| 摘要 |
<P>PROBLEM TO BE SOLVED: To prevent unauthorized copying by utilizing analog image signals by substantially degrading decoded signals in the second time and succeeding encoding and decoding operations. <P>SOLUTION: A reproducing machine 110 outputs an analog image signal Van1 accompanied by analog distortions (amplitude, phase). An encoding part 135 encodes a digital image signal Vdg1 obtained by performing A/D conversion for the image signal Van1. In the encoding of this case, degradation is increased when the image signal Van1 is accompanied by the analog distortions as mentioned above. For instance, block encoding using orthogonal transformation is performed. In the second and succeeding encoding and decoding operations, a block position is shifted from the block position in the first encoding and decoding due to the fluctuation of a sampling phase, and hence large degradation is generated by the encoding. By performing block formation accompanied by shuffling such that the correlation between pixel data at adjacent positions included in respective blocks becomes low, the degradation is further increased. <P>COPYRIGHT: (C)2005,JPO&NCIPI |
