Abstract : The goal of this project is to formulate and investigate new approaches for forming images of radar targets from spotlight-mode, delay-doppler measurements. These measurements could be acquired with a high-resolution radar-imaging system operating with an optical- or radio-frequency carrier. Two approaches are under study. The first is motivated by an image-reconstruction algorithm used in radionuclide imaging called the confidence-weighted algorithm; here, we will refer to this approach as the chirp-rate modulation approach. The second approach is based on more fundamental principles which starts with a mathematical model that accurately describes the physics of an imaging radar-system and then uses statistical-estimation theory with this model to derive processing algorithms; we will refer to this as the estimation-theory approach. Spotlight-mode high-resolution radar-imaging relies upon the relative motion between the transmitter, target, and receiver. The target is illuminated by a series of transmitted pulses. The return for each pulse is a superposition of reflections from various locations on the target, with each location affecting the pulse by introducing a time delay, doppler shift, and reflectance gain. The returns are processed to produce an image of the target. Two types of images are possible. One is a map in delay/doppler or range/cross-range coordinates of the target's complex-valued reflectivity, which indicates the amplitude-gain applied to the incident radar-pulse by each location on the target. The other is a map in the same coordinates of the target's scattering function, which indicates the power-gain applied at each location on the target.