Patent ID: 7672474

Claim:
A digital watermark detection apparatus for detecting digital watermark information from an image on which a two dimensional waveform pattern is superimposed on each pixel block, the digital watermark detection apparatus comprising: a block dividing unit configured to divide an input image into plural pixel blocks; a block-by-block detection unit configured to, for a pixel block on which the two dimensional waveform pattern is superimposed, determine a frequency, of the two dimensional waveform pattern, having a larger energy from two kinds of frequencies associated with a sign + and a sign −, to obtain a sign corresponding to the determined frequency, and to obtain a value according to the sign as a detection value corresponding to the pixel block; and a watermark information despreading unit configured to despread a series of detection values corresponding to the plural pixel blocks obtained by the block-by-block detection unit so as to detect the digital watermark information embedded in the image.