I using Unity3D 3.0 ver now.But compare with Unity3D 2.6 ver this version import PNG files have some problem.
1.I want import a PNG file. This file size is 30*414 but when the Unity3D imported it,it will be show the size change to the 32*512 in the Preview in the Unity3D 3.0 ver. In the Widnows and in the Photoshop the size still 30*414.I don't know why the Unity3D to change the size.
2.Sometimes Unity3D 3.0 Load the PNG Alpha is incorrect. The PNG file is include the Alpha.We are use the same way to make the PNG files and same exports from Photoshop.In the Unity3D 2.6 ver these PNG files Alpha are correct. But in the Unity3D 3.0 ver are incorrect.
Unity is automatically converting your textures to dimensions that are a power of two (i.ee 2, 4, 8, 16, 32, 64, 128, 256, 512, 1024, etc).
Unity 3.0 has slightly different behaviour for importing non-power-of-two (NPOT) textures compared with earlier versions, and its behaviour in this regard is described in detail on this page:
As for the "incorrect" alpha channel import, you will have to give more detail about what in particular is incorrect. Just stating "incorrect" does not provide us with enough information to be able to help you.
We are developing iOS (iPad) game and on some textures that were exported as transparent png alphas (24bit from Photoshop), in game some button graphics have small lines and graphics errors placed at top or bottom of texture. When reimport the same gfx used in game, Photoshop does not show any graphics incorrections. Those parts of the graphics has nothing in it… I can show you snapshooted examples and original png image we used for the game.