Pet Pixels

I just came across this neat trick for providing custom icons (think favicon.ico, but with a reasonable size, better colour and a proper file format) for web pages for iPhone/iPod touch users. There seemed to be some debate over what exactly the native size is, so I built a test page to test it. The full-size icon image is also displayed on the page, but that's only there to show what the phone is starting with. After twiddling with this test for a while, I came to the conclusion that there isn't a native size - it's somewhere between 59x59 and 60x60 - though 60x60 is about as close as you can get. This lack of native size is interesting, as it implies that the iPhone UI is using resolution independent rendering, which we know OS X can do. Bigger sizes do scale more smoothly, but they're a waste of bandwidth and mean that you lose control of the exact appearance - photographic icons will look very nice, but anything involving single pixels lines will probably suffer badly. If you're a pixel geek that doesn't like your images twiddled with and you've painstakingly created your icon in Photoshop, you need to know the native size. If anyone finds a perfect image size (which may well not be square), please leave a comment.