1. A two-dimensional prominent point processing method used in a synthetic aperture radar (SAR) system for removing a two-dimensional phase error in a complex image, the method comprising: generating the complex image with a sensor; identifying a good quality unfocused isolated point target within the complex image; cropping a target and an immediate area surrounding the target; taking a two-dimensional inverse Fast Fourier Transform (FFT) to obtain a phase history; and taking a two-dimensional phase from the phase history of the cropped target as a measurement of the two-dimensional phase error on the image.