Graphics Reference
In-Depth Information
.gif
Due to the cost of graphics cards that rendered more than 256 colors
at the time the .gif format was first introduced, .gif files themselves
were limited to a palette of 256 colors. Because of this limitation,
.gifs are most useful for graphics with fewer colors than you would
find in a photographic image; graphics such as diagrams, cartoon-
style drawings or any other imagery that is intended to use a limited
color palette. .gifs use a different compression method from .jpgs
called
Lossless data compression differs from lossy data
compression in that it allows the exact original data to be recon-
structed from the compressed data and this exact reconstruction is
very important when image details must be seen clearly.
Unlike .jpgs, .gifs support image transparency. However, it
lossless.
s
important to remember that when you create a .gif with transparent
areas, you
'
ll get a single pixel of solid color around the nontranspar-
ent area. This works fine if the background of your animation is the
same solid color, but not so well if your background is multicolored
or gradient. See Figs. 5.5 and 5.6 for examples of the same .gif on
different backgrounds.
'
TIP
It should be noted that .gifs support frame-based animations and that
these .gif animations may be a great choice for your non-Flash backup
image.
Figure 5.5 A .gif with transparency on a solid white
background.
Figure 5.6 A .gif with transparency on a gradient
background.
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