Use SD and HD Atlas

[ilovebird]

Hi, everyone. I'm a NGUI beginner.
I want to use SD Atlas on iPhone3GS or earlier devices, and to use HD Atlas on retina devices, I've already known how to switch SD and HD by reference, but the actual fact is not right, how should I do?
The UIAtlas-Coordinates should be Pixels or Tex Coords? and Pixel Size in HD Atlas should be 1 or 0.5?
and UIRoot-Manual Height should be 480 or 960? (Portrait)
Thank you.

[ilovebird]

I then force it to use HD Atlas, and in Unity Game window(640*960), it works fine, but on my retina device - itouch4, it still looks SD Atlas, any one know why? Thanks!

[ilovebird]

I find the answer, the Atlas is too large, so it doesn't work.