1. A pixel interpolation circuit comprising: a correlation calculation unit which calculates correlation in a horizontal direction and correlation in a vertical direction with respect to a neighboring region around an interpolation target pixel having no G pixel, by using respective pixel values of R pixels, G pixels, and B pixels in the Bayer data: and a pixel value determination unit which determines pixel value of the G pixel to be interpolated for the interpolation target pixel, based upon pixel values of pixels adjacent to the interpolation target pixel along a direction exhibiting a stronger correlation between the correlations calculated by the correlation calculation unit, wherein the G pixel of the pixel value determined by the pixel value determination unit is interpolated for an image signal based upon the Bayer data.