1. A method of segmenting a motion area from a current image, the method comprising: obtaining a background image of the current image by using a previous image of the current image; obtaining a difference image between the current image and the background image; obtaining a level set function of the current image to minimize an energy function of the current image comprising a regularized energy of the motion area of the difference image and a regularized energy of a non-motion area of the difference image; and segmenting the motion area from the current image based on the level set function, wherein the regularized energy of the motion area is obtained by using a difference between a first standard value generated by using the difference image, corresponding to an average pixel value of the motion area, and the difference image, and the regularized energy of the non-motion area is obtained by using a difference between a second standard value generated by using the difference image, corresponding to an average pixel value of the non-motion area, and the difference image, and wherein the obtaining the level set function comprises iteratively calculating the level set function n+1 times, where n is an integer equal to or greater than 1, and the level set function obtained at a k-th calculation is calculated based on a level set function obtained at a (k−1)-th calculation, the difference image, the first and second standard values used to obtain the level set function obtained at the (k−1)-th calculation, where k is an integer equal to or greater than 2 and equal to or less than n+1, and wherein, by the iteratively calculating, the level set function of the current image and the first and second standard values of the current image change at each time of the iterative calculating.