Given an array (being it a signal or an image), with this mini toolbox it is possible to calculate the normalized number of occurrences of the first digit and to compare it with the Benford's Law. Any signal can be classified into four degrees of conformity to the Benford's Law (close conformity, acceptable conformity, marginal conformity and non conformity). Test it with your data! It can help in detecting frauds, since most of natural phenomena are expected to be close conform to Benfords' Law. When the test says that they are not, it might mean that the data has been manipulated!
More references
This wikipedia page: https://en.wikipedia.org/wiki/Benford%27s_law
This Wiley book: http://eu.wiley.com/WileyCDA/WileyTitle/productCd-1118152859.html
(M Nigrini & JT Wells, Benford's Law: Applications for Forensic Accounting, Auditing, and Fraud Detection, 2012)