The RLG Working Group which suggests using 16 elements to capture crucial information about a digital file, their elements are fairly 'lightweight' and would probably be OK assuming that some descriptive metadata (e.g. DCMES) is also available. It's a bit old now, and it might be worth looking at METS or the more detailed set of elements which can be found in the draft NISO Technical Metadata for Digital Still Images standard.
You could also have a look at the OCLC/RLG Preservation Metadata Working Group which has published an overview (chiefly of the OAIS model, and the specifications developed by Cedars, NEDLIB and NLA) and recommendations for 'Content Information' and a forthcoming one on 'Preservation Description Information'. Or there is OCLC's own preservation metadata set.