Fig. 1. Principle of detecting the signal catastrophe-points with wavelet transform

Fig. 2. Defect images of solar cells. (a) Scratch; (b) scratch and spot; (c) abrasion

Fig. 3. Flow chart of algorithm

Fig. 4. Capture of the signal catastrophe-points

Fig. 5. Correction of the signal catastrophe-points

Fig. 6. Calibration process of column signal from defect images. (a) Scratch in the 200th column; (b) scratch and spot in the 222nd column;(c) abrasion in the 80th column

Fig. 7. Background corresponding to the defect images. (a) Scratch; (b) scratch and spot; (c) abrasion

Fig. 8. Defect images and processing results. (a) Scratch; (b) scratch and spot; (c) abrasion