초록 ▼

An identification code signal is hidden in a carrier signal (such as an electronic data signal or a physical medium) in a manner that permits the identification signal later to be discerned. The carrier signal can thereby be identified, or some machine responsive action can thereby be taken. The tec

An identification code signal is hidden in a carrier signal (such as an electronic data signal or a physical medium) in a manner that permits the identification signal later to be discerned. The carrier signal can thereby be identified, or some machine responsive action can thereby be taken. The technique can be applied in video imagery embodiments to control associated video equipment, e.g. to serve as a copy control signal.

대표청구항 ▼

1. A method of marking a security document to convey plural binary bits, thereby facilitating machine-recognition thereof, the security document having a visible image thereon, the method being characterized in that the marking is not apparent to human observers of the document, yet can be detected

1. A method of marking a security document to convey plural binary bits, thereby facilitating machine-recognition thereof, the security document having a visible image thereon, the method being characterized in that the marking is not apparent to human observers of the document, yet can be detected from image data generated by visible light scanning of said document.