Minimum entropy autofocus correction of residual range cell migration

摘要

In this article, we present a SAR autofocus algorithm that can correct for motion errors exceeding a range-resolution cell. Most traditional autofocus algorithms operate by applying a 1D phase correction in the cross-range dimension of the image spatial frequency domain [1]-[3]. When the motion errors exceed a range-resolution cell, 1D phase-only compensation is not sufficient. We will describe an algorithm that can deal with such errors by using a 2D phase correction. Our algorithm is based on optimizing image focus by minimizing the image entropy.