canny_tool.h

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//
// canny stuff. rewritten, though based on tina
// stumeikle Sat May  4 19:22:36 2002
//
//
//




#ifndef FILTER_CANNY_H
#define FILTER_CANNY_H

#include <cmath>
#include "filter.h"
#include "gauss.h"
#include "image.h"
#include "image_op.h"
#include "property_image.h"
#include "edge_string.h"
#include "edge_string_op.h"

namespace mimas {
  
template<typename T>
class canny_tool
{
    private:
  double  sigma;
  double  precision;
  double  low_edge_thres;
  double  up_edge_thres;
  int len_thres;

    //operator. operates on images
    public:

    canny_tool(void)    
    {
  sigma = 1.0;
  precision = 0.01;
  low_edge_thres = 3.0;
  up_edge_thres = 5.0;
  len_thres = 5;
    }
    edge_string_ptr_list findEdgeStrings( const image<T> &input ) 
    {
      image<int>
        // Compute horizontal and vertical gradients.
        grad_x( gaussGradientX< float >( input, sigma ) ),
        grad_y( gaussGradientY< float >( input, sigma ) ),
  // Create grad sq. The following would be very elegant, but more memory
        // intensive:
  // gradsq = (grad_x*grad_x) + (grad_y*grad_y);
  // (... so we wont ...)
        gradsq( sumSquares( grad_x, grad_y ) );

  // Do non maxima suppression
  // (errr.. shouldnt we look for zero crossings of grad^2 im?)
  edge_image edge_im;
  filter<int>::nonMaximaSuppression( grad_x, grad_y, gradsq,
                                           40.0, edge_im );
  grad_x.clear();
  grad_y.clear();
  gradsq.clear();

  //(5.0) post process the resulting edgels
  // what's the best way to do this ? we could create an edge_image function
  // but it would be better *not* to have specific edge images. better to have image properties
  // than specific image types. anyway image<int> is a perfectly valid edge image too.
  edge_string_ptr_list edge_strings;
  edge_string_op  eop;

  edge_strings = eop.extractFromImage( edge_im, 5, 5.0 );

  //done canny ----------------------------------------------------
  return edge_strings;
    }
};

};

#endif

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