[thelist] 8-bit PNGs with full transparency?

Francois Jordaan francois.jordaan at wheel.co.uk
Thu Aug 1 10:40:01 CDT 2002


Why can Fireworks export 8-bit PNGs with smooth 8-bit transparency, while
Photoshop (I'm using version 6) only allows this with 24-bit PNGs? As far as
I can tell it's in the PNG spec:

http://www.webtechniques.com/archives/1997/10/desi/
"Actually, PNG also supports 8-bit palette images, just like GIF -- and it
supports transparency for these images better than GIF does: The artist can
set the level of transparency for every color in the palette. If you want to
have four identical versions of red, except with different levels of
transparency, you can go right ahead and do that. " -- Tom Boutell

This is an incredibly useful feature, as 24-bit PNGs of course have *much*
larger file sizes than 8-bit ones. I don't know about browser support for
8-bit transparent PNGs, but they're fully supported in Flash (which is what
I need them for.)

Is there a plug-in for Photoshop that does a proper job, or do I have to
stick to Fireworks?

francois

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