This paper discusses a multistage approach to entropy minimization for SAR image autofocus. The new algorithm is compared to existing approaches, including point based autofocus, sub-aperture based autofocus, and hybrid methods. Monte Carlo statistical results are presented for simulated clutter scenes and point target scenes. The new minimum entropy autofocus provides improved speed and accuracy in correcting azimuth phase errors in both scenarios.
Brian D. Rigling, Brian D. Rigling,
"Multistage entropy minimization for SAR image autofocus", Proc. SPIE 6237, Algorithms for Synthetic Aperture Radar Imagery XIII, 62370J (17 May 2006); doi: 10.1117/12.669957; https://doi.org/10.1117/12.669957