I have hundreds images that will be loaded and displayed randomally and then change to another image (there are 4 image boxes, each one displays a specific image for 10 seconds and then changes to another completely random image.)

Now these images need to be rounded, however I've tried every possible method I can think of.
I can't use a transparent image to place over the image with rounded corners because the background is stretched (a liquid template).

I've tried javascript rounded image corners (js corners) (doesn't work with image transition and too much delay), tried to use an image to place overtop (looks horrible), css rounded corners (needs to be more cross browser). The only method I can think of is PHP, however that is really CPU intensive and there will be a lot of images.

I'm looking for some ideas, maybe different background image and positioning for each resolution instead of a single stretched background? But I'd much rather not double the loading time.

Any ideas?

* Steve