Brightness intensity fault correction for film scanning appts. - detects analog system caused faults contg. output signal of photo-multiplying stage

摘要

The automatic brightness intensity fault correction is used in film scanning appts. with a cathode ray scanner. In the process an analogue output signal of a photomultiplying stage (1), the system-related faults is detected and converted into a digital signal. The latter is stored in a memory (5), a correction signal is generated, and read-out from the memory during scanning synchronously with the scanning system. It is then converted into an analogue signal and supplied to a video channel (2) for arithmetic adding to the output signal of the photomultiplier stage. Pref. the correction signal compensates brightness variations of the CRT scanning beam or irregularities of the phosphor. ADVANTAGE - Entire colour spectrum correction without extra appts.