1. An image capturing apparatus comprising: an imager includes an image sensor in which reference band pixels, first additional band pixels, and second additional band pixels are arranged, wherein the imager is configured to capture an object image by the image sensor receiving incident light from an object, wherein the reference band pixels include R band pixels, G band pixels, and B band pixels that have spectral sensitivity peak wavelengths in a R band, a G band, and a B band, respectively, wherein the first additional band pixels each have a spectral sensitivity peak wavelength between the spectral sensitivity peak wavelengths of the R band and the G band, wherein the second additional band pixels each have a spectral sensitivity peak wavelength between the spectral sensitivity peak wavelength of the G band and the B band, and wherein, in the image sensor, a number of the first additional band pixels and the second additional band pixels is smaller than any of: a number of the R band pixels, a number of the G band pixels, and a number of the B band pixels; an obtaining unit configured to obtain reference band pixel values detected by the reference band pixels of the image sensor and additional band pixel values detected by the first additional band pixels and the second additional band pixels in the object image captured by the imaging unit; a spectral analyzer configured to obtain a feature quantity in spectral characteristics of the incident light by comparing an additional band pixel value with a threshold value set according to the reference band pixel values; and an image processor configured to perform a chromatic aberration correction process on the object image based on the feature quantity.