PURPOSE: To obtain a clear reduction picture.

CONSTITUTION: Respective signals converted into RGB signals by an RGB conversion circuit 15 are stored in corresponding memories 16, 17 and 18. When an address/operation control circuit 13 outputs a control signal to be reduced, respective operation circuits 19, 20 and 21 read data of one field from respective memories 16, 17 and 18 and execute a thinning processing for reducing the size of the picture to be displayed in 1/2. Then, respective operation circuits 19, 20 and 21 constitute a second field based on the remaining thinned signal. Thus, lacking field information at the time of compressing the first field is compensated at the time of constituting the second field.