1. An image processing apparatus comprising: a producing unit that produces a histogram based on values of pixels in an image; an analysis unit that performs a first correction process to a value of the histogram produced by the producing unit and analyzes a feature amount of the histogram after the first correction process is performed, using the value processed by the first correction process and a frequency corresponding to the value processed by the first correction process; and a calculation unit that calculates correction parameters used for a second correction process based on a result of the analysis by the analysis unit.