Display an image processed in LAB channel
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I'm dealing with processing blood vessels image in LAB channels, first i Convert the image to LAB color space, then i applied Contrast Limited Adaptive Histogram Equalization (CLAHE) to L channel, finally i converted the enhanced LAB image back to RGB color space.
% Load an image
originalImage = imread('7roi.png');
% Convert the image to LAB color space
labImage = rgb2lab(originalImage);
labImage = im2double(labImage);
% Apply Contrast Limited Adaptive Histogram Equalization (CLAHE) to L channel
clabImage = labImage;
clabImage(:,:,1) = adapthisteq(labImage(:,:,1));
% Convert the enhanced LAB image back to RGB color space
enhancedRGBImage = lab2rgb(clabImage);
% Convert enhanced image back to the original data type
enhancedRGBImage = im2uint8(enhancedRGBImage);
figure
imshow(enhancedRGBImage);
Here is the original and the result image, is it normal or i have some mistake in my algorithm, please help, thank you so much.


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Accepted Answer
DGM
on 30 Aug 2023
Edited: DGM
on 30 Aug 2023
LAB images from rgb2lab() are not on the same scale expected of RGB images. You'll need to rescale the data appropriately if you want to feed it to something that isn't expecting that sort of range.
% Load an image
originalImage = imread('https://www.mathworks.com/matlabcentral/answers/uploaded_files/1467156/image.png');
% Convert the image to LAB color space
labImage = rgb2lab(originalImage);
% there's no need to convert to double when using lab2rgb()
% Apply Contrast Limited Adaptive Histogram Equalization (CLAHE) to L channel
% adapthisteq() expects floating point images to be in unit-scale (0 to 1)
% but this LAB representation is not unit-scale
clabImage = labImage;
clabImage(:,:,1) = adapthisteq(labImage(:,:,1)/100)*100; % rescale L as needed
% Convert the enhanced LAB image back to RGB color space
enhancedRGBImage = lab2rgb(clabImage);
% Convert enhanced image back to the original data type
enhancedRGBImage = im2uint8(enhancedRGBImage);
figure
imshow(enhancedRGBImage);
... or if you were using MIMT, you could do the whole thing in one line without worrying about scale or truncation:
enhancedRGBImage = histeqtool(originalImage,'ahisteqlchab');
More Answers (1)
Image Analyst
on 29 Aug 2023
The code looks right. The problem is that CLAHE is often not a good algorithm because it's non-linear. Try imadjust instead.
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