--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/mysite/photologue/utils/watermark.py	Mon Apr 06 03:10:59 2009 +0000
@@ -0,0 +1,64 @@
+""" 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()