search

diegorep / pypng

Automatically exported from code.google.com/p/pypng
0 stars 0 forks source link

pipcolour will not eliminate redundant alpha channel. #41

Open GoogleCodeExporter opened 8 years ago

GoogleCodeExporter commented 8 years ago 
Sometimes an image has an alpha channel that is effectively unused.  In which 
case pipcolours 
should eliminate it from the output.

The obvious case is when the alpha channel is all maxval.  But it could also be 
a colour mapped 
image with a tRNS chunk, but where all the indexes actually used correspond to 
completely opaque 
colours.  Or a non-colour mapped image with a tRNS chunk that indicated a 
colour not present in 
the image.

Original issue reported on code.google.com by d...@pobox.com on 1 Apr 2009 at 1:11