(b) * GIMP_RGB_LUMINANCE_BLUE)
#endif /* __GIMP_COLOR_PRIVATE_H__ */
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