I've create an atlas with NGUI's Atlas Maker, the result is an 2048x1024 automatic truecolor 8M image. So far so good.
As long it's taking too much from my memory, and as long it's just pictures (no text or anything that has to be pixel perfect) I decided to compress it.
When I do, it becomes an 2048x2048 image and saves me 6M, great.
The problem is that at this point, all the atlas coordinates are wrong.
What can I do to fix it keeping my texture compressed?