MACROMEDIA FIREWORKS 8, Use Manual

Page: 344 / 472

344 Chapter 14: Optimizing and Exporting
Making areas transparent
You can set transparent areas for GIFs and 8-bit PNGs so that in a web browser the
background of the web page is visible through those areas. In Fireworks, a gray-and-white
checkerboard on document previews denotes transparent areas.
Optimized image preview in Fireworks; image exported with transparency and placed on a web
page with a colored background
You should use index transparency when exporting GIF images that contain transparent areas.
With index transparency, you set specific colors to be transparent upon export. Index
transparency turns on or turns off pixels with specific color values. Because GIFs support
index transparency, it is the most common form of transparency used on the web.
You can also use alpha transparency, although it is not often used with web graphics because
only PNGs support it and most web browsers do not support PNG format. Alpha
transparency is often used in exported graphics that contain gradient transparency and semi-
opaque pixels. Alpha transparency is also useful for exporting files to Macromedia Flash or
Director, because both applications support this type of transparency.
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32-bit PNGs automatically contain transparency, though you won’t see a transparency
option for 32-bit PNGs in the Optimize panel.
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GIF images are exported without transparency by default in Fireworks. Even if the
canvas behind an image or object appears transparent in Original view in Fireworks, this
does not mean that the background for that image will be transparent when you export it
as a GIF for use on the web. You must select Index Transparency before export.
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Setting colors to transparent affects only the exported version of the image, not the
actual image. You can see what the exported image will look like in a preview. For
information about the document preview buttons, see
“Previewing and comparing
optimization settings” on page 334 .