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- """ Function for applying watermarks to images.
- Original found here:
- http://aspn.activestate.com/ASPN/Cookbook/Python/Recipe/362879
- """
- try:
- import Image
- import ImageEnhance
- except ImportError:
- try:
- from PIL import Image
- from PIL import ImageEnhance
- except ImportError:
- raise ImportError("The Python Imaging Library was not found.")
- def 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 im
- def apply_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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