Weird Imhist beahviour seen
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Hi, ive been tearing my hair out all morning. I want to plot the histogram of an image. I normally use im hist. My images are 3 12 bit images that are summed, hence the max value can be 3*4095=12285. It appears my histogram is defaulting to 16 bit values.
This is my code:
IM = imread(file);
IM1=double(IM);
[maxval,idx]=max(IM1(:)) % determine number of bins (of width = unity)
maxval= double(maxval);
[counts,x] = imhist(IM,maxval);
figure
stem(x,counts,'b', '.');
counts(maxval) %check the max intensity
First of all, counts(maxval) returns zero, and here is the histogram stem plot - defaulting to 65535 levels. I want to have 1-12285 levels.
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Accepted Answer
Image Analyst
on 21 Nov 2014
Try this:
grayImage = imread(file);
maxGrayLevel = max(grayImage(:)) % determine max gray level.
[counts, grayLevels] = imhist(grayImage);
bar(grayLevels, counts, 'Color', 'b');
xlim([0, maxGrayLevel)]; % Specify range of x axis.
Let me know how it works.
2 Comments
Image Analyst
on 21 Nov 2014
You're welcome. Can you go ahead and officially mark the answer as "Accepted" then? Thanks in advance.
More Answers (1)
DGM
on 20 May 2024
I don't know where everyone is getting uint12-scale images, but I guess it's a thing. I posted an example which demonstrates three ways of representing improperly scaled images (uint12 in uint16, and int12 in int16) using imhist() and other tools.
2 Comments
DGM
on 20 May 2024
Oh wow. I didn't even notice both threads were yours. I certainly didn't expect a prompt reply!
You're welcome.
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