Patent ID: 7356700

Claim:
A digital watermark-embedding apparatus comprising: an embedment signal-generating unit operable to generate an embedment signal in accordance with embedment information, the embedment signal being embedded as a digital watermark; a block-dividing unit operable to divide a digital image signal into blocks that are formed by several pixels; an orthogonal transform unit operable to practice orthogonal transformation of each of the blocks, thereby transforming the blocks into several frequency components; a digital watermark-embedding unit operable to operate, under a predetermined rule, a value of at least one of the several frequency components in accordance with the embedment signal generated by said embedment signal-generating unit, in which the value is operated in such a manner that amounts of variations in image within the blocks follow a predetermined specific pattern in consideration of detection; a first characteristic amount-extracting unit operable to extract a first characteristic amount in accordance with the several frequency components; and a selecting unit operable to select a value of at least one of the several frequency components in accordance with the extracted first characteristic amount; wherein the specific pattern has two different regions arranged in alternating sequence, one of the two different regions being where the amounts of variations in image serve as positive, and the other region being where the amounts of variations in image serve as negative; and wherein the first characteristic amount is a combination of one or more frequency components selected from a total of specific frequency components corresponding to vertical edges in an image within the blocks, a total of specific frequency components corresponding to horizontal edges therein, and a total of specific frequency components corresponding to slanted edges therein.