| 摘要 |
PURPOSE:To obtain a compression ratio of about 2 times, by detecting a outline information, extracting only a picture element data in the outline, also deriving a difference between the picture element data and a reference data, and setting the bit length to half. CONSTITUTION:When a data of a difference is larger than a threshold level TH, a data of a data register 55 in this case is shifted to a data register 54, a data of this data register 54 is outputted as a reference data, and also a difference between said data and a data which is read out next and is stored in the data register 55 is outputted in the same way. Subsequently, when the data of a difference is stored in a data register 74 by which it has been read out, it is added to the reference data by an adder 76, bit restoration is executed,and this restored data is sent to a buffer RAM 83 of a position restoring part 8. A start position signal is compared with a value of a line address counter 81 and a row address counter 82 of the buffer RAM 83 by a comparator 84, and a data is generated from a space clear register 86. |
