Here is an excerpt from the Primer, written by Larry Daniel, a computer forensic expert available for hire as a defense expert:
Here are the different kinds of formats you can expect to see in cases and how to deal with them.
1. Encase format or as it is also known, Expert Witness format or E01 format. Encase by Guidance Software, Inc.
1. This is the “native” format for creating copies of digital evidence when the copies are made using Encase Forensic software. The file extension for these files begin with .e01 and are numbered .e02, .e03 and so on.
2. FTK format. FTK, which stands for Forensic Tool Kit, is a forensic software by Access Data Corporation. It is the second most popular forensic software in use by law enforcement in the US.
3. DD aka RAW format. DD format can be created by several different programs and hardware devices used to create forensic copies of hard drives and other digital media. It is an open source format and is commonly created using the Linux dd command.