Splitting Image using OpenCV in python

Question

I have an image and want to split it into three RGB channel images using CV2 in python.

I also want good documentation where I can find all the functions of openCV, as I am completely new to OpenCV.

Answer 1

That is as simple as loading an image using cv2.imread and then use cv2.split:

>>> import cv2 >>> import numpy as np >>> img = cv2.imread("foo.jpg") >>> b,g,r = cv2.split(img) 

OpenCV documentation is available from docs.opencv.org

Answer 2

As mentioned in the documentation tutorial, the cv2.split() is a costly operation in terms of performance(time) if you don't want to operate on all the channels but only one/two, so the numpy indexing is preferred:

import cv2 import numpy as np img = cv2.imread("foo.jpg") b = img[:,:,0] g = img[:,:,1] r = img[:,:,2] 

Remember that opencv reads the images as BGR instead of RGB

Edit: @Mitch McMabers, Thanks for pointing this out. Please use this method for max efficiency if you want to work on just one/two channels separately. If you want to operate on all three channels, access the channels using cv2.split() as mentioned in @jabaldeno's answer.