import cv2
import numpy as np
image = np.zeros((100, 100, 3), dtype=np.uint8)
image[25:75, 25:75] = (0, 255, 0)
hsv = cv2.cvtColor(image, cv2.COLOR_BGR2HSV)
mask = cv2.inRange(hsv, np.array([40, 80, 80]), np.array([80, 255, 255]))
print(int(np.count_nonzero(mask)))
cv2.imwrite("mask.png", mask)