Abstract: A horizontal filter used for converting a Moving Picture Experts Group (MPEG) source input format (SIF) picture to a CCIR 601 picture during decoding includes operating means for obtaining products by effectively multiplying an input picture signal with the coefficients 140 and -12, first selecting means for selectively outputting the values effectively multiplied by 140 and -12 obtained from the operating means in a sequence of the input picture signal, an accumulator for accumulating the signals output from the first selecting means, second selecting means for selectively outputting the input picture signal and signals output from the accumulator, and a controller for controlling the selection operation of the first and second selection means and the accumulation by the accumulator.