| 摘要 |
PURPOSE:To improve the compression ratio even for originals having black colored grounds and half tone information, by converting plural bits as one unit, converting a unit in which black colored portions and white portions are mixed into an inherent code corresponding to the condition and converting the bit number until the next changing point into an MH code, for units whose whole area is black or white. CONSTITUTION:Bits are taken into a register 3 four bits by four bits, where the four bits are one unit. When a whole-white whole-black detecting circuit 5 judges an output from the register 3 as a unit in which black and white are mixed, a control circuit 8 reads out an inherent code corresponding to the output of the register 3 from an ROM6 and outputs the code through an inherent code processing circuit 7. In case where a unit is detected as a whole-white or whole-black by the detecting circuit 5, the control circuit 8 holds the reading out from a memory 1 and the operation of a run length counter 2, and stops the holding work when an output from a changing point detecting circuit 4 is obtd. At this time, the control circuit 8 reads out an MH code discrimination code addition corresponding to the run length number of the above mentioned counter 2 and outputs it through an MH code processing circuit 10. Then, the circuit 8 obtains the run length number until the next changing point from the memory 1 and outputs it after it is encoded into an MH code. |
