1. An image processing apparatus comprising: an image dividing unit which receives a three-dimensional (3D) image and divides the 3D image into a left-eye image and a right-eye image; a histogram generation unit which estimates disparities between the left-eye image and the right-eye image, measures a frequency with which the estimated disparities occur, and generates a histogram of the disparities and the frequency; a horizontal movement value determination unit which determines a horizontal movement value for the left-eye image and the right-eye image using the generated histogram; and a horizontal movement unit horizontally which moves at least one of the left-eye image and the right-eye image based on the determined horizontal movement value.