Electronic spacing pad manner, the electronic spacing pad program, the electronic spacing pad device, image coded manner, the image

摘要

PPROBLEM TO BE SOLVED: To surely leave watermark data even in the case of decoding an encoded image inserted with the watermark data. PSOLUTION: Run length structures obtained after quantizing DCT coefficients of blocks are arranged as many as the number of the blocks for grouping are converted into an N-bit hash value with a hash function. However, one dummy run is attached to the last of the run length of each block. Next, watermark data are embedded by taking an exclusive OR of the N-bit hash value and the watermark data, and the watermark is encrypted with a private key to obtain N-bit signature data. The N-bit signature data embedded with the watermark data in this way is obtained by one bit for each block, wherein a value behind a dummy run of the block is defined as -1 when the bit is 0, and a value behind the dummy run of the block is defined as +1 when the bit is 1. PCOPYRIGHT: (C)2004,JPO&NCIPI