1. A method for enhancing resolution of an image, said method comprising: providing a range-Doppler image of at least one cluster; applying a two-dimensional (2-D) band-pass filter to said range-Doppler image to produce a modified image; applying a constraint on concavity to said modified image to produce a mask image; and applying said mask image to said range-Doppler image to produce a resolved image, wherein said applying 2-D band-pass filter comprises applying a smoothing filter and applying a differentiating filter.