SAR Image Autofocus By Sharpness Optimization: A Theoretical Study

摘要: Synthetic aperture radar (SAR) autofocus techniques that optimize sharpness metrics can produce excellent restorations in comparison with conventional approaches. To help formalize the understanding of metric-based SAR methods, and to gain more insight into their performance, we present a theoretical analysis these using simple image models. Specifically, consider intensity-squared metric, dominant point-targets model, derive expressions for resulting objective function. We examine conditions under which perfectly focused models correspond stationary points A key contribution is demonstrate formally, specific case minimization autofocus, mechanism by methods utilize multichannel defocusing model enforce point property multiple columns. Furthermore, our shows function has special separble through it be well approximated locally sum 1-D functions each phase error component. This allows fast performance solving sequence optimization problems component simultaneously. Simulation results proposed actual imagery confirm extends realistic situations.