I checked Deep Zoom Composer, software that was used to create tiles [1]. It allows also PNG tiles export for "SeaDragon Ajax" output type, so it was probably

I checked Deep Zoom Composer, software that was used to create tiles [1]. It allows also PNG tiles export for "SeaDragon Ajax" output type, so it was probably just the decision of the author of this site to use JPGs. I tried to convert one randomly picked tile. It was 58KB JPG (16M colors), 38KB PNG (16M colors), 9KB PNG (256 colors), 13KB GIF (256 colors). So yes, PNGs would make a faster site and save some bandwidth. Though you cannot export 256 color PNGs, so for the best performance, you would need to run something like ImageMagick conversion script on all the tiles (with the danger of getting noticeable seams if neighboring palettes would clash). http://www.microsoft.com/downloads/details.aspx?familyid=457b17b7-52bf-4bda-87a3-fa8a4673f8bf&displaylang=en http://www.microsoft.com/downloads/details.aspx?familyid=457...