Imaging through the atmosphere from satellites: Restoration of images based on atmospheric MTF

The recently developed atmospheric Wiener filter, which corrects for turbulence and aerosol blur and path radiance simultaneously, is implemented in digital restoration of AVHR imagery over the five wavelength bands of the satellite instrumentation. Restoration is most impressive for higher optical depth situations which cause more blur, with improvement in regard to both smallness of size of resolvable detail and contrast. Turbulence modulation transfer function (MTF) is calculated from meteorological data. Aerosol MTF is consistent with optical depth, measured with a sum-photometer. The product of the two yields atmospheric MTF which is implemented in the atmospheric Wiener filter. Turbulence blur, aerosol blur, and path radiance contrast loss are all corrected simultaneously, as if there were no intervening atmosphere. Image restorations with accompanying atmospheric MTF curves are presented. However, restoration results using a simple inverse atmospheric MTF filter were quite similar. This indicates the satellite images were characterized by very low noise and that turbulence jitter was very limited which, in turn, indicates that the turbulence MTFs integrated upwards over the path length wee not significant when compared to aerosol MTFs. Restorations are shown for various wavelength bands and are quite apparent even under clear weather conditions.