> do NOT use png's.  they are are in general poorly supported by all web
> browsers.  use .gif or .jpg.

Please don't follow this advise. PNG's include a plenty of features like
alpha-transparency, great interlacing and gamma information. Wherever you wan't
to use a static GIF, PNG's can fit very well, since they support both indexed
and realcolor depths. PNG uses a non-lossy compression so it's great for
archival purposes too. GIF is a patent-bloated aging format that should
disappear from the web.

The problem of lacking browser support is not that hot, since number of v3
browsers is decreasing. Unfortunately only bleeding edge browsers (mozilla,
gtkhtml, dunno about IW) support features like alpha-transparency, but you can
safely live with 1bit mask as in GIF.

For the problem addressed, JPEG is much worse, since the color information is
stored using alossy compression formula and is always "similar" to the original
color... PNG can give the same functionality of GIF as described later...

Marc Lehmann also said:
>This is expected when you dither the image, so best do not convert your
>image to indexed format.

There are two tricks when using indexed images:
1) Use 1bit transparency. Get rid the background color. If you don't want
to dither to transparency or have rough edges, use the "semi-flatten" plugin.
index and save as png. Even crappy NN4 should handle it.

2) get rid of the dithering:
        - use web safe pallette when indexing (crap results)
        - use web safe pallette color when working in RGB mode (for the
          bacground). Generate an optimized pallette

          in the second case, there might be problems with dithering, so either:
           - don't use dithering
           - select the bcg area using magic wand, index the image using
             dithering, fill the selection with the web safe color.

Hope it helped

Jakub Steiner
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"even a stopped clock gives a right time twice a day"

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