Which kind of edge function algorithm

[cherry]

I would like to know that which kind of edge algorithms (-edge function) in ImageMajick
If anyone know, Plz suggest me in urgent.

Thanks

[fmw42]

I believe it is a convolution that is equivalent to subtracting a gaussian blur from the original image.

Code: Select all

MagickExport Image *EdgeImage(const Image *image,const double radius,
  ExceptionInfo *exception)
{
  Image
    *edge_image;

  double
    *kernel;

  register long
    i;

  unsigned long
    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 < (long) (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);
}

[anthony]

You can alos use -morphology EdgeIn Diamond
See http://www.imagemagick.org/Usage/morphology/#edge-in

[fmw42]

other edge functions are in my scripts, laplacian, gradient and derivative and dog. see link below