Re: IR users, please..

At 7:04 PM 3/14/99, Chris Hawkins wrote:
>I'm having intermittent luck with the dithering around gifs, and I think it
>has to do with when I'm saving optimized images.
>Please review for me what selecting "matte" does.  The manual is zero help.
>Is a particular matte color used to blend edge pixels, in transparencies?

Yes, a "matte" is helpful when you're trying to antialias the edges of
artwork to a given background.

Context: When you make a single color transparent in GIF, then antialiased
edges of the art will necessarily have a "halo". For instance, if the
canvas is white, then you'll see a fringe of whitish pixels around the
transparent GIF. That's because the artwork is being blended to the
background -- when the background is removed, you'll still see the
blending. (When Photoshop uses a "transparent" canvas it will antialias
edge pixels to white.)

For instance, suppose you're using a tiling background GIF of green leaves,
and you wish your logo to be non-rectangular and appear to antialias
smoothly into the background. If you use a green matte color and set green
to be transparent, then your logo will antialias to generic green which
will appear quite smooth against the background leaves.


(Note: My own trial version of ImageReady timed out long ago, but I assume
it's using the same handling here as Fireworks does. The Fireworks 2.0 demo
is now available in a fully-functional 30-day tryout version... it's an
exceptional tool, and may well be very worth your consideration.)

jd





John Dowdell, Macromedia Tech Support, San Francisco CA US
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