A method for correcting an image includes: orthographically correcting an image; removing a curtain artifact by applying a first filter to the orthographically corrected image; correcting brightness of the image, from which the curtain artifact is removed, by applying a second filter to the image, from which the curtain artifact is removed. The first filter includes a first function and a second function for a first domain and a second domain, which are orthogonal to each other in a frequency region, and the first filter is differentiable and continuous in the first domain and the second domain.