Patent ID: 7894628

Claim:
A digital watermark detection apparatus to detect the watermark information from an input image signal, comprising: a scaling unit configured to generate a scaled image signal by scaling one of an input image signal embedded with watermark information and a first accumulated signal obtained by accumulating the input image signal over a certain period of time; a first transformation unit configured to obtain a first orthogonal transformation image signal and a second orthogonal transformation image signal by subjecting one of the input image signal, the first accumulated signal and the scaled image signal to orthogonal transformation; a complex addition unit configured to obtain a complex addition signal by subjecting the first orthogonal transformation image signal and second orthogonal transformation image signal to complex addition; a second transformation unit configured to obtain a transformation complex addition signal by subjecting the complex addition signal to orthogonal transformation or inverse orthogonal transformation; and an estimation unit configured to estimate the watermark information based on a peak which appears at one of the transformation complex addition signal and a second accumulated signal obtained by accumulating the transformation complex addition signal over a period of time.