Fig. 1. Schematic diagram of image-based angle displacement measurement system

Fig. 2. Schematic diagram of code disk and section

Fig. 3. Schematic diagram of different contamination conditions. (a) Rough code area; (b) precision code area

Fig. 4. Schematic diagram of decoding principle for rough code area. (a) Schematic diagram of code disk information; (b) pixel changes of baseline

Fig. 5. Flowchart for error code DCAF in rough code area

Fig. 6. Schematic diagram of precision code area. (a) Schematic diagram of precision code area information; (b) pixel changes in the scanning area

Fig. 7. Flowchart for error code correction in precision code area

Fig. 8. Real shot of error code detection and correction system

Fig. 9. Experiment of contaminations in rough code area. (a) Black contamination and (b) corresponding pixel change; (c) black scratches contamination and (d) corresponding pixel change

Fig. 10. Experiment of contaminations in precision code area. (a) Black cover contamination in blank space and (b) corresponding pixel change; (c) black cover contamination in precision code track and (d) corresponding pixel change; (e) black contamination and (f) corresponding pixel change; (g) black scratches contamination and (h) corresponding pixel change