A short while ago "Ty W" posted an interesting question on StackOverflow. Apparently, most graphics software cannot scale images the right way. Usually it's hard to notice the flaw but the linked article does a great job of explaining the problem. PHP's GD library suffers from the same issue, but Ty discovered that the sample PHP program provided with the article did not work on partially transparent images. After a couple of hours of fiddling I managed to get a working solution.