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Summary

Two problems related to WF/PC imagery have been addressed: restoration in the presence of undersampling and restoration in the presence of a space-variant point-spread function.

It has been argued that the process of Richardson-Lucy (RL) restoration with subsampling is not fully understood in the presence of undersampling and that further work is required. A POCS-based variant of the RL-algorithm with subsampling has been suggested for further examination. Also an alternative model-based algorithm for detecting irregular random missing data such as cosmic ray (CR) hits has been proposed. The algorithm is based on a spatially adaptive, dynamic - clipping, which should be optimal, at least for single-pixel CR-hits.

A novel, easily parallelizable algorithm for faithful image rotation has been stated. It is based on a sequence of three successive shears which in turn can efficiently be implemented using fast Fourier transforms (FFTs). The rotation algorithm is required within a joint restoration of multiple rotated WF/PC frames.

Finally a novel algorithm has been proposed for restoring full-frame WF/PC images distorted by a space-variant point spread function (SV-PSF). The algorithm is efficient and parallelizable. The algorithm allows several interesting generalizations which promise to either increase performance or restoration quality or both.

With these algorithms a comprehensive full-frame SV-PSF restoration of single or multiple WF/PC frames now appears to be feasible.


rlw@sundog.stsci.edu
Fri Apr 15 15:48:04 EDT 1994