1. An image capturing apparatus comprising: an optical system that provides an aberration to incident light; an image capturing unit that transforms the light passing through the optical system into pixels to capture an image; and an inverse transform unit that performs inverse transform processing on the image captured by the image capturing unit in a predetermined range on an optical axis of the optical system using an inverse transform filter that causes frequency characteristics of pixels in an output image in two or more of defocus positions within the predetermined range to include at least one frequency characteristic with a larger value and at least one frequency characteristic with a smaller value with respect to frequency characteristic of pixels in an ideal image of a subject.