A segmentation method of a frame of image information including a plurality of spaced DNA spot images corresponding to a plurality of DNA spots. The image information includes image intensity level information corresponding to said DNA spots. A grid including a plurality of spaced grid points corresponding to selected DNA spot images is generated, such that each grid point includes position information indicating the position of the grid point within said frame. For each DNA spot image: (1) background and signal intensity levels are extracted from image characteristic values for the spot image, and (2) difference values between the background intensity levels and signal intensity levels are determined. For each DNA spot: (1) the corresponding difference values are related a range of graphic values, (2) a graphic value for each difference value is selected; and (3) the selected graphic values are displayed.