Patent ID: 7409060

Claim:
A code stream producing apparatus comprising: at least one processor having a quantizer configured to quantize a frequency component obtained from a pixel value of an image through discrete wavelet transform to produce a set of quantized coefficients for each of a plurality of tiles of the image, a block processing unit configured to divide the set of quantized coefficients into a plurality of blocks, a hash conversion unit that carries out hash conversion for each of the blocks, based on the quantized coefficients of the block, to obtain an encoding hash value for each of the blocks, a bit plane defining unit configured to divide each of the blocks into a plurality of bit planes, a digital watermarking unit configured to adjust an ON/OFF state of significant bits such that the relation between information defined by N (N is an even number) significant bits Qnm(x, y) (x=0, 1, . . . , y=0, 1, . . . ) of the mth bit plane of the n th block and a natural number T satisfies either the ON state expressed by equation (1), or the OFF state expressed by equation (2), depending on whether the encoding hash value of the nth block is odd or even, in order to embed a digital watermark, and an encoding unit configured to encode the set of quantized coefficients containing the ON/OFF adjusted siguificant bits, wherein equation (1) is  ∑ k = 1 1 2 ⁢ N ⁢ ⁢ Qnm ⁡ ( ik , jk )  -  ∑ k = 1 2 ⁢ N + 1 N ⁢ ⁢ Qnm ⁡ ( ik , jk )  ≻ T , and wherein equation (2) is  ∑ k = 1 2 ⁢ N + 1 N ⁢ ⁢ Qnm ⁡ ( ik , jk )  -  ∑ k = 1 1 2 ⁢ N ⁢ ⁢ Qnm ⁡ ( ik , jk )  ≻ T .