Came across this. Possibly useful?
Cosmic?Ray Rejection by Laplacian Edge Detection
Author(s): Pieter G. van Dokkum
Source: Publications of the Astronomical Society of the Pacific, Vol. 113, No. 789 (November
2001), pp. 1420-1427
Published by: The University of Chicago Press on behalf of the Astronomical Society of the Pacific
Stable URL:
http://www.jstor.org/stable/10.1086/323894 .
Patrick
