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A Digital Telecine Processing Channel

1979; Society of Motion Picture and Television Engineers; Volume: 88; Issue: 7 Linguagem: Inglês

10.5594/j06638

0036-1682

A. Oliphant, M. Weston,

Embedded Systems Design Techniques

Digital processing of signals has advantages of improved stability, accuracy, and reliability. There are two problems that might arise in a digital processing channel. One is that gamma correction increases the visibility of contouring due to quantizing in dark areas of the picture so that more than the usual eight bits per sample are needed. The other is that nonlinear processing in gamma correctors and clippers may give rise to beats causing coarse moire patterns on the output picture. A digital telecine processing channel was built to examine these problems. It incorporates a range-changing analog-to-digital converter which gives improved coding resolution for low level signals. The channel performs the operations of gamma correction, color masking, and aperture correction. A subjective test has shown that ten bits per sample are needed in the green channel when signals are digitally coded before gamma correction. The generation of moire patterns due to nonlinear processing has been shown not to be significant in practice.