| 摘要 |
An encoder, which comprises a means (40) for embedding a specific electronic mark data in a characteristic part of an image converted to a spatial frequency area, a quantizing means (50) for quantizing the spatial frequency area data in which the electronic mark data is embedded and a variable length encoder (60) for variable length coding the quantizer output, outputs compression coded digital image data. A decoder comprises a variable length decoder (80) and reverse quantizer (90) for restoring compression encoded digital image data to spatial frequency area data, means (120) for detecting the electronic mark data from the restored data, and detection display means (130) for displaying the detection result. <IMAGE> |
