| 摘要 |
PURPOSE:To easily detect defect of a closed loop image by dividing the closed loop image into lots of islands by means of sectorial areas having an equal apex angle whose apex is the center of the closed loop. CONSTITUTION:The method adopts a window that divides a closed loop image into k-sets of islands (k=360divided by (m+n)) by leaving an image included in sectorial areas having an equal apex angle of m deg. whose apex is the center of the closed loop and eliminating the image in the sectorial areas having an equal apex angle of n deg.. That is, the radial window in an area 24 has 72 window areas by selecting the apex angle (m) to be 3 deg. for an area 24a and the apex angle (n) to be 2 deg. for an rea 24b. The image in the area 24a is binarized by a prescribed threshold level but the image information of the area 24b is aborted. The area of each island is the same when no defect is in existence in the image by dividing radially the looped image, and then a difference from feret's diameters resulting from the position or the angle is reduced, and then whether or not a defect takes place in the image is easily discriminated based on the information of each island. |
