JPH0115187B

PURPOSE:To keep an input speed constant and to attain high speed data compression, by providing a buffer for 2 scanning line's share and an overrun detection logic and eliminating a bit series for one scanning's share at the generation of overrun. CONSTITUTION:Buffers 1 and 2 for each one scanning line's share are provided for a quantized bit series input 8. A data compression logic 3 compresses data for one scanning's share from the buffers 1 and 2 and writes the data to a memory 4. If the logic 3 can not compress the data for one scanning's share within an input time of quantized bit for one scanning's share, an overrun detection logic 6 detects it and stops the changeover between the buffers 1 and 2 so that the bit series for one scanning's share can be eliminated. A data recovery logic 7 expands this compressed data for the missing data bit series after the end of completion. Thus, the input speed of the quantized bit series can be kept constant and the speed-up of the system can be made.