How to count the number of pixels in each section of an image set?
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Gabriela Almeida
on 11 May 2022
Commented: Gabriela Almeida
on 12 May 2022
Hello:)
I have a set of 80 dicom images of lungs and I was wondering if there is an automatic way or a simple way to count the number of pixels belonging to the lung in each section.
Could anyone help me?
I've searched everywhere and I can't find a way to calculate the pixels of each image at the same time, I only got the total number of pixels in the set but thats not what i wanted..
Any kind of help is welcome.
Thank you :)
4 Comments
Image Analyst
on 12 May 2022
@Gabriela Almeida then you must not have discovered my Image Segmentation Tutorial in my File Exchange
Accepted Answer
Matt J
on 12 May 2022
A = imread('toyobjects.png');
A = A<100 | A>150; % some binary image
% get total number of pixels across all objects
pixtotal = regionprops('table',A,'Area')
7 Comments
Matt J
on 12 May 2022
Perhaps you are accidentally feeding the code the same image every time. Whatever the problem is, it's coming from parts of the code you haven't shown us. But you can see from the simplified examples we've given you that regionprops will work.
More Answers (1)
DGM
on 11 May 2022
Edited: DGM
on 11 May 2022
Depending on what your images are like and what you need, this may be a start. You can calculate the number of true (nonzero) pixels in an image using nnz(). If your image has more than one object, then it will include them all. If you have more than one object and you want the pixel count for each object, you can do that using bwconncomp()
A = imread('toyobjects.png');
A = A<100 | A>150; % some binary image
imshow(A)
% get total number of pixels across all objects
pixtotal = nnz(A)
% get number of pixels in each object
CC = bwconncomp(A);
pixperobj = cellfun(@numel,CC.PixelIdxList)
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