图像圆度计算

Halcom

https://ww2.mathworks.cn/help/im ... -round-objects.html
metric = 4*pi*area/perimeter^2.

1. [B,L] = bwboundaries(bw,'noholes');
   
2. 
   
3. % Display the label matrix and draw each boundary
   
4. imshow(label2rgb(L, @jet, [.5 .5 .5]))
   
5. hold on
   
6. for k = 1:length(B)
   
7.   boundary = B{k};
   
8.   plot(boundary(:,2), boundary(:,1), 'w', 'LineWidth', 2)
   
9. end
   
10. 
    
11. stats = regionprops(L,'Area','Centroid');
    
12. 
    
13. threshold = 0.94;
    
14. 
    
15. % loop over the boundaries
    
16. for k = 1:length(B)
    
17. 
    
18.   % obtain (X,Y) boundary coordinates corresponding to label 'k'
    
19.   boundary = B{k};
    
20. 
    
21.   % compute a simple estimate of the object's perimeter
    
22.   delta_sq = diff(boundary).^2;   
    
23.   perimeter = sum(sqrt(sum(delta_sq,2)));
    
24.   
    
25.   % obtain the area calculation corresponding to label 'k'
    
26.   area = stats(k).Area;
    
27.   
    
28.   % compute the roundness metric
    
29.   metric = 4*pi*area/perimeter^2;
    
30.   
    
31.   % display the results
    
32.   metric_string = sprintf('%2.2f',metric);
    
33. 
    
34.   % mark objects above the threshold with a black circle
    
35.   if metric > threshold
    
36.     centroid = stats(k).Centroid;
    
37.     plot(centroid(1),centroid(2),'ko');
    
38.   end
    
39.   
    
40.   text(boundary(1,2)-35,boundary(1,1)+13,metric_string,'Color','y',...
    
41.        'FontSize',14,'FontWeight','bold');
    
42.   
    
43. end
    
44. 
    
45. title(['Metrics closer to 1 indicate that ',...
    
46.        'the object is approximately round']);

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