MACROMEDIA FLASH MX 2004-USING FLASH Use Manual page 321

Select one of the following Transparent options to determine the transparency of the
7.
application's background and the way alpha settings are converted to GIF:
Opaque
makes the background a solid color.
Transparent
makes the background transparent.
Alpha
sets partial transparency. You can enter a Threshold value between 0 and 255. A lower
value results in greater transparency. A value of 128 corresponds to 50% transparency.
Select a Dither option to specify how pixels of available colors are combined to simulate colors
8.
not available in the current palette. Dithering can improve color quality, but it increases the file
size. Select from the following options:
None turns off dithering and replaces colors not in the basic color table with the solid color
from the table that most closely approximates the specified color. Turning dithering off can
result in smaller files but unsatisfactory colors.
Ordered
provides good-quality dithering with the smallest increase in file size.
Diffusion
provides the best-quality dithering but increases file size and processing time. It also
works only with the web 216 color palette selected.
Select one of the following Palette Types to define the image's color palette:
9.
Web 216 uses the standard 216-color, browser-safe palette to create the GIF image, for good
image quality and the fastest processing on the server.
Adaptive
analyzes the colors in the image and creates a unique color table for the selected
GIF file. This option is best for systems displaying thousands or millions of colors; it creates
the most accurate color for the image but increases file size. To reduce the size of a GIF with
an adaptive palette, use the Max Colors option in step 10 to decrease the number of colors in
the palette.
Web Snap Adaptive
to the web 216 color palette. The resulting color palette is optimized for the image, but when
possible, Flash uses colors from the web 216 palette. This produces better colors for the image
when the web 216 palette is active on a 256-color system.
Custom specifies a palette that you have optimized for the selected image. The custom palette
is processed at the same speed as the web 216 palette. To use this option, you should know
how to create and use custom palettes. To select a custom palette, click the Ellipsis (...) button
to the right of the Palette box at the bottom of the dialog box and select a palette file. Flash
supports palettes saved in the ACT format, exported by Macromedia Fireworks and other
leading graphics applications; for more information, see
palettes" on page 83.
If you selected the Adaptive or Web Snap Adaptive palette in step 9, enter a value for Max
10.
Colors to set the number of colors used in the GIF image. Selecting a smaller number of colors
can produce a smaller file but can degrade the colors in the image.
Click OK to save the settings with the current file.
11.
is the same as the Adaptive palette option except it converts similar colors
"Importing and exporting color
Publishing Flash documents 321