Imaging apparatus, vehicle system, and image-processing method for image magnification and expansion

A dynamic expansion operation of an index value image is performed by specifying an index value range before correction (Gmin to Gmax) for one index value image, calculating magnification K for which to be expanded to an ideal index value range (0 to 1023), and correcting an index value before correction G by the magnification K. An effective magnification Kthre to expand a maximum effective index value range (215 to 747) that can be taken by the index value before correction G calculated from transmittance of a filter to the ideal index value range (0 to 1023) is stored, and in a case where the calculated magnification K is smaller than the effective magnification Kthre, the expansion operation is performed by use of the effective magnification Kthre.