使用 cv2.imread：“<built-in function imread> 没有设置错误就返回NULL”，好像无法打开图片或获取数据</built-in>

Question

This is the part of my code that gives the problem. It is supposed to count the amount of green pixels in a picture:

img = Image.open('path.tif')

BLACK_MIN = np.array([0, 20, 20], np.uint8)

BLACK_MAX = np.array([120, 255, 255], np.uint8)

imgg = cv2.imread(img, 1)

dst = cv2.inRange(imgg, BLACK_MIN, BLACK_MAX)

no_black = cv2.countNonZero(dst)

print('The number of black pixels is: ' + str(no_black))

Answer 1

You are passing a PIL image to imread but it expects a filepath ( https://docs.opencv.org/2.4/modules/highgui/doc/reading_and_writing_images_and_video.html?highlight=imread#Mat%20imread(const%20string&%20filename,%20int%20flags)

You should use:

imgg = cv2.imread('path.tif', 1)

Answer 2

Image is already readed using PIL.Now the img is in array format so you cannot able to read it again.Read your file in any one kind of format either pil or cv2

BLACK_MIN = np.array([0, 20, 20], np.uint8)

BLACK_MAX = np.array([120, 255, 255], np.uint8)

imgg = cv2.imread('path.tif', 1)

dst = cv2.inRange(imgg, BLACK_MIN, BLACK_MAX)

no_black = cv2.countNonZero(dst)

print('The number of black pixels is: ' + str(no_black))