抄録
This paper presents differential facing filter (DFF) in consideration of quantization for detecting foreign materials on an adhesive sheet. DFF is a binary filter for determining the target pixel is a foreign object or not. The determining method is based on gradient directions of two pixels. The two pixels consist of the target pixel and the facing pixel. Basically, if gradient directions of the two pixels are facing each other, DFF determines the two pixels are a foreign object. Otherwise, DFF determines the two pixels are other. However, DFF without consideration of quantization has a spatial quantization problem to select the facing pixel. Therefore, DFF in consideration of quantization select the facing pixels in horizontal direction and vertical direction. In experiments, we demonstrate that this method is capable of discriminating between foreign materials and others. We test our method on several data sets made by ourselves. The results show that our method achieves better performance compared to adaptive thresholding.
