1. An image processing apparatus comprising: a calculating unit configured to calculate correlation values of captured images of a plurality of pairs of viewpoints, each pair being formed between respective viewpoints of a plurality of viewpoints using captured images of the respective viewpoints obtained by an imaging array including each viewpoint of the plurality of viewpoints; and a generating unit configured to generate a plurality of parallax images of different hierarchical levels of a reference viewpoint based on highest correlation disparity values among the plurality of pairs of viewpoints using the correlation values calculated by the calculating unit, the plurality of parallax images including a viewpoint parallax image formed with a disparity value of the reference viewpoint and an occlusion parallax image formed with a disparity value of an occlusion region, the reference viewpoint being one of the plurality of viewpoints viewing a region other than the occlusion region, wherein the calculating unit and the generating unit are each implemented via at least one processor.