PURPOSE: To reduce the cost by processing a time base IIR filter in the 2-screen transmission system with one filter circuit so as to reduce the circuit scale.

CONSTITUTION: A multiplexer circuit 1 multiplexes image data a, b alternately for each image frame to obtain multiplexed data (c). A subtracter circuit 2 obtains a difference between the multiplexed data (c) and delay data (e) to obtain a difference (d). A coefficient arithmetic circuit 3 multiplies a circuit selected by a coefficient selection signal (f) with the difference data (d) to be received and gives the result to an adder circuit 4. The adder circuit 4 adds the delay data (e) to output data from the coefficient arithmetic circuit 3 to obtain local decoding data (g). The obtained local decoding data (g) are fed to a 2-frame delay circuit 5 and fed to an output terminal 8.