Transparent PNG in PIL turns out not to be transparent
I think what you want to use is the paste mask argument.see the docs, (scroll down to paste)
from PIL import Imageimg = Image.open(basefile)layer = Image.open(layerfile) # this file is the transparent oneprint layer.mode # RGBAimg.paste(layer, (xoff, yoff), mask=layer) # the transparancy layer will be used as the maskimg.save(outfile)