OMG. I take this is the direction Matlab is going. Very disappointing. Is this true for the latest Unix version as well?

Thanks,
Ljubomir

My old license just expired, taking with it my old version of MATLAB, which I had avoided upgrading because of the changes to imshow that require the use of the JVM. I much prefer running MATLAB in -nojvm mode, but I do a lot of image processing and now it seems as though I’m stuck with the JVM. Is there any way around this?

Thanks,
Arjun

And while you’re at it ;-), I would like a pixel list of the perimeter of the ‘FilledImage’ too!

regionprops has supported multidimensional label matrices since 2001, but not for every measurement. The descriptions for the individual measurements tell you which ones work for multidimensional L, and which ones work only for two-dimensional L. For example, the description for 'Centroid' starts with “1-by-ndims(L) vector …” The description for 'Eccentricity', on the other hand, says “This property is supported only for 2-D input label matrices.”

Your description sounds like you want multidimensional support in a different sense. You have a two-dimensional label matrix, and you want to compute the specified measurements corresponding to that label matrix for each plane of a three-dimensional array. This is a straightforward application of functionality that’s already in the product. For example, you might do something like this:

for k = 1:3
  means{k} = regionprops(L, rgb(:,:,k), 'MeanIntensity');
end

Boundary tracing has been available in the toolbox for a few releases. You could compute the boundaries for each labeled region this way:

[L, n] = bwlabel(L);
s = regionprops(L, 'Image');
for k = 1:numel(s)
  s(k).Boundaries = bwboundaries(s(k).Image);
end

I like your “use case” of plotting the outlines of labeled regions, and I’m going to suggest to the team that we add an example like that to the documentation.

Also, another obvious omission is the lack of returning the blob perimeter pixels. For the entire blob, you return the area and all the pixels that make up the area, yet for the perimeter, you only return the perimeter length and not all the pixels that make up the perimeter. Why not? Is it just an oversight or is it really that complicated to add. The work around I might try is to erode the binary image and then subtract the original (to get just the perimeter pixels), then label and regionprop that image to get PixelIDXList which would then represent only the perimeter pixels. Will you be adding this functionality directly into regionprops soon so that we do not have to resort to tricky workarounds to get the perimeter coordinates? The reason for the request is that after finding the blobs, I want to plot the perimeters of them on top of the original color or gray scale image.