judgment of the step s 26 in the case when the processing corresponding to one frame has ended the picture data transfer processing element 22 moves the pointer b of the frame data buffer 3 to the head of the line step s 27 at the step s 28 the lower black frame data transfer processing element 23 transfers the black data to the picture element of the frame data buffer 3 shown by the pointer b the lower black frame data transfer processing element 23 moves the pointer b to the picture element adjacent to the present picture element step s 29 at the step s 30 the lower black frame data transfer processing element 23 judges whether the processing transfer of the black data corresponding to one line has ended or not in the case when the processing corresponding to one line has not ended the lower black frame data transfer processing element 23 moves to the processing of the step s 28 as a result of the judgment of the step s 30 in the case when the processing transfer of the black data corresponding to one line has ended the lower black frame data transfer processing element 23 moves the pointer b to the head of the next line step s 31 at the step s 32 the lower black frame data transfer processing element 23 judges whether the transfer of the black data corresponding to 1 12 u00d7 h lines has ended.