1. A method of converting an image rate by using image scaling, the method being implemented by a processor and comprising: changing a resolution of an input original image sequence and generating a changed resolution image sequence; determining a first motion vector by estimating motion of a first image by using a plurality of images from the changed resolution image sequence; determining a second motion vector by modifying the first motion vector of the first image to correspond to a resolution of an original image of the original image sequence, wherein the original image corresponds to the first image; detecting characteristic information of the original image; determining a third motion vector corresponding to the resolution of the original image by compensating the second motion vector based on the detected characteristic information; and converting an image rate of the input original image sequence based on the detected characteristic information of the original image and the third motion vector.