A luminance signal in which the occurrence of spatial aliasing in a diagonal direction component has been suppressed for a red or blue imaging subject is generated from an image signal read from an image sensor. A V-LPF and a H-LPF generate a first luminance signal in which the spatial frequency bandwidth has been limited. Also, a V-LPF and a H-LPF, which limit the spatial frequency bandwidth so as to be even lower than the V-LPF and the H-LPF, generate a second luminance signal in which the bandwidth has been limited. A first GR weighted-addition circuit generates a final luminance signal for a pixel of interest by performing weighted-addition on the first luminance signal and the second luminance signal such that the ratio of the second luminance signal increases as the intensity of the redness or blueness of the pixel of interest increases.