Selective edge softening and selective edge dithering is introduced into an image representation to improve local control where halo problems are expected. The AC and DC responses are measured; a corrected DC response is determined using the AC response; and a concentration of the analyte is determined based upon the corrected DC response. The first and second parts are secured together, repairing the defect. Measurement and analysis of these parameters, and others, provides details regarding the vascular health of individual and multiple vessels and a global analysis of an individual’s overall vascular health.