Providing an accurate tally indication of sources in use for output

摘要

In the processing of digital video signals there is provided in association with each signal an accompanying tally signal which provides an instantaneous identification of one or more signal sources from which the information contained in each pixel of a picture image has originated. The format of the tally signal may enable processing thereof to identify all signal sources contributing to a particular image area, to pixels of a mixed image or to any given field or frame of a video image signal. The signal may be encoded in the format of the digital chrominance signal component of a color picture signal and combined with a conventional key signal which is encoded in the format of a digital luminance signal so that the combined signal has the format of a color picture signal.