| 摘要 |
<p>PROBLEM TO BE SOLVED: To decrease block distortion and to prevent number of imbed available bits and number of blocks from being reduced with respect to an electronic watermark imbedding device and method that imbeds copyright information of images or the like as an electronic watermark. SOLUTION: A block coding section 10 converts e.g. 2-bit in an input bit string 5 into an m×n block code. A block pixel value conversion section 20 quantizes a difference between a reference value Sb of an ms×ns block and a pixel value Xi, j from a block division section 14 which a larger step Qb than an imbed strength kb before imbedding an electronic watermark and coverts the value Xi, j into a pixel value Xi, j, according to the quantized value and the reference value Sb, A block code imbedding section 24 uses the value Xi, j, and the quantization step Qb to imbed block codes BCi, j from the block coding section 10 according to formula 1.</p> |
