Digital watermark-embedding and detecting

摘要

A dividing unit (102) divides digital image signal into blocks that are formed by several pixels. The divided blocks are transformed into several frequency components. The values of the frequency components are operated under predetermined rule in accordance with an embedment signal which is a digital watermark, such that the variation amount in image within the blocks follow a specific pattern. Independent claims are also included for the following: (1) digital watermark detector; (2) digital watermark embedding method; (3) digital watermark detecting method; (4) recorded medium storing digital watermark embedding program; and (5) recording medium storing digital watermark detecting program.