import Image, ImageEnhance
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 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()
