Patent ID: 6505223
Filing Date: 2003-01-07
Classification: G06T,H04H,H04N

Abstract:
A method of detecting a watermark in an information signal, comprising the steps of:computing a value indicative of the correlation of said information signal and said watermark; and detecting whether said correlation value is larger than a predetermined threshold; wherein said computing comprises the steps of Fourier transforming the information signal and the watermark into respective Fourier coefficients, multiplying corresponding coefficients to obtain Fourier coefficients representing correlation values each corresponding with one of a plurality of positions of the watermark with respect to the information signal, and inverse transforming the Fourier coefficients representing the correlation values; said step of detecting comprises detecting whether at least one of said correlation values is larger than the predetermined threshold; the method further including the step of normalizing the Fourier coefficients representing the correlation values to substantially the same magnitudes.