1. An apparatus for detecting concealed weapons disposed on a subject's body, the apparatus comprising: a millimeter wave camera having a field of view and operative to detect millimeter wave radiation within said field of view and further operative to provide a sequence of images from a plurality of different angles about the periphery of the subject's body; a image processing system, coupled to the millimeter wave camera, comprising: a spatial median filter for performing spatial median filtering on said sequence of images to provide filtered images, a 2-class segmentation filter for classifying pixels in the sequence of images, at least one median filter operative to receive one of a plurality of row evolution images and provide a median filtered row evolution image output, at least one valley identification modules operative to locate and identify ridges and valley edges in a corresponding one of said plurality of row evolution images, and wherein said image processing system is operative to: transform said sequence of images of the periphery of the body into a plurality of spatio temporal images formed by assembling together, for each specific row number, image rows with the specific row number in successive millimeter wave images in the original sequence, said plurality of spatio temporal images corresponding to a plurality of row evolution images, classify said plurality of row evolution image according to its location within the body's image, identify an object of a class of preselected objects as a function of the identified and calculated strength of valley edges and the identified and calculated strength of ridges in said plurality of row evolution image; and provide an output indicative of an identified object.