I have three RGB images, but each one has only 1 non-zero channel (ie. one has a red channel with 0's in the blue and green channels) and I want to combine them into a single RGB image with the correct channel from each.

I apologise for my phrasing, I don't know much of the terminology (which really isn't helping my search queries)

Here are my images: Blue Green Red

You can also use OpenCV:

blue = cv2.imread("blue.jpg")
red = cv2.imread("red.jpg")
green = cv2.imread("green.jpg")merge = blue + red + green
cv2.imwrite('merge.jpg', merge)