| 摘要 |
PURPOSE:To moderate constraint from an encoding method to a compression ratio, and to obtain a large compression ratio even in a variable density area by identifying the variable density area by every prescribed plural pieces of picture element pattern units, and making the plural pieces into a forecast encoding. CONSTITUTION:A counter 46 counts the number of variable patterns in consecutive picture element patterns, and a comparator 47 compares a counted result. An FF48 holds an identified result, and uses it in the selection of the encoding of the consecutive picture element patterns stored at shift registers 53-56. A ROM49 inputs a signal 43a from a line counter, and the contents of shift registers 42 and 53 to an address. The shift registers 42 and 53 become an encoding pattern and a reference pattern respectively, and the ROM49 outputs an appearance order when the encoding pattern is a gradation pattern, and when it is not the gradation pattern (non-gradation pattern), outputs a signal which represents the fact. Therefore, the content of a shift register 50 represents a forecasting result corresponding to the picture element patterns of the shift registers 53-56.
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