relative-darkness issue

[justinner]

Hi Chris,
When I run the function relative_darkness,I got nothing ,and no error,no result.The following is my code run it ,could you tell me why it happened?Thanks very much.
img = cv2.imread('/home/jia/1.bmp', cv2.IMREAD_GRAYSCALE)
rd_img = relative_darkness(img)
data = np.concatenate([img[:,:,np.newaxis], rd_img], axis=2)
if debug:
cv2.imwrite('/home/jia/Dataset/rd/rd.bmp', rd_img)
data = 0.003921568 * (data - 127.)
print(data.shape)