When reading about this I came up with the idea of rendering a JPEG on a canvas element with a PNG (or grayscale JPEG) as a transparency map. This would give yo

When reading about this I came up with the idea of rendering a JPEG on a canvas element with a PNG (or grayscale JPEG) as a transparency map. This would give you alpha-channel JPEG on most browsers right now. Sweet huh? ... and of course, it's been done: http://jim.studt.net/jpeg-alpha/ http://jim.studt.net/jpeg-alpha/ :) It's even been on Hacker News, though not to much attention: http://news.ycombinator.com/item?id=1772760 http://news.ycombinator.com/item?id=1772760