| 摘要 |
The disclosure describes a polar transformed image to unwrap and flatten a region of interest of a plurality of similar objects under inspection. Gray scale values of the flattened images are analyzed and plotted on a curve in the direction of polar rotation, and smoothing may be applied. The first derivative of the gray scale value curve is plotted as a first derivative curve, that is, the slope of the tangent line along the curve of gray scale values. The slope of the tangent line represents a change in the appearance of the flattened image. A plurality of such curves for non-defective objects provides a range of expected values along the curves. |
