How can I plot the diameters of an irregularly shaped region in an image?

This is my code:

props = regionprops(BW, 'Area', 'Perimeter','Centroid','EquivDiameter');
allAreas = [props.Area];
allPerimeters = [props.Perimeter];
centroids = cat(1, props.Centroid);
allDiameters = [props.EquivDiameter];
figure(1);
imshow(BW);
title('Outlines, from bwboundaries()', 'FontSize', 1); 
axis image; % Make sure image is not artificially stretched because of screen's aspect ratio.
hold on;
boundaries = bwboundaries(BW);
numberOfBoundaries = size(boundaries, 1);
for k = 1 : numberOfBoundaries
  thisBoundary = boundaries{k};
  plot(thisBoundary(:,2), thisBoundary(:,1), 'r', 'LineWidth', 2);
end
hold on;
plot(centroids(:,1),centroids(:,2), 'b*')
hold off

This gives me the following image:

I got the actual values of the diameters through "EquivDiameter", but how can I plot the diameters of each individual blob on top of their centroids?

Answer 1

[Image Analyst]

Try this:

xCentroids = centroids(1:2:end);
yCentroids = centroids(2:2:end);
for k = 1 : length(xCentroids )
  txt = sprintf(' %.2f', allDiameters(k));
        text(xCentroids(k), yCentroids(k), txt, 'FontSize', 20, 'FontWeight', 'bold');
end

[Asher Zaidi]

That gives me this (I changed the font to green to make it visible):

Code Used:

 props = regionprops(BW, 'Area', 'Perimeter','Centroid','EquivDiameter');
allAreas = [props.Area];
allPerimeters = [props.Perimeter];
centroids = cat(1, props.Centroid);
allDiameters = [props.EquivDiameter];
figure(1);
imshow(BW);
title('Outlines, from bwboundaries()', 'FontSize', 1); 
axis image; % Make sure image is not artificially stretched because of screen's aspect ratio.
hold on;
boundaries = bwboundaries(BW);
numberOfBoundaries = size(boundaries, 1);
for k = 1 : numberOfBoundaries
  thisBoundary = boundaries{k};
  plot(thisBoundary(:,2), thisBoundary(:,1), 'r', 'LineWidth', 2);
end
hold on;
plot(centroids(:,1),centroids(:,2), 'b*')
xCentroids = centroids(1:2:end);
yCentroids = centroids(2:2:end);
for k = 1 : length(xCentroids )
  txt = sprintf(' %.2f', allDiameters(k));
        text(xCentroids(k), yCentroids(k), txt,'Color','green' ,'FontSize', 20, 'FontWeight', 'bold');
end
hold off

[Image Analyst]

OK. You might make the font size a bit smaller. Honestly I don't know why you want the diameters on the image if there are so many of them.

But anyway, if I've answered all your questions, can you click the "Accept this answer" link?

[Asher Zaidi]

Sure, thanks!

Answer 2

[Matt J]

You can use the text() command to write the diameters onto the image at desired locations.