27 – Video signal processing

Publisher Summary This chapter mentions several diverse topics concerning the representation and processing of video signals. It informs that it is necessary to avoid an instantaneous transition from blanking to picture at the start of a line. It is also necessary to avoid an instantaneous transition from picture to blanking at the end of a line. The chapter recommends that the first luma (Y') sample of a line should be black, and that this sample should be followed by three transition samples clipped to 10%, 50%, and 90% of the full signal amplitude. It suggests that transition values should be applied by clipping, rather than by multiplication, to avoid disturbing the transition samples of a signal that already has a proper blanking transition. The chapter also analyzes the Chroma transition improvement (CTI) technique and Scan-velocity modulation (SVM). The multiplication of foreground and background data in keying is equivalent to modulation. This can produce signal components above half the sampling rate, thereby producing alias components.