A simple method for the reduction of boundary effects in the Richardson-Lucy approach to image deconvolution

In this paper we propose a solution to the problem of reducing the boundary effects (ripples) in the deconvolution of astronomical images. The approach applies to the Richardson-Lucy method (RLM), namely the most frequently used deconvolution method in Astronomy, and is based on the idea of using RLM for attempting a reconstruction of the astronomical target in a domain broader than that of the detected image. Even if, in general, the reconstruction outside the image domain is not reliable, this approach, in a sense, is letting RLM to choose the appropriate boundary conditions and, as a consequence, the reconstruction inside the domain is considerably improved. We propose a simple implementation of this approach, allowing a reduction of its computational burden. Numerical experiments indicate that it is possible to obtain excellent results. Extensions and applications of the method are briefly discussed.