aimage (the advanced imager) is an imaging tool which is part of AFF, the 
Advanced Forensic Format.

aimage can create files in raw, AFF, AFD, or AFM formats. AFF and AFD 
formats can be compressed or uncompressed. aimage can optionally compress 
and calculate MD5 or SHA-1 hash residues while the data is being copied. 
It has intelligent error recovery, similar to what is in ddrescue. 

aimage requires afflib, which is also available at at SlackBuilds.org.
