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Accuracy of PSF representation in image restoration

Point spread function (PSF) models derived from physical optics provide more accurate representation of real blurs compared to the simpler models based on geometrical optics. However, the restorations obtained using the physical PSF models are not always significantly better than the restorations which employ the geometrical PSF models. The insensitivity of the restoration to the accuracy of the PSF representation is attributed to the coarse sampling of the recording device and insufficiently high signal-to-noise (SNR) levels. Low recording resolutions result in aliasing errors in the PSF and suboptimal restorations. In this work, a high resolution representation of the PSF where aliasing errors are minimized is used to obtain improved restorations. Our results indicate that the SNR is the parameter which ultimately limits the restoration quality and the need for an accurate PSF model. As a rule of thumb, the geometrical PSF may be used in place of the physical PSF without significant loss in the restoration quality when the SNR is less than 30 dB.