47 lines
1.2 KiB
C++
47 lines
1.2 KiB
C++
/* This file is part of Mapnik (c++ mapping toolkit)
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* Copyright (C) 2005 Artem Pavlenko
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*
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* Mapnik is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version 2
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* of the License, or any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
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*/
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//$Id$
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#ifndef GAMMA_HH
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#define GAMMA_HH
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namespace mapnik
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{
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struct gamma
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{
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unsigned char g2l[256];
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unsigned char l2g[256];
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gamma(double gamma=2.0)
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{
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int result;
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for (int i=0;i< 256;i++)
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{
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result=(int)(pow(i/255.0,gamma) * 255.0 + 0.5);
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g2l[i]=(unsigned short)result;
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}
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for (int i = 0; i < 256; i++)
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{
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result = (int)(pow(i/255.0, 1/gamma) * 255.0 + 0.5);
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l2g[i] = (unsigned char)result;
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}
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}
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};
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}
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#endif //GAMMA_HH
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