color.c

/*
	DDS GIMP plugin

	Copyright (C) 2004-2012 Shawn Kirst <skirst@gmail.com>,
   with parts (C) 2003 Arne Reuter <homepage@arnereuter.de> where specified.

	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 2 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; see the file COPYING.  If not, write to
	the Free Software Foundation, 51 Franklin Street, Fifth Floor
	Boston, MA 02110-1301, USA.
*/

#include <math.h>

int linear_to_sRGB(int c)
{
   float v = (float)c / 255.0f;
   
   if(v < 0)
      v = 0;
   else if(v > 1)
      v = 1;
   else if(v <= 0.0031308f)
      v = 12.92f * v;
   else
      v = 1.055f * powf(v, 0.41666f) - 0.055f;
   
   return((int)floorf(255.0f * v + 0.5f));
}

int sRGB_to_linear(int c)
{
   float v = (float)c / 255.0f;
   
   if(v < 0)
      v = 0;
   else if(v > 1)
      v = 1;
   else if(v <= 0.04045f)
      v /= 12.92f;
   else
      v = powf((v + 0.055f) / 1.055f, 2.4f);
   
   return((int)floorf(255.0f * v + 0.5f));
}