VIDEO SIGNAL PROCESSING

摘要

In a system for detecting scratches in video material originating from film material (,) values of amplitude derivatives are measured to provide local and background activity levels, and the difference between these values is formed. If the magnitude of the difference is positive and smaller than a given value (,) the value of the difference is accumulated vertically. The accumulated value is compared with a threshold to detect a scratch. Accumulation also takes place over fields. The polarity of the local activity level is carried forward to identify a detected scratch as dark or light for use in subsequent concealment processes.