PURPOSE: To obtain a highly accurate pattern just after a camera comes to a standstill state by detecting the presence of the motion of an image pickup camera so as to quantize the pattern while the camera is moving with rough accuracy.

CONSTITUTION: Sent picture data are divided by pattern division and an orthogonal transformation circuit 5 applies discrete cosine transformation (DCT) to difference data for each block. A quantization circuit 6 quantizes data from the orthogonal transformation circuit 5 in a step width represented by a quantization step width calculation circuit 10. A coding circuit 7 applies variable length coding to the quantized value and the motion vector and stores the result to a transmission buffer circuit 8. Picture data part when the camera is not moving are sent from the transmission buffer circuit 8 to a line with high accuracy, and picture data part when the camera is moving are sent with rough accuracy.