According to the present invention, it is possible to display an image signal with as a high picture quality as would have been obtained with a solid image pick-up device having color filters arrayed in a mosaic pattern. The image signal obtained from the solid image pick-up device with a Bayer array of the three primary colors of R, G, and B is separated by a color separation circuit 4 into R-color, G-color, and B-color signals. These color signals are attenuated by filters 6, 8, 10 respectively at half a horizontal sampling frequency in order to suppress the occurrence of moire noise. The G-color filter circuit 8 has a narrower attenuation band width than that of the R-color filter circuit 6 and the B-color filter circuit 10. These color signals thus filtered are adjusted in level at a white balance circuit 12 and then mixed by addition at a mixer 14, thus generating a luminance signal. By narrowing the attenuation band width of the G-color signal, the resolution can be kept high while suppressing the occurrence of moire noise.