Patent ID: 7580155

Claim:
Apparatus comprising: a digital two-dimensional authentic image; an image processor; authentication message data representing an authentication message; a screen to be applied to at least a portion of the two-dimensional image, the screen applying two different halftoning operations including a first halftoning operation applying halftoning elements arranged in one way, and including a second halftoning operation applying halftoning elements in a second way, the first halftoning operation being applied in a limited area of the authentic image and in a form defined by the authentication message data, and the second halftoning operation being applied in an area surrounding the limited area; and a viewing key to render viewable the authentication message; wherein the halftoning elements of the first halftoning operation include parallel lines arranged at a first angle in relation to a horizontal line in the authentic image and wherein the halftoning elements of the second halftoning operation include parallel lines at a second angle in relation to the horizontal line, the second angle being different from the first angle.