Duncan Davidson on using Progressive JPEGs to better serve hi-res photos to the new iPad:
Last night a group of tweeps, including Steve Streza, collaborated with me to track down a limit in WebKit on the iPad when working with large JPEG files. After reverse engineering the limits and then later being pointed to the documentation about the limits, somebody suggested using a progressive JPEG file based on the observation that the large iPad hero image Apple uses is a progressive JPEG. I’ve not used progressive JPEGs in years, but following that suggestion, I gave it a shot. Lo and behold, it’s indeed the ticket to large JPEG joy on the iPad Retina display.