iPad stack file size and image pixellation

[yeldarb]

So I'm doing a mobile app that's some classic clocks. I want it to work nicely on the iPad, so the stack size is 768 x 1024.

I did the clock images as 1536 x 2048 PNGs, then scaled them by 1/2 in the stack, and set the resizeQuality to best. My thinking was that when they scaled up on the ipad they wouldn't be pixellated.

However, I discovered two things:

1. Even though the image is actually 1536 x 2048, it's still quite pixellated on the ipad, and
2. The 24 bit uncompressed PNGs make my stack HUGE (for a mobile app) -- 77MB.

I think I can solve the first issue by making the stack's native size 1536 x 2048.

I'm using PNGs because I've got an alpha channel so the user can set the clock's background color. I can use JPEGs but I won't be able to have transparency.

Are there any simple solutions to overcome these issues?

[yeldarb]

Ok, I just came across a thread about referenced (2x) images, so that should work for the ipad. However, that means an even LARGER file, since I apparently need both a 1x and 2x version...