hCheck estimates, using mathematical methods, the 0th to 4th order entropy of any given input file. Entropy is a measure for the theoretically possible compression on a given stream of data, for more info please refer to Wikipedia. hCheck displays all relevant information on screen, but it it can also write a Excel/OpenOffice.Org compatible CSV file.

Download it from here:
hCheck v2.0 (BSD)

You may freely use hCheck and the included source code under the terms of the BSD. It is also included in my JPEG Open Source Developers Package.