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filteredge.cpp

/**********************************************************************************
* Copyright (c) 2003, Christoph Rueegg <opendev@cdrnet.ch> and Matthias Bader     *
* All rights reserved.                                                            *
*                                                                                 *
* Project Website: http://www.cdrnet.net/projects/painter/                        *
*                                                                                 *
* Redistribution and use in source and binary forms, with or without modification,*
* are permitted provided that the following conditions are met:                   *
*                                                                                 *
* 1. Redistributions of source code must retain the above copyright notice,       *
* this list of conditions and the following disclaimer.                           *
*                                                                                 *
* 2. Redistributions in binary form must reproduce the above copyright notice,    *
* this list of conditions and the following disclaimer in the documentation       *
* and/or other materials provided with the distribution.                          *
*                                                                                 *
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"     *
* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE       *
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE      *
* ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE        *
* LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR             *
* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF            *
* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS        *
* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN         *
* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)         *
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF          *
* THE POSSIBILITY OF SUCH DAMAGE.                                                 *
**********************************************************************************/

#include "filteredge.h"
#include <cmath>

EdgeFilter::EdgeFilter() : StatelessTransformationFilter() {}

EdgeFilter::~EdgeFilter() {}

ChannelFilter<unsigned char>* EdgeFilter::EmptyClone()
{
  EdgeFilter *copy = new EdgeFilter();
  copy->SetSubChannel(ChannelFilter<unsigned char>::GetSubChannel());
  return(copy);
}

void EdgeFilter::OnTransform(Channel<unsigned char>* source, Channel<unsigned char>* target, int x0, int y0, int x1, int y1)
{
  int sh = abs(x1-x0) + abs(y1-y0);
  if(sh == 0)
    sh = 1;
  double diff;
  unsigned char current;
  for(int x=0;x<source->GetWidth();x++)
  {
    for(int y=0;y<source->GetHeight();y++)
    {
      diff=0;
      current = source->Get(x,y);
      if(x>=sh)
      {
        diff += abs(source->Get(x-sh,y)-current);
      }
      if(x<source->GetWidth()-sh)
      {
        diff += abs(source->Get(x+sh,y)-current);
      }
      if(y>=sh)
      {
        diff += abs(source->Get(x,y-sh)-current);
      }
      if(y<source->GetHeight()-sh)
      {
        diff += abs(source->Get(x,y+sh)-current);
      }
      diff /= 256;
      diff = tanh(diff); // diff=[0..4[
      diff *= 255;
      target->Set(x,y,(unsigned char)diff);
    }
  }
}

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