MATLAB: How to measure dimensions of region boundary plot

bwboundariesimage processingImage Processing Toolboxobject boundaryobject segmentationregion boundary

Hello,
I have an image (from MATLab example) and I want to know the number of pixels in/dimensions of the green boundary. As according to the code, the green boundary is overlaid on the image and is not a part of the image, I am unable to calculate its length or the number of pixels it has.
BW = imread('blobs.png');
Calculate boundaries.
[B,L,N] = bwboundaries(BW);
Display object boundaries in red and hole boundaries in green.
imshow(BW); hold on;
for k=1:length(B),
   boundary = B{k};
   if(k > N)
     plot(boundary(:,2), boundary(:,1), 'g','LineWidth',2);
   else
     plot(boundary(:,2), boundary(:,1), 'r','LineWidth',2);
   end
end
I want to make the green boundary a part of the image so that I can count its number of pixels too. Or any other way to do just that (measure the length of the green region).
Please help me in this regard.
Regards.

Best Answer

Just get the size of boundary in the loop:
numPixels(k) = size(boundary, 1); % Count rows.
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