An image signal converting apparatus for converting a first image signal into a second image signal, where the first and second image signals include a plurality of pictures of different frames. A motion detector is operable to detect motion of the first image signal between a first frame and a second frame, and processing circuitry produces the second image signal based on an assumption of a pixel at a position corresponding to the detected motion. The apparatus may be employed to produce an output signal of either the same resolution as the first image signal with aliasing distortion reduced or eliminated, or with higher resolution in vertical and/or horizontal directions.