IMPLEMENTATION OF A MODIFIED RICHARDSON-LUCY METHOD FOR IMAGE-RESTORATION ON A MASSIVELY-PARALLEL COMPUTER TO COMPENSATE FOR SPACE-VARIANT POINT-SPREAD OF A CHARGE-COUPLED-DEVICE CAMERA

Several imaging devices are characterized by a space-variant point-spr ead function (PSF), such as the wide-field/planetary camera of the Hub ble Space Telescope (HST). Several techniques for image recovery that use data from such imagers approximate the space-variant PSF by a spac e-invariant PSF. A modified Richardson-Lucy method is implemented that accommodates the space-variant PSF of the HST as well as corrections for background counts, nonuniform flat field, and readout noise. The i mplementation runs on the DEC mpp 12000 Sx/Model 200 massively paralle l computer. Restorations of simulated HST images are obtained with a s pace-variant PSF and, for comparison, with a space-invariant approxima tion. Results of these processing methods are compared, and it is foun d that a residual artifact appears in restorations when a space-invari ant PSF is used owing to the mismatch of the PSF kernel used in the re storation and the space-variant one underlying the image acquired with the telescope. This residual artifact is effectively eliminated when the processing is based on the space-variant PSF. (C) 1995 Optical Soc iety of America