Device for optically scanning a record carrier

Linnartz, J.P.M.G.
Maes, M.J.J.J-B
Kalker, A.A.C.M.
Depovere, G.F.G.
Rongen, P.M.J.
Vriens, C.W.F.
van Dijk, M.E.

Publication date

July 2002

Language

English

Abstract

A watermark detector is disclosed to judge whether multimedia content can be copied or not. The watermark detector examines the multimedia content and outputs a signal indicating whether a watermark is present or not. A decision variable indicating to which extent the watermark is present is determined, for example, the amount of correlation between the input signal and a reference copy of the watermark to be detected. The watermark is detected if the decision variable exceeds a predetermined threshold (y2). The detector also generates a random output signal for a predetermined range of decision values between the threshold (y2) and a further threshold (y1)