1. A molecular-block-matching method for gel image analysis implemented in a medical system with one or more processors, said method comprising: (a) centering a first block on a first gel image at the location of a first protein spot; (b) centering a second block on a second gel image at an initial location corresponding to the location of said first protein spot on said first gel image; (c) shifting said second block by increments up to a maximum displacement from said initial location; (d) comparing the images within said first and second blocks prior to each incremental shift of said second block, in order to determine the closest matching second block to said first block; and (e) assigning the center location of said closest matching second block to a second protein spot on said second gel image.