How to fast change image brightness with python + OpenCV?

Question

I have a sequence of images. I need to average brightness of these images.

First example (very slow):

img = cv2.imread(\'test.jpg\')         


        

Answer 1

Iterating over the whole image to make changes is not a very scalable option in opencv, Opencv provides a lot of methods and functions to perform the arithmetic operations on the given image.

You may simply split the converted HSV image in the individual channels and then process the V channel accordingly as:

img = cv2.imread('test.jpg') #load rgb image
hsv = cv2.cvtColor(img, cv2.COLOR_BGR2HSV) #convert it to hsv

h, s, v = cv2.split(hsv)
v += 255
final_hsv = cv2.merge((h, s, v))

img = cv2.cvtColor(final_hsv, cv2.COLOR_HSV2BGR)
cv2.imwrite("image_processed.jpg", img)