An imaging system includes a platform having mounted thereon a coded-aperture imaging device and positioned to receive radiation over a baseline. The imaging system includes a computer configured to acquire a plurality of far-field datasets over the baseline, the plurality of far-field datasets comprising data received via the coded-aperture imaging device. The computer is also configured to form a preliminary image based on the acquired plurality of far-field datasets, and apply an expectation maximization (EM) algorithm to the preliminary image; wherein the EM algorithm includes an ordered subset algorithm.