• Reported by Nate

If AOL adopts Mozilla as it's default embedded browser, we may get a workaround to AOL's sneaky image caching and re-compression and it's associated problems.
First a little background info: AOL uses it's own proprietary (".art" format) compression technique (developed by Johnson-Grace) to recompress and cache images before they are delivered to AOL subcribers. This introduces the following issues for us web designers - it is difficult to predict (many images show no ill effects), sometimes very ugly, and completely unavoidable. I should probably say "completely unavoidable unless your image is less than 1k, or you hold an AOL partner status", which I hear entitles you to a top secret development tool which can handle the ART format - no comercially available image editor will open or save in the ART format, not even Photoshop.
As long as AOL does not add the PNG format to their list of compressable/cacheable items, we could deliver PNGs to get around the problem - Mozilla supports them. I'm not certain on this, but it might even be possible to use css to filter png images to mozilla based browsers.
More info on the reasons for these compression issues, webreference also has more info near the bottom of this page about graphics formats.
Several years ago I ran into this issue with a site design created for a client who viewed the work from his home AOL connection. From my personal experience I'd like share a tip for combating undesireable results (massive resampling of a greyscale gradient in my case): save JPGs as progressive and use trial and error with the progressive settings. Hopefully my little snippet of advice will save someone the 3 days it took me to figure it out.