Nec Corporation

Fumihiro Okazaki

Hirotaka Nakano

Shiro Fujihara

Yasuhiko Okuhara

An encoder, which comprises a means,for embedding a specific electronic mark data in a characteristic part of an image converted to a spatial frequency area, a quantizing means,for quantizing the spatial frequency area data in which the electronic mark data is embedded and a variable length encoder,for variable length coding the quantizer output, outputs compression coded digital image data. A decoder comprises a variable length decoder,and reverse quantizer,for restoring compression encoded digital image data to spatial frequency area data, means,for detecting the electronic mark data from the restored data, and detection display means,for displaying the detection result.

Image data processor

Information generated by a terminal is delivered to an ATM transmission circuit, which assembles a cell from the information and inserts the cell into a transmission cell stream. An unassigned cell and an idle cell that do not contain information to be actually transmitted are removed from the transmission cell stream by an ineffective cell removing circuit. Only a cell which contains information to be actually transmitted is held by a FIFO memory until a transmission time. The reception by an ATM reception circuit of a cell representing a reference time is detected by a received VPI/VCI detecting circuit. The time at which to output the transmission cell from the FIFO memory to a circuit line is determined by a timer with respect to the reference time. In response to the determined time, a transmission control circuit reads the transmission cell from the FIFO memory, and delivers the transmission cell to the circuit line.

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Tokyo, Japan

Fumihiro Okazaki