Python中的绿屏效果？

Question

基本上，我只需要擦除其中一张图像中的绿色屏幕像素，然后将其重叠在背景图像上即可。这两张图片的大小相同。

pic1 = "C:\Users\user\Desktop\greenscreen.png"
pic2 = "C:\Users\kazan\Desktop\background.png"
picture = makePicture(pic1)
picture2 = makePicture(pic2)
greenPix = getPixels(picture)
bgPix = getPixels(picture2)
greenValue = []
counter = 0
for pixels in getPixels(picture2):
  xLoc = getX(pixels)
  yLoc = getY(pixels)
  r = getRed(pixels)
  g = getGreen(pixels)
  b = getBlue(pixels)
  setRed(pixel,255-r)
  setGreen=(pixel,255-g)
  setBlue=(255,-b)
explore(picture2)

如何将绿色屏幕图片叠加到背景图片上？我觉得我要去某个地方，但我肯定还没到那儿。