import image, imageenhancedef reduce_opacity(im, opacity): returns an image with reduced opacity. assert opacity >= 0 and opacity <= 1 if im.mode != 'rgba': im = im.convert('rgba') else: im = im.copy() alpha = im.split()[3] alpha = imageenhance.brightness(alpha).enhance(opacity) im.putalpha(alpha) return imdef watermark(im, mark, position, opacity=1): adds a watermark to an image. if opacity < 1: mark = reduce_opacity(mark, opacity) if im.mode != 'rgba': im = im.convert('rgba') # create a transparent layer the size of the image and draw the # watermark in that layer. layer = image.new('rgba', im.size, (0,0,0,0)) if position == 'tile': for y in range(0, im.size[1], mark.size[1]): for x in range(0, im.size[0], mark.size[0]): layer.paste(mark, (x, y)) elif position == 'scale': # scale, but preserve the aspect ratio ratio = min( float(im.size[0]) / mark.size[0], float(im.size[1]) / mark.size[1]) w = int(mark.size[0] * ratio) h = int(mark.size[1] * ratio) mark = mark.resize((w, h)) layer.paste(mark, ((im.size[0] - w) / 2, (im.size[1] - h) / 2)) else: layer.paste(mark, position) # composite the watermark with the layer return image.composite(layer, im, layer)def test(): im = image.open('test.png') mark = image.open('overlay.png') watermark(im, mark, 'tile', 0.5).show() watermark(im, mark, 'scale', 1.0).show() watermark(im, mark, (100, 100), 0.5).show()if __name__ == '__main__': test()
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