A method and system for determining an optical waveform based on a plurality of print features of a selected marking of a document. The method and system comprise obtaining optical image data representing the print features of the selected marking. The optical image data is corrected for at least one of print contrast or reflectance of the print features in the optical image data using respective print contrast thresholds or reflectance thresholds to produce a converted pixel map of the selected marking, the pixel map containing an ordered sequence of values. Also included is a generation module to transform the print features represented in the converted pixel map to a plurality of corresponding waveform features to produce the optical waveform of the selected marking, the corresponding waveform features including a plurality of spaced apart peaks representing respective optical signal levels of the print features.