The restoration of extended astronomical images using the spatially-variant point spread function

In this paper we address the problem of image restoration of extended astronomical objects, where the effects of inhomogeneous random media, such as atmospheric turbulence, result in distortion over the pupil plane. Distortions are usually expressed in terms of the point spread function (PSF) and can be used to restore an image with the application of a deconvolution algorithm. Since the PSF is generally spatially dependent, restoration of extended images within specific homogeneous (isoplanatic) regions is required. Inconsistencies at the borders of each region result in error boundaries between restored isoplanatic regions and the object. To minimise such distortion, we determine the optimal size of each isoplanatic region and then apply a linear filter to estimate the PSF between boundaries.