Image processing is an increasingly important aspect for analysis of data from X and γ-ray astrophysics missions. In this paper, I review a method proposed by Kebede (L. W. Kebede 1994, ApJ, 423, 878), and point out an error in the derivation of this method. It turns out that this error is not debilitating – the method still " works " in some sense – but as published is rather sub-optimal, as d...