Patent ID: 7231062

Claim:
An image processing apparatus for detectably embedding prescribed watermark information in original image information, comprising: an original image information dividing section for dividing the original image information into n×n blocks (n is a natural number); a discrete cosine transform section for performing discrete cosine transforms of the image information on a block-by-block basis; a quantization section for quantizing discrete cosine coefficients produced by the discrete cosine transform; and a watermark information embedding section for dividing the quantized discrete cosine coefficients into at least two data streams, and setting the value of an AC component of each of the data streams such that the value of the least significant bit of the sum of a plurality of data of each of the data streams, or the value of the least significant bit of the sum of a plurality of data of a prescribed portion of each of the data streams, is in a prescribed relationship with the value of the watermark information, so as to embed the watermark information in the original image information.