PURPOSE: To execute a PinP display by constituting a reduced screen from still picture data encoded by a DCT.

CONSTITUTION: When a PinP flag is turned on, and DCT code still picture data stored in a buffer memory 12 is read out and decoded by an IDCT circuit 18, the IDCT circuit 18 decodes only low frequency blocks of 2×2 containing a DC component among 8×8 blocks by a switching signal from a control circuit 16. As a result, reduced screen image data which does not contain a high frequency component, that is, is equivalent to that which is processed by a low-pass filter is obtained. In such a way, the low-pass filter and a line memory, etc., become unnecessary, and the inexpensive circuit configuration is simplified.