1. Optical image subtraction;Ebersole;Opt. Eng.,1975
2. “Optical image subtraction techniques, 1975-1985”;Liu;Proc. SPIE 0638, Hybrid image processing,1986
3. Grid code: A technique for extraction of differences from scenes;Pennington;Opt. Commun.,1970
4. Subtraction (or addition) of illuminance;Belvaux;Proc. ICO-IX,1972
5. Image subtraction by polarization-shifted periodic carrier;Daschiell;Opt. Commun.,1973