MATLAB: Weird Imhist beahviour seen

Image Processing Toolboximhist

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.

Best Answer

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.
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