Alpha融合 Python-OpenCV

import numpy as np
import cv2

def paste_ROI_to_image(img1, img2, area):
    image1 = img1.copy()

    #改变尺寸
    # y1, x1, y2, x2 = area
    # img2 = cv2.resize(img2, (x2 - x1 + 1, y2 - y1 + 1))  # cv.resize(src, dsize=(width, height))

    image1 = image1.astype(np.float)  # 类型转换为np.float
    img2 = img2.astype(np.float)
    # alpha通道
    # alpha_image1 = image1[y1:y2 + 1, x1:x2 + 1, 3] / 255.0 #特定区域
    alpha_image1 = image1[:, :, 3] / 255.0 #整景影像
    alpha_img2 = img2[:, :, 3] / 255.0
    alpha = 1 - (1 - alpha_image1) * (1 - alpha_img2)
    # BGR通道
    for i in range(3):
        # image1[y1:y2 + 1, x1:x2 + 1, i] = (image1[y1:y2 + 1, x1:x2 + 1, i] * alpha_image1 * (1 - alpha_img2) + img2[:, :, i] * alpha_img2) / alpha     #放到特定位置                                                                                             
        image1[:, :, i] = (image1[:, :, i] * alpha_image1 * (1 - alpha_img2) + img2[:, :, i] * alpha_img2) / alpha
    image1[:, :, 3] = alpha * 255
    image = image1.astype(np.uint8)
    return image


if __name__ == "__main__":
    image1 = cv2.imread("cut\1.png", cv2.IMREAD_UNCHANGED)
    image2 = cv2.imread("cut\2.png", cv2.IMREAD_UNCHANGED)
    image = paste_ROI_to_image(image1, image2, [0, 0, 255, 255])
    cv2.imwrite("cut\3.png", image)