guess-sig(1)
Forensics utility to help identify file signatures of undocumented and proprietary binary formats.
guess-sig /path/to/files/*
Its output looks like this:
FF D8 FF E0 00 10 4A 46 49 46 00 01 01 __ 00 __
00 __ 00 00 FF __ 00 __ __ __ __ __ __ __ __ __
See the program's manpage for options and usage examples:
man guess-sig