Fig. 1. Experimental platform of sorting metal fragments

Fig. 2. Flow chart of extracting contour of metal fragments^[13]

Fig. 3. Extracting contours of metal fragments. (a) Without information filtering; (b) with information filtering

Fig. 4. Extracting window pictures of metal fragments

Fig. 5. Scatterplot of metal fragment texture feature data

Fig. 6. Histograms of metal fragment color feature. (a) Aluminum; (b) copper; (c) steel

Fig. 7. Curve of cumulative explained variance contribution rate

Fig. 8. Classification results of cross-validation