Coming from the mighty Fireworks, I'm used to exporting PNG-8 files with alpha transparency - for many graphics, it's PNG24 quality using less bytes.
But I can't see how to do this in Illustrator. There's only a checkbox for Transparency, not the None/Index/Alpha options present in Fireworks. See below:
Is it possible to export a PNG-8 with alpha transparency from Illustrator, or can only Fireworks do this?
Go to File -> Save For Web.
A dialog box will appear displaying the original artwork on one side and what will be saved out on the other (a preview). On the far right are the settings.
In these settings, select PNG-8 from the format dropdown and configure the PNG-8 settings to your liking (transparency, color table, matte color, color reduction algorithm, etc.)
Then click save and you'll have exported a PNG-8 version of your artwork. PNG-8 only allows for 255 colors though (including transparency) so plan your artwork accordingly.
Exporting 8-bit pngs with alpha transparency is not possible in Illustrator.
Alpha transparency means pixels may be partially transparent (each one has an alpha channel controlling it's opacity). Only complete transparency is allowed for pixels in 8-bit pngs – it's equivalent to Fireworks' "index" transparency.
You can set a "transparency dither" on 8-but png's in Illustrator, where it mixes completely transparent and completely opaque pixels together. This is not very useful.
24-bit pngs work fine... as long as you don't mind them being 3x the size! My workflow is to export 24-bit png's from Illustrator, then compress them to 8-bit in good ol' Fireworks CS5.
