Fig. 1. Flow chart of pineapple thorn detection

Fig. 2. Image with background removed

Fig. 3. Image filtering

Fig. 4. Removing image shadows

Fig. 5. Global thresholds

Fig. 6. Adaptive thresholds

Fig. 7. Morphological processing results. (a) Binary graph; (b) corrosion; (c) expansion; (d) closed operation

Fig. 8. Result of division of connected area

Fig. 9. Connected domain contour

Fig. 10. Processing results

Fig. 11. Detection results

Fig. 12. Coordinate system

Fig. 13. Schematic diagram of geometric relations

Fig. 14. Projection relation

Fig. 15. Sectional data

Fig. 16. Schematic diagram of constant length arc projection

Fig. 17. Original image

Fig. 18. Detection results of simple speckle detection algorithm

Fig. 19. Detection results of the proposed method

Fig. 20. Experimental platform

Fig. 21. Pineapple image