Digitization and calculation on video pictures were accomplished in real time. Video pictures were subtracted and added in order to achieve an enhanced difference picture. The number n of video frames varied from 2 to 2048. Enhancement of signal-to-noise (S/N) ratio went nearly as VII, and S/N ratios of 1700:1 were obtained in about 1 min. A new design is presented to raise the digitizing rate from the present 180 kHz to 2.4 MHz in order to improve resolution. The application is to the measurement of solar magnetic fields, which are proportional to small differences between solar pictures of opposite polarization. A sensitivity increase of NTri and real time display will provide a possible solar flare warning system. Other applications are mentioned.
Thomas J. Janssesn,
Gregory C. Kozlowski,
"Real Time Digital Subtraction and Enhancement of Video Pictures," Optical Engineering 6(4), 604120 (1 May 1968). https://doi.org/10.1117/12.7971386