GeodSoft.com Graphics and Color Reduction
A brief discussion of optimizing graphic file sizes by reducing the
number of colors follows.
With three essentially identical sites on different platforms I
thought it would be important to make some visual distinction
between which was which. I decided to use the "powered by" graphics
provided by the OS and web server vendors. I made some minor
size and proportion adjustments; I hope the vendors don't
object. Mostly I greatly reduced the number of colors in each to
reduce file sizes. One would think by now that all web
professionals know about palette reduction as means to reduce
graphic size (and prevent palette conflicts on color limited,
i.e. 256 color, monitors) but based on the powered by graphics
this does not seem to be the case.
The worst offender was the powered by Open BSD graphic. At
first glance this looks like it has only about six colors, red,
yellow, two shades of blue, black and white. The image is
shaded so the number is much larger. It was actually
just under the maximum 256 colors for a .gif, mostly a huge
variety of red shades. Macromedia's
Fireworks took this down to 32 colors
automatically with almost no loss of quality.
While my personal experience
is still limited, Fireworks 2 provides the most controllable and
comprehensive palette reduction options. I'm sure 3 is even
better but I bought my copy of 2 just a few days before
Macromedia announced the release of 3 and they would not give me
any price break on an upgrade so I'll wait for 4 before giving
them more of my money. In many ways Photoshop 5.5 is clearly a
more refined and easier to use product than Fireworks which
still shows its immaturity but I can find nothing in Photoshop
or its companion ImageReady that gives any where near the palette
reduction choices that Fireworks does.
When I said automatic above, actually Fireworks has an
automatic reduction when you pick "WebSnap Adaptive" when
exporting a .gif but once you see the number of colors left
you can still force further reductions buy picking a power of
2 less than the fully automatic number. Often you can force
a substantial reduction in colors and hence file size with
very little loss of quality. Further, you can even manually
eliminate individual colors to create a custom palette.
The Microsoft graphics for Internet Information Server and
BackOffice appeared to have a fair number of colors because
of the colored ribbons but they had already been pretty well
reduced with only 55 colors in the BackOffice graphic. Trying
to force this to 32 really changed the appearance but by
manually deleting the colors that had others that were very
close, I was able to reduce this to 32 colors with almost no
loss of quality.
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