A fast implementation method for the FFBP algorithm

A fast implementation method for the fast factorized back-projection (FIM-FFBP) algorithm is proposed to focus high-resolution spotlight synthetic aperture radar (SAR) data. Different from the original FFBP utilizing two-dimensional image-domain interpolation for sub-aperture fusion, FIM-FFBP finishes the image fusion using chirp-z transform and circular shifting. FIM-FFBP yields enhanced efficiency over the nearest interpolation with 4 times upsampling based FFBP, and keeps the high precision simultaneously. Real-data experiment verifies the efficiency superiorities of the FIM-FFBP.