Abstract: Copy protection for composite video signals is well known. Copy protection, while it does not prohibit making a copy per se, does render any copy (recording) of the video signal relatively unviewable so that the viewer's enjoyment of the picture is severely reduced or none. Methods for reducing the effects and/or defeating copy protection are also known. The present method and apparatus reduce effects of added copy protection pulses by further adding other pulses that counteract the gain reduction caused by the copy protection pulses of the type known as automatic gain control (AGC) or pseudo-sync pulses.

Abstract: A watermarking scheme which allows the watermarked image to be authenticated by an authentication agent without revealing the human-readable content of the image. There is disclosed an approach which combines privacy control with watermarking and authentication mechanisms. The watermark can be made to be imperceptible to humans. Public key cryptography allows the authentication agent to authenticate without being able to watermark an image.