Quote Originally Posted by Harrison View Post
Actually that is a misunderstood thing about PNG. It actually supports both lossless and lossy formats, and allows the saving of up to 256 colour lossless images with transparency, or up to full colour 24bit lossy images, all within the single format. Therefore it is really the only format that would be needed for anything online if only it was supported by every browser.
Really? I thought (and from experience have always found) it to be a lossless compression at both 256 and 24bit.

Edit: Just checked it's Wikipedia page - no mention of it being lossy. Also did a test - a 1.17MB 24bit BMP file, shrunk to a 129KB 24bit PNG file. The same BMP file when added to a zip file compressed to 115KB (zip of course is lossless compression). Therefore as there is less that 15KB difference, I believe that PNG is also lossless.

Edit2: I'm now convinced you're wrong Harrison! I found the official specification for PNG. Quote: "There is no lossy compression in PNG. Existing formats such as JFIF already handle lossy compression well. Furthermore, available lossy compression methods (e.g., JPEG) are far from foolproof --- a poor choice of quality level can ruin an image. To avoid user confusion and unintentional loss of information, we feel it is best to keep lossy and lossless formats strictly separate."