OpenCV error - cv2.cvtcolor

Question

I am a newbie to openCV and I am stuck at this error with no resolution. I am trying to convert an image from BGR to grayscale format using this code-

img = cv2.         


        

Answer 1

imagine you have a function called preprocessing() that preprocess your images with cv2, if you try to apply it as:

data = np.array(list(map(preprocessing,data)))

it won't work and that because np.array creates int64and you are trying to assign np.uint8 to it, what you should do instead is adding dtype parameter as follow:

data = np.array(list(map(preprocessing,data)), dtype = np.uint8)