[Image-SIG] Poor Image Quality When Resizing a GIF

[douglas bagnall]

hi Andy

> Here's the resized gif with the original code I pasted.  You'll see a
> bunch of 'dots' throughout the image:
> http://www.andymccurdy.com/resized_1.gif

PIL uses the so-called "web palette" by default.  Your image uses
#fdfdfd for white, but the web palette uses #ffffff. So it dithers to
approximate #fdfdfd.  You probably really want the background to be
pure #ffffff white, because printers etc will also dither, but the
more immediate problem is the web palette. Try this:

pil_image = pil_image.convert("P", palette=Image.ADAPTIVE)

or

pil_image = pil_image.convert("P", dither=Image.NONE, palette=Image.ADAPTIVE)

These options are not well documented, but you can find them in the
PIL/Image.py source.

douglas