"charlie clark" wrote:
> Trying to understand things: lut is effectively a palette table all set to
> the same value?
> What does lut[im.info["transparency"]] = 0 do?
> In my case its would sets lut[14] = 0
> So the real magic is im.point() which creates a single band presumably
> reacting to the transparency in the original image.
"point" just maps the source pixels through the lookup-table
(the "lut"), like this:
for all coordinates in image:
... load pixel from input image ...
pixel = lut[pixel]
... store pixel in output pixel ...
the result is a mask which has the value 0 for all transparent pixels
(index 14), and the value 1 for all other pixels. "point" itself doesn't
know about transparency; it just uses the table it got.
</F>
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