NB!  In contrary to conventional approaches, which exploit a (unique) point of entropy maximum,
we seek  one of   minimum points:  minimization  of entropy without  proper constrains is meaningless.
See : Page # 20: Gateaux derivative of entropy

An example of more "cool" implementation of the Entropy of Image Contrast:
An inverse problem of a source location 
( EnIC & snapshots of seismic source images )