Enhancements to a video anticopying process that causes an abnormally low
amplitude video signal to be recorded on an illegal copy. The enhancements
in one version introduce into the overscan portion of the television
picture, just prior to the horizontal or vertical sync signals but in
active video, a negative going waveform that appears to the television
receiver or videotape recorder to be a sync signal, thereby causing an
early horizontal or vertical retrace. One version provides (in the right
overscan portion of the picture), a checker pattern of alternating gray
and black areas which causes the TV set on which the illegal copy is
played to horizontally retrace earlier than normal in selected lines with
a consequential horizontal shift of the picture information on those
lines. This substantially degrades picture viewability. In another version
a gray pattern at the bottom overscan portion of the picture causes
vertical picture instability. In another version selected horizontal sync
signals are narrowed, causing irregular vertical retraces. Also provided
is apparatus for removing or attenuating these enhancements from the video
signal, to allow copying.