METHOD AND APPARATUS FOR DETERMINING AN OPTIMUM FREQUENCY RANGE WITHIN A FULL FREQUENCY RANGE OF A WATERMARKED INPUT SIGNAL

摘要

Many watermarking detection algorithms are correlation based, whereby an input signal is correlated with reference signals. The correlation with the best match determines the bit value of the watermark information. Usually a watermarked signal undergoes distortion before being fed to a watermark detector. However, the modification is stronger in some frequency ranges than in others. According to the invention, the correlation result for a current input signal section is in addition used for estimating the optimal frequency range or ranges for the following section's correlation, using a cumulative correlation value curve.