At least one image processing apparatus is provided which allows performing a demosaicing process on a polychrome image signal with high accuracy. The at least one image processing apparatus performs an interpolation process in each of a plurality of defined directions on a mosaic image signal and acquires an evaluation value representing a correlation in each of a horizontal direction and a vertical direction for each of a plurality of pixels of the image signal having undergone the interpolation process. The evaluation values for at least one pixel of interest are corrected based on the evaluation values for peripheral pixels if a predetermined condition including a condition that it is determined that the at least one pixel of interest is an isolated point is satisfied. Then, the image signal after the at least one pixel of interest is interpolated based on the corrected evaluation values.