1. An image processing method comprising: adjusting a brightness of each of a first image and a second image based on a first exposure time when the first image is captured and a second exposure time when the second image is captured, respectively, the adjusted brightness of the first image corresponding to a brightness of the first image when the first image is captured over a unit exposure time, the adjusted brightness of the second image corresponding to a brightness of the second image when the second image is captured over the unit exposure time, the first and second images being generated by capturing a same object under different light conditions; estimating an intensity of light, reaching the object when the second image is captured, based on the adjusted brightness of each of the first and second images; separating the second image into two or more regions according to the estimated intensity of light; determining a target brightness that a final result image is to have; adjusting the brightness of the second image, by different amounts for each of the separated regions, based on the target brightness; and generating the final result image based on the adjusted brightness of the second image.