What colour depth should I use

When I build for the Ipad target in Unity the graphics that end up on the
iPad screen are very poor quality compared to the original graphic I used in the
Unity object. Can anyone tell me what colour depth and format I should be using
to create the original artwork to get best results on the actual hardware?

Also does anyone know what the iPads colour depth and format actually is as I can’t find
the answer anywhere on the internet.
Thanks.

Check this out:
http://unity3d.com/support/documentation/Manual/Textures.html
There is an iOS section you need to open up, but look for “Texture Format”.

Generally you should probably use PVRTC format of 4 bits, but you might be able to use the DXT5 format.
Problem is DXT5 format will be too big if you need many images.
As it says, PVRTC formats give you sufficient results in much smaller sizes…