The present invention relates to an interpolation method and a filtering method which utilize a correlation between pixel signals, and it is an object of the present invention to provide a sharp and high-quality image even if an error occurs in correlation degree judgment. To accomplish the above-mentioned object, an imaging device 10 is of a single-chip type, and includes a RGB Bayer pattern color filter 11, and an image is processed in a manner to be described below. Pixel signals outputted from the imaging device 10 are inputted through a signal processing part 20 to an image processing part 30. A correlation judgment part 31 judges a correlation between the pixel signals, and an interpolation processing part 32 performs a pixel interpolation process based on a correlation result. Thus, each pixel signal becomes a perfect signal having all R, G and B color components. Filter factors for a filter 34 are determined based on the correlation result, and a filtering process is performed on the pixel signals subjected to the pixel interpolation. The filter factors are determined so as to assist the pixel interpolation process best.