The success of HST image restoration depends critically on the ability to obtain, either through direct observation or through detailed optical modeling, a good estimate of the point spread function. PSF models are, in principle, superior to observed PSFs owing to the lack of noise and the ability to compute the PSF on a higher density pixel grid. We describe an approach to PSF modeling for the HST which utilizes two complementary programs: (1) a sophisticated prescription retrieval code, and (2) a hybrid PSF modeling code that combines both ray-tracing and diffraction propagators. The PSF modeling code will be made available to the HST user community through the ST ScI.
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