Converts an image to grayscale using the crude average of the r, g, and b

def convertToGray(img):
  # loop over each pixel
  for r in range(img.shape[0]):
    for c in range(img.shape[1]):
      # get the avg of the r, g, b values
      avg = int((img[r, c, 0] + img[r, c, 1] + img[r, c, 2])/3)
      # set the pixel to the avg value
      img[r, c] = [avg, avg, avg]
  return img