A method of measuring a modulation transfer function (MTF) includes detecting the center of a line spread function (LSF) image in order to calculate an MTF. For this purpose, an enlarged image of a portion of an image containing the LSF image is created, and binary-coded based on a threshold. A morphological operation is performed on the binary-coded image. Coordinates representing points that define the contour of the resultant image are sampled, and used to work out coordinates representing the center of a circle through Hough transform. The coordinates representing the center are transformed into coordinates representing a point in an original image.