Cover images for PML/PDB -- size?

[Jon Noring]

I am now converting the e-book I have published for umpteen years into: 1) PDB for eReader (targeting the iPhone), 2) Kindle (I'll be using DTP), and, of course, 3) ePub (hey, I co-authored the specs! )

My simple question now relates to the cover image used in PDB files for eReader.

Specifically, I would like to verify from the long-time pros here that indeed the cover image, and any image used in the document, needs to be a 256-color (8-bit) PNG file with maximum dimensions of 158 pixels wide and 148 pixels high. (I know there is also a maximum file size of 65505 bytes, usually easily achievable for this max pixel size and color depth.)

If this is not correct, what are the requirements, especially with regards to optimization for the iPhone?

Thanks!