How to Mask an image using Numpy/OpenCV?

Question

I have an image I load with:

im = cv2.imread(filename)

I want to keep data that is in the center of the image. I created a circle as a mas

Answer 1

Use cv2.bitwise_and and pass the circle as mask.

im = cv2.imread(filename)
height,width,depth = im.shape
circle_img = np.zeros((height,width), np.uint8)
cv2.circle(circle_img,(width/2,height/2),280,1,thickness=-1)

masked_data = cv2.bitwise_and(im, im, mask=circle_img)

cv2.imshow("masked", masked_data)
cv2.waitKey(0)