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May
19
GIF
Transparency in Fireworks 3
by
David Nagel
Executive Producer
This
is a quick tutorial to help you improve the look of your GIFs. There comes a time
in every Web developer's life when it becomes necessary to use transparency in
an image. Maybe you need to float an image over a repeating background. Maybe
you need to animate a foreground image over a photographic background. Whatever
it is, you're desperate because plainly GIFs are inferior to JPEGs, and GIF transparency
is, ultimately, a hideous atrocity against art. That
said, let's get started.
We're
going to put a flaming logo on top of a photographic background. This is never
a very good idea. Flames are, in themselves, partially transparent, and GIFs can't
handle this. In a GIF, it's all or nothing. So let's look at some examples. Above
is our flamey logo. We want to put it over a picture of a forest, like the image
on the right. The image on the right, however, is a JPEG, so the logo is not independent
of the background.
So,
given that we need to make the logo independent of the background, we'd best turn
it into a GIF. The first thing you'll want to do is get Fireworks
3 from Macromedia. No other graphics application can handle GIF transparency
like Fireworks. After you've done this, turning your GIF into something almost
passable isn't all that tough. In fact, it's really just a matter of selecting
the highest-quality optimization and playing with the matte settings to match
your background. The matte settings will help eliminate artifacts and minimize
the effects of edge pixelization. You can see in the following example that even
with the maximum palette setting, a white matte will leave artifacts and, in general,
ugly up the whole image.

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Here's
the logo on the background image saved as a GIF: Adaptive, 256 colors, 0 Loss,
0, Dither, Alpha Transparency, White Matte.
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Now take
a look at some different settings. Each can be appropriate in the right circumstance.
For our purposes here, the last two settings produce the best results.

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GIF:
Web 216, 216 colors, 0 Loss, 100% Dither, Alpha Transparency, Black Matte.
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GIF:
Web 216, 216 colors, 0 Loss, 100% Dither, Index Transparency, No Matte.
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GIF:
Web Adaptive, 256 colors, 0 Loss, 0 Dither, Alpha Transparency, Black Matte.
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GIF:
Web Adaptive, 256 colors, 0 Loss, 0 Dither, Alpha Transparency, No Matte.
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For more information
on Fireworks, visit our Macromedia
Fireworks user forum or post a message in the Creative
Mac World Wide User Forum.
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