IMAGE FUSION AND SUBPIXEL PARAMETER-ESTIMATION FOR AUTOMATED OPTICAL INSPECTION OF ELECTRONIC COMPONENTS

We present a new approach to automated optical inspection (AOI) of cir cular features that combines image fusion with subpixel edge detection and parameter estimation. in our method, several digital images are t aken of each part as it moves past a camera, creating an image sequenc e. These images are fused to produce a high-resolution image of the fe atures to be inspected, Subpixel edge detection is performed on the hi gh-resolution image, producing a set of data points that is used for e llipse parameter estimation, The fitted ellipses are then back-project ed into 3-space in order to obtain the sizes of the circular features being inspected, assuming that the depth is known. The method is is ac curate, efficient, and easily implemented. We present experimental res ults for real intensity images of circular features of varying sizes, Our results demonstrate that our algorithm shows greatest improvement over traditional methods in cases where the feature size is small rela tive to the resolution of the imaging device.