1. A method for generating an optical waveform based on a plurality of print features of a selected marking of a document, the method comprising the steps of: obtaining optical image data representing the print features of the selected marking; transforming the print features represented in the optical image data 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, the waveform features used further including at least one of the features of: peak spacing between adjacent peaks; a reference value between peaks representing a lack of the printed features; selecting only positive peaks; selecting only negative peaks; or selecting both positive and negative peaks.