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Tomographic methods for the restoration of LBT images
M.Bertero, P.Boccacci, S.Correia, A.Richichi
Interferometry in Optical Astronomy - Proc. SPIE Vol. 4006, 514-522 (2000)
The Large Binocular Telescope (LBT) has been designed for providing images with high sensitivity and resolution by means of optical/infrared interferometry. It will require specific methods for data reduction since the image of an astronomical object will be obtained from a set of interferometric images corresponding to different orientations of the baseline. In this paper we first stress an interesting analogy between the images of LBT and the projections in Computed tomography (CT). Next we use this analogy for extending to LBT some iterative restoration methods developed for CT, such as ML-EM (Maximum Likelihood -Expectation Maximization), its accelerated version OS-EM (Ordered Subset - Expectation Maximization) and the improved version RAMLA (Row-Action Maximum Likelihood Algorithm). These iterative methods approximate solutions of the Maximum Likelihood problem in the case of Poisson noise. We also consider iterative methods which have been proposed for solving the same problem in the case of Gaussian noise, in particular the Iterative Space Recostruction Algortithm (ISRA) and the Projected Landweber (PL) method. All these methods are implemented and tested by means of same simulated LBT images.