src/Tests_hough/test_hough_gradient.m

   1 function test_hough_gradient(images_path, image_name, use_edges_mask)
   2     i = imread([images_path image_name]);
   3
   4     green = i(:,:,2);
   5     green_filtered = imgaussfilt(green, 1.0);
   6
   7     edges = zeros(size(green));
   8     if use_edges_mask
   9         otsu = ~im2bw(green_filtered, graythresh(green_filtered));
  10         se = strel('rectangle', [3 3]);
  11         edges = imdilate(otsu, se) - imerode(otsu, se);
  12     end
  13
  14     s = [-1 0 1; -2 0 2; -1 0 1];
  15     x_edge = conv2(cast(green_filtered, 'double'), s , 'valid');
  16     y_edge = conv2(cast(green_filtered, 'double'), s', 'valid');
  17
  18     magnitudes = sqrt(x_edge .^ 2 + y_edge .^ 2);
  19
  20     if use_edges_mask
  21         magnitudes(~edges(2:end-1, 2:end-1)) = 0;
  22     end
  23
  24     disp('Applying Houg...');
  25     tic
  26     [acc_votes, acc_radius] = HTCircleGradient(magnitudes, [25, 35]);
  27     toc
  28
  29     disp('Finding ellipses...');
  30     tic
  31     ellipses = find_ellipses(acc_votes, acc_radius);
  32     toc
  33
  34     name = ['Hough gradient - ' image_name];
  35     if use_edges_mask
  36         name = [name ' (with edges)'];
  37     end
  38
  39     show_figures(name, {...
  40         {green_filtered, 'original filtered with a gaussian, sigma=1'},...
  41         {edges, 'edges (otsu -> dilate - erode)'},...
  42         {magnitudes, 'magnitudes'},...
  43         {expand_matrix(acc_votes), 'votes'}}, green, ellipses);
  44 end
  45