python 图片打水印 透明图片合并

下面的例子是将img2作为水印打到bg上，注意：img2是一个背景透明的png

import cv2
from PIL import Image

def merge_image(bg, img2, top_left):
    # 打开背景
    bg = Image.fromarray(bg.astype('uint8')).convert('RGB')
    # 创建底图
    target = Image.new('RGBA', (bg.size[0], bg.size[1]), (0, 0, 0, 0))
    # 打开水印
    img2_scale = img2.copy()
    # img2_scale = cv2.resize(img2_scale, (w2, h2))
    img2_scale = Image.fromarray(img2_scale.astype('uint8')).convert('RGBA')
    # 分离透明通道
    r, g, b, a = img2_scale.split()
    # 将背景贴到底图
    bg.convert("RGBA")
    target.paste(bg, (0, 0))
    # 将水印贴到底图
    img2_scale.convert("RGBA")
    startX = top_left[0]
    startY = top_left[1]
    target.paste(img2_scale, (startX, startY), mask=a)
    target = np.array(target)
    return target

bg = cv2.imread(r'bg.jpg')
    img2 = cv2.imread(r'logo.png', cv2.IMREAD_UNCHANGED)
    top_left = (10, 10)
    res = merge_image(bg, img2, top_left)
    cv2.imshow('1', res)
    cv2.waitKey(100000)