Fig. 1. Structural compositions of scratch defect detection system

Fig. 2. ROI images extracted under combination lighting mode. (a) Original image with low angle lighting; (b) original image with high angle lighting; (c) mask template; (d) ROI image

Fig. 3. Four kinds of morphological median filter kernels in different directions. (a) 0°; (b) 90°; (c) 45°; (d) 135°

Fig. 4. Background difference images for scratch extraction. (a) Background image by 13×13 median filter; (b) background image by morphological median filter; (c) background difference image by morphological median filter; (d) segmentation image of scratch binarization

Fig. 5. Schematic of scratch region growing

Fig. 6. Result of scratch region growing

Fig. 7. Flow chart of scratch detection based on weighted fusion of multi-features

Fig. 8. Scratch images extracted by different algorithms. (a) Gaussian filter; (b) median filter; (c) low-pass filter; (d) morphological median filter

Fig. 9. Scratch extraction error images obtained by different algorithms. (a) Gaussian filter; (b) median filter; (c) low-pass filter; (d) morphological median filter

Fig. 10. Experimental results of scratch detection