PURPOSE: To prevent the flicker of a screen generated by the brightness difference between adjacent picture elements at the time of converting the RGB signals outputted from a personal computer to NTSC signals and displaying these signals on a TV receiver.

CONSTITUTION: This circuit has an odd field memory 14 for storing the brightness values of the respective picture elements of odd fields, a brightness level deciding circuit 16 for odd fields for deciding whether the brightness values of the respective picture elements of the odd fields belong to the inside of white or black regions or not, a brightness level deciding circuit 22 for even fields for deciding whether the brightness values of the respective picture elements of the even fields belong to the inside of the white or black regions or not and a brightness conversion circuit 32 for making level conversion of the brightness values of the respective picture elements of the even fields in such a manner that the brightness differences between the picture elements of the adjacent odd fields are decreased and for outputting the level converted brightness values as the fresh brightness signals of the picture elements of the even fields.