1. A method for detecting an ellipsoid using a computer, the method comprising: extracting an ellipsoid candidate; extracting an ellipsoid contour; calculating an ellipsoid parameter; calculating an adaptability ratio; and eliminating the ellipsoid candidate, wherein the step of extracting the ellipsoid candidate includes steps of: inputting an image having various figures; selecting the ellipsoid candidate from the various figures in such a manner that the ellipsoid candidate satisfies a predetermined condition; and extracting a contour candidate point and a center point of the ellipsoid candidate, the step of extracting the ellipsoid contour includes steps of: drawing a plurality of straight lines passing through the center point of the ellipsoid candidate; determining a pair of contour candidate points, which is a pair of cross points between each straight line and a contour of the ellipsoid candidate; calculating a first distance between one of a pair of contour candidate points and the center point; calculating a second distance between the other one of a pair of contour candidate points and the center point; and defining a pair of the contour candidate points as a pair of ellipsoid contour points when a difference between the first and second distances is disposed in a predetermined range, the step of calculating the ellipsoid parameter is performed based on a pair of ellipsoid contour points and the center point, the step of calculating the adaptability ratio includes steps of: drawing a complete ellipsoid based on the ellipsoid parameter; and calculating the adaptability ratio between a contour of the complete ellipsoid and the contour of the ellipsoid candidate, and the step of eliminating the ellipsoid candidate is performed when the adaptability ratio is equal to or smaller than a predetermined threshold.