1. An imaging apparatus comprising: a light exposure condition determining unit that determines a plurality of exposure conditions based on a histogram of a luminance distribution of an imaging scene; an imaging unit that images, plural times, the imaging scene under the plurality of exposure conditions determined by the light exposure condition determining unit, and generates first and second raw image signals before synthesizing the first and second raw image signals; and an image synthesizing unit that synthesizes the first and second raw image signals using, as a boundary, a reference value contained in the first raw image signal to generate a synthesized image signal, wherein the light exposure condition determining unit determines at least one of the plurality of exposure conditions so that the reference value contained in the first raw image signal corresponds to a luminance value at a bottom of a ravine of the histogram of the luminance distribution of the imaging scene.