MATLAB: How to crop images in Matlab based on Intensity Profiles

image processingImage Processing Toolboximage segmentationMATLAB

I have an image in Matlab which I want to crop based on the intensity profile. Below is my image.
I want to crop out the blue portion of the image based on the intensity profile. For example, based on the intensity profile, I want to crop the part of the image where the intensity of blue is higher than the other colors. Below is my sample code and example.
hFig = figure ; 
subplot(1, 2, 1 ); 
rgbImage = imread('Intensity1.jpg '); 
imshow(rgbImage ) 
subplot(1, 2, 2 ); 
croppedImage = rgbImage(200 : 400 , :, :); 
imshow(croppedImage);
In the image above, it can be seen that the blue portions still remain in the image which I don't want. Any help would be very much appreciated. Thank you.

Best Answer

Try this where img is your original image:
% get red, green, blue channels
redC = img(:,:,1);
greenC = img(:,:,2);
blueC = img(:,:,3);
% mask where red channel is greater than blue channel and green channel greater than blue channel
mask = redC > blueC & greenC > blueC;
% overlay mask into original image
finalimg = bsxfun(@times, img, cast(mask,class(img)));
%plotting
figure
subplot(1,2,1)
imshow(img)
subplot(1,2,2)
imshow(finalimg)
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