| 摘要 |
PURPOSE:To correctly detect a central position of a hole part from an image of the hole part even when the hole part is such a special one that is colored and reflects light beams therein. CONSTITUTION:A light is cast from a light source to a work in a slantwise direction to a surface of the work, e.g. from diagonally below the surface to photograph a hole part of the work. Even when the hole part is special, a half of an image of the hole part at the same side as the light source corresponds in shape to the hole part. A plurality of points on the peripheral edge of the half image are picked up. A regression ellipse representing the image of the hole part is calculated on the basis of coordinates of a point in a predetermined annular area of the points at the peripheral edge. A central position of the hole part is obtained from coordinates of a center of the regression ellipse. |
