Fig. 1. System of multi-spectral data acquisition

Fig. 2. Multi-spectral image of coal and coal gangue

Fig. 3. Structures of YOLO and YOLO v3 models

Fig. 4. Schematic diagram of YOLO v4.1

Fig. 5. Average recognition accuracy in different bands. (a) Two classes of coal and coal gangue; (b) three classes of coal, coal gangue, and mix

Fig. 6. Confusion matrix of correlation coefficients

Fig. 7. Test results. (a) Coal416; (b) coal512; (c) coal608; (d) coal408; (e) coal gangue416; (f) coal gangue512; (g) coal gangue608; (h) coal gangue408

Fig. 8. Detection result of YOLO v4.1