[Clipart] Logo, blue on blue.

[Jonadab the Unsightly One]

Alan Horkan <horkana at maths.tcd.ie> writes:

>> http://pmt.sf.net/opossum
>
> This Gif on the lower left looks fine

The PNG looks quite significantly better.  However, this is really a
different situation from the OpenClipart.org logo, which is rendered
in a solid _rectangular_ image and has no need of transparency.  It
can use whatever antialiasing is desired within that rectangle, but
the edges are vertical and horizontal, so no jaggies there.  So it
could be indexed without creating any problems.

There are two kinds of antialiasing:  known-background, and
alphachannel.  Known-backround antialiasing doesn't mix well with
transparency, and alphachannel antialiasing doesn't mix with indexing.

So you choose between indexing and transparency, and the choice
dictates which kind of antialiasing is available to you.  If you
insist on indexing _and_ transparency (as with transparent-backed
GIFs), then you don't AA the edges because that makes a mess, but in
general I find that indexed formats aren't very good for transparency
anyway.

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