METHOD AND APPARATUS FOR DETECTING DIGITAL WATERMARKING

摘要

A method and an apparatus for detecting digital watermarking are provided to accurately detect watermarking information weakened by an attack from high definition image signals without increasing an operation amount and the size of a circuit. An input image signal(10) having watermarking information inside is inputted to an image downscaler(11). The image downscaler scales down the input image signal. The scale-downed image signal is inputted to a watermarking information detector(12). The watermarking information detector detects the watermarking information from the scale-downed image signal. A specific frequency component extractor(21) extracts a signal of a specific frequency component. A phase controller(22) shifts a phase of the signal of the specific frequency component. A correlator(23) calculates a correlation value between the signal of the specific frequency component and the scale-downed image signal and inputs the calculated correlation value to a watermarking information estimator(24). The watermarking information estimator estimates watermarking information by searching a peak of the correlation value.