Fig. 1. Reflections of zinc oxide nanoparticles

Fig. 2. Image acquisition system

Fig. 3. Generation process of random speckle projection group images

Fig. 4. The positional relationship between the projection light source and the workpiece

Fig. 5. Perspective distortion stereoscopic model

Fig. 6. Horizontal tilt projection distortion model

Fig. 7. The distortion relation between the generated projected image and the actual projected image in Y axis direction

Fig. 8. Distortion correction algorithm flow

Fig. 9. Intermediate process of trapezoidal distortion correction algorithm

Fig. 10. Isometric dot map projection correction

Fig. 11. The image acquisition experimental platform

Fig. 12. Random speckle projection group image fusion

Fig. 13. Workpiece samples images acquired in different light sources

Fig. 14. Detailed comparison of workpiece samples images acquired in different light sources

Fig. 15. Comparison of grayscale histogram

Fig. 16. Image contrast comparison in different light sources

Fig. 17. Comparison of character recognition detection results