Method and apparatus for selectively transmitting information within a colour video signal

摘要

In a colour video transmission system, intelligible information, such as text, is transmitted on the blue colour component of the signal, and interference is transmitted on the red and green colour components. When the video display is viewed normally, the information cannot be discerned. If viewed through blue filter or blue spectacles, the green and red interference is rendered invisible and the information can now be seen. The interference may be random noise, but is preferably similar in type to the desired information, e.g. text. No modification is required to the receiver, and two viewers viewing the same display can decide independently whether to see the hidden information or not. <IMAGE>