1. An image processing apparatus comprising: an image input unit configured to receive a long exposure image and a short exposure image that have different exposure times; a motion artifact area detecting unit configured to detect a motion artifact area resulting from a fusion of the long exposure image and the short exposure image; a non-linear gain adjusting unit configured to generate a non-linear gain control short exposure image by non-linearly adjusting a gain of the received short exposure image, wherein the adjusting adjusts a luminance component of the short exposure image to correspond to a luminance component of the long exposure image, and the non-linear gain adjusting unit is further configured to compensate for motion in the generated non-linear gain control short exposure image based on the detected motion artifact area; and a fusing unit configured to fuse the non-linear gain control short exposure image and the long exposure image to output an image to which a wide dynamic range (WDR) process is performed.