[mark-r]

The problem is coming up with a scaling algorithm that works ideally on every kind of image; it simply can't be done. Some methods work better for some images, and other methods work better on others. Wikipedia has a good overview: http://en.wikipedia.org/wiki/Image_scaling

The scaling in the browser has to work on any arbitrary resizing, not just 2x. A simple pixel doubling only works in one specific circumstance, and would be inconsistent with other scaled images.

[eltados]

Thank you very much, execellent read. I still think / hope that there is room for apple to improve the way they do their image scaling in iOS for the retina display. I think it is not sustenable to expect all the web to support high res images everywhere in the short to medium future.