According to one embodiment, a method can generate an interpolation image signal including the integer-pixel and interpolation pixel values, based on, if the interpolation pixel is not located at the integer-pixel position and in a row of an integer-pixel, and the interpolation pixel is located at a first pixel position displaced from the integer-pixel in horizontal and vertical directions by a half pixel, applying a first filter, and if the interpolation pixel is located at a second pixel position displaced from the integer-pixel in the directions by a quarter pixel, applying a second filter, and if the interpolation pixel is not located at the first and second pixel positions, applying the second and first filters.