MATLAB: How to perform image segmentation

image processingImage Processing Toolboximage segmentation

I want to manually segment a small object(eg: a feature similar to cell nucleus) which is located within the original image. Can anyone kindly tell me what is the cause to obtain the boundary of the segmented image larger than the real image? (though i drew the boundary along the cell nucleus, segmented image still gives larger segmentation.

Thank you.

Best Answer

See my Image Segmentation Tutorial : http://www.mathworks.com/matlabcentral/fileexchange/25157-image-segmentation-tutorial

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MATLAB: Number of Object in binary image

Try this:

bw = imread('bw.png');
if ndims(bw) > 1
	bw = bw(:,:,1);
end
% Threshold
bw = bw > 128;
subplot(1, 2, 1);
imshow(bw, []);
% Fill holes
bw = imfill(bw, 'holes');
% Get areas
props = regionprops(bw, 'Area');
sortedAreas = sort([props.Area], 'descend')
% Looks like we need to throw away any blobs less than 1000 pixels or so
bw = bwareaopen(bw, 1000);
subplot(1, 2, 2);
imshow(bw);
% Count the blobs
[labeledImage, numBlobs] = bwlabel(bw);
fprintf('Found %d shapes.\n', numBlobs);

MATLAB: How to remove the background from a binarized image of which I selected a specific ROI

I'm confused. What is the "main matrix" part of the image? And what are pores and what is background? The images look the same, just cropped. I don't see any inverting nor do I see why it's needed.

I'll assume you want the white blobs but not the white circular surround. So simply use a circular template mask to get rid of it:

binaryImage(circularMask) = false;

or call imclearborder() to get rid of the circular surround

binaryImage = imclearborder(binaryImage);

imclearborder will also remove and partial blobs crossing the circular border, which is not a bad thing - just depends if you want area fraction and partial blobs are okay, or if you need complete blobs for your computations.

Then call imrect() or rbbox() to define the cropping rectangle, call imcrop() or use indexing to actually make the crop, and you're done.

Best Answer

Related Solutions

MATLAB: Number of Object in binary image

MATLAB: How to remove the background from a binarized image of which I selected a specific ROI

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