53 lines
1.7 KiB
C++
53 lines
1.7 KiB
C++
/*****************************************************************************
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*
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* This file is part of Mapnik (c++ mapping toolkit)
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*
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* Copyright (C) 2006 Artem Pavlenko
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*
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* This library is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation; either
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* version 2.1 of the License, or (at your option) any later version.
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*
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* This library 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 GNU
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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with this library; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
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*
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*****************************************************************************/
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//$Id: gamma.hpp 39 2005-04-10 20:39:53Z pavlenko $
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#ifndef GAMMA_HPP
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#define GAMMA_HPP
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#include <cmath>
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namespace mapnik
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{
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struct MAPNIK_DECL 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)(std::pow(i/255.0,gamma) * 255.0 + 0.5);
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g2l[i]=(unsigned char)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)(std::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_HPP
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