WATERMARK DETECTION Russian patent published in 2009 - IPC G06T1/00 H04N7/08 G06K9/70 

FIELD: physics; measurements.

SUBSTANCE: present invention pertains to systems of marking images with a watermark, and particularly to detecting a watermark in an information signal. Proposed here is a detector (100) of presence of a watermark in an information signal. The information signal is correlated with the expected watermark (Wi) for each of set of relative positions of the information signal relative the watermark, so as to obtain a set of correlation results (64). A metric which, is a root-mean-square value, is calculated for the group of results (64). The metric is compared with a threshold value h, which indicates the group representing presence of a correlation peak. The metric can be calculated for groups, created in each position in the result buffer (64). Alternatively, the metric can be calculated only for the group, which is identified as the possible correlation peak.

EFFECT: increased efficiency of detecting a watermark in an information signal.

26 cl, 10 dwg