Application of the OS-EM method to the restoration of LBT images

¹ INFM and DISI, Universitá di Genova, Via Dodecaneso 35, I-16146 Genova, Italy
² INFM and DIFI, Universitá di Genova, Via Dodecaneso 33, I-16146 Genova, Italy

Send offprint request to: M. Bertero, e-mail: bertero@disi.unige.it

Received: 13 October 1999
Accepted: 17 February 2000

Abstract

The Large Binocular Telescope (LBT), which will be available in a few years from now, has been designed for high-resolution optical/infrared imaging through coherent cophasing of the two mirrors. The structure of the process of image formation in LBT is similar to that in Computed Tomography (CT) so that it is interesting to investigate the applicability to LBT of image restoration methods developed for CT. A powerful one is the so-called Expectation Maximization (EM), which is also known in the astronomical literature as Lucy-Richardson (LR) method. However slow convergence is a drawback of this method. In the case of CT an accelerated version, based on ordered subsets of projection data (OS-EM), has been proposed. In this paper we adapt OS-EM to the problem of restoring LBT images and we show that it provides an acceleration by a factor which is roughly equal to the number of independent interferometric images of the same object.