png转alpha图片

png转alpha

import cv2
import os

save_path = "/tmp/17527.png"
img_png = cv2.imread(save_path, cv2.IMREAD_UNCHANGED)

alpha = img_png[:, :, 3]
os.remove(save_path)  # 删除提取alpha 前的图片
# 保存 alpha 通道为灰度图
cv2.imwrite("/tmp/123_alpha.png", alpha)