In order to effectively and efficiently perform noise reduction by smoothing, an image processing apparatus of the present invention includes an image inputting part inputting an image in which a first pixels and a second pixels indicating mutually different color components are included and at least the second pixels are arranged at discrete positions, a color estimating part estimating first color component data at the second pixels based on first color component data of the first pixels, a calculating part calculating color-difference data at the second pixels based on the first color component data at the second pixels and second color component data of the second pixels, a smoothing part performing smoothing processing on a discrete color-difference image formed of the color-difference data being calculated at the second pixels, and a color-difference estimating part estimating color-difference data at pixels other than the second pixels on the input image.