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/*
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%     E d g e I m a g e                                                       %
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%
%  EdgeImage() finds edges in an image.  Radius defines the radius of the
%  convolution filter.  Use a radius of 0 and EdgeImage() selects a suitable
%  radius for you.
%
%  The format of the EdgeImage method is:
%
%      Image *EdgeImage(const Image *image,const double radius,
%        ExceptionInfo *exception)
%
%  A description of each parameter follows:
%
%    o image: the image.
%
%    o radius: the radius of the pixel neighborhood.
%
%    o exception: return any errors or warnings in this structure.
%
*/
MagickExport Image *EdgeImage(const Image *image,const double radius,
  ExceptionInfo *exception)
{
  Image
    *edge_image;

  double
    *kernel;

  register ssize_t
    i;

  size_t
    width;

  assert(image != (const Image *) NULL);
  assert(image->signature == MagickSignature);
  if (image->debug != MagickFalse)
    (void) LogMagickEvent(TraceEvent,GetMagickModule(),"%s",image->filename);
  assert(exception != (ExceptionInfo *) NULL);
  assert(exception->signature == MagickSignature);
  width=GetOptimalKernelWidth1D(radius,0.5);
  kernel=(double *) AcquireQuantumMemory((size_t) width,width*sizeof(*kernel));
  if (kernel == (double *) NULL)
    ThrowImageException(ResourceLimitError,"MemoryAllocationFailed");
  for (i=0; i < (ssize_t) (width*width); i++)
    kernel[i]=(-1.0);
  kernel[i/2]=(double) (width*width-1.0);
  edge_image=ConvolveImage(image,width,kernel,exception);
  kernel=(double *) RelinquishMagickMemory(kernel);
  return(edge_image);
}