PURPOSE: To compress the number of scanning lines by preventing the generation of luminance difference between mutual scanning lines at the time of converting a signal from a computer system into a signal to be displayed on a TV receiver.

CONSTITUTION: The video signal from a video signal input section 1 is applied to digital conversion by an A/D conversion section 2 and recorded on a line memory 3. Based on the horizontal synchronizing signal from a synchronizing signal input section 4, a clock signal generation section 5 generates into the required clock signal. With the signal as a reference, an interpolation coefficient arithmetic section 6 calculates the interpolation coefficient at separate number of scanning lines of the video signal. A multiplier 7 multiplies the scanning line data read out from the above mentioned line memory by the interpolation coefficient of the pertinent next number from the interpolation coefficient arithmetic section. A multiplier 8 multiplies the next scanning line data of the above mentioned scanning line by the pertinent next number's interpolation coefficient. An adder 9 adds the data from the multipliers 7 and 8. A multiplier 10 multiplies the required coefficient. A scanning conversion section 11 converts it into a interlaced scanning signal. A D/A conversion section 12 converts it into an analog signal and output the result.