A digital system can handle tasks ranging from the simple enhancement of contrasts and contours to the advanced restoration of blurred texts. When combined with a sophisticated physical imaging system, an image processing system has proven to be a powerful and fast tool for the routine, nondestructive scanning of suspect documents. Applications include techniques to increase legibility; two-dimensional spectroscopy focusing on ink discrimination, alterations, or erased entries; comparison techniques for examining stamps, typescript letters, and photo substitution; and densitometry. The system provides results within seconds or minutes. It can also be linked directly to devices like video spectral scanners and microscopes. The available budget will determine whether the system uses a low-cost personal computer or an advanced image processing. Figures and 52 references. (Author summary modified)