... To address the problem of point-source photometry in restored images Lucy (1994) suggested a two-channel photometric restoration method in which the points are represented as functions in one channel and the background, constrained to be smooth by an additional entropy constraint, in the other. ... In the new CPLUCY implementation the stars can be at arbitrary x , y sub-pixel positions but the entropy constraint on the background, used by PLUCY, is retained. ...