A new method is proposed to detect circular arcs. The detection of a circular arc includes the determination of its center, radius, length, and midpoint. The Hough transform is applied to detect circular arcs by using center and radius as parameters. A peak value in the parameter space of the Hough transform indicates the existence of a circular arc. The center and radius of the circular arc are given by the coordinates of the peak. The arc points are separated from the remaining edge points of the image. Then, the near-peak Hough transform data of the arc points is analyzed to determine the arc length and midpoint.