To enhance the resolution of a color difference signal even of a natural image without compromising the quality, when restoring to a digital video signal having a color difference signal of a predetermined format different from a format at the input time.

Vertical interpolation units 11, 12 perform vertical interpolation of the color difference signals Pb, Pr in a 4:2:0 signal, corresponding to the luminance signal Y in the 4:2:0 signal. Vertical enhancement units 13, 14 perform vertical emphasis processing of the color difference signals Pb, Pr after vertical interpolation, and output a color difference signal Pb converted to a 4:2:2 format. Horizontal interpolation units 15, 16 perform horizontal interpolation of the color difference signals Pb, Pr in a 4:2:2 format, after vertical interpolation and vertical emphasis processing, corresponding to the luminance signal Y in the 4:2:0 signal. Horizontal enhancement units 17, 18 perform horizontal emphasis processing of the color difference signals Pb, Pr after horizontal interpolation, and output color difference signals Pb, Pr converted to a 4:4:4 format.