OpenCV: filter by color in image

Question

How can you display only a single color from a RGB image with OpenCV in python ? The idea is to be able to print the image in a grey scale corresponding to the intensity of a certain color in the RGB spectrum.

Answer 1

You can either use split:

blue, green, red = cv2.split(img)

Or, as this is a costly operation in terms of time and you only need one of the channles (for instance, red) you can directly slice the original image like as follows:

red = img[:,:,2]

Which will return a greyscaled image where the brighter pixels are the ones that have higher red values in the original image.

Hope this helped!