你是這個意思？:

import cv2

import numpy as np

img = cv2.imread("image.jpg")

hsv = cv2.cvtColor(img, cv2.COLOR_BGR2HSV)

mask = cv2.inRange(hsv, (0, 0, 0), (75, 255, 255))

imask = mask > 0

green = np.zeros_like(img, np.uint8)

green[imask] = img[imask]

cv2.imwrite("result.png", green)

輸出