Image capturing apparatus and image processing apparatus

An image processing apparatus comprising:

• an image acquirer configured to acquire an input image produced by using an output from an image sensor configured to capture an optical image formed by light entering an imaging optical system from an object space,
• the image sensor including (a) multiple pixels each including at least one photoelectric convertor and (b) a transmittance distribution provider configured to provide, to at least part of the multiple pixels, a transmittance distribution depending on an incident angle of the light,
• the multiple pixels including an adjacent pixel group that includes a first pixel and second pixels adjacent to the first pixel, the adjacent pixel group including pixels to which mutually different four or more kinds of the transmittance distributions are provided;
• and
• a producer configured to:
• acquire information on the transmittance distributions of the multiple pixels, and
• produce, by using (a) an input image produced from an output of the image sensor and (b) information on the transmittance distributions, an output image corresponding to an optical observation image observable when the object space is observed from a partial area of a pupil of the imaging optical system.