opencv - How to apply CLAHE on RGB color images

Question

CLAHE is Contrast Limited Adaptive Histogram Equalization and a source in C can be found at http://tog.acm.org/resources/GraphicsGems/gemsiv/clahe.c

So far I have only seen some examples/tutorials about applying CLAHE on grayscale images so is it possible to apply CLAHE on color images (such as RGB 3 channles images)? If yes, how?

Answer 1

Conversion of RGB to LAB(L for lightness and a and b for the color opponents green–red and blue–yellow) will do the work. Apply CLAHE to the converted image in LAB format to only Lightness component and convert back the image to RGB. Here is the snippet.

bgr = cv2.imread(image_path)

lab = cv2.cvtColor(bgr, cv2.COLOR_BGR2LAB)

lab_planes = cv2.split(lab)

clahe = cv2.createCLAHE(clipLimit=2.0,tileGridSize=(gridsize,gridsize))

lab_planes[0] = clahe.apply(lab_planes[0])

lab = cv2.merge(lab_planes)

bgr = cv2.cvtColor(lab, cv2.COLOR_LAB2BGR)

bgr is the final RGB image obtained after applying CLAHE.