1. An image processing apparatus for processing an object scene image outputted from an imager for capturing the object scene through a focus lens and an aperture mechanism, comprising: a focus adjuster for adjusting a focus in such a manner as to fit a specific object within the object scene; an aperture amount setter for setting a plurality of aperture amounts different to one another to said aperture mechanism in association with an adjusting process of said focus adjuster; a detector for detecting a magnitude of a difference in sharpness between a plurality of object scene images outputted from said imager corresponding to the plurality of aperture amounts set by said aperture amount setter; and an image quality adjuster for performing an image-quality adjusting process that refers to a detection result of said detector on the object scene image outputted from said imager corresponding to the focus adjusted by said focus adjuster.