PNG8 vs other image formats
PNG8 is a rising winner in all the battles between the web formats. It has smaller size than GIF and PNG24, it has alpha channel, and the really big advantage is the semi transparency, which unfortunately degrade in IE6 to a GIF-like full transparency. So there are few very important advantages at all:
1. smaller size than PNG24 and GIF
2. same semi-transparent pixels as PNG24 but with smaller size and no need of alpha filter for IE6, where there’s a GIF like full transparency.
Fireworks and semi transparent pixels in PNG8
The problem is that only Adobe (former Macromedia) Fireworks can export such semi transparent PNG8s, and it’s not free. You may guess PNG (Portable Network Graphics) is a Macromedia format which unfortunately turns into closed capability of rendering PNG8 with transparency and with no need of Fireworks. Very sad!
Finally these days I found a workaround with PNG8 and it’s called pngquant. You can find the tutorial on http://www.ethanandjamie.com/blog/37-user-interface/81-png8-transparency-without-fireworks and everything here’s about the above pngquant.
Now make your website sprites