Fig. 1. HSI color model. (a) Double cone model; (b) hue distribution

Fig. 2. RGB plane with I=0.5

Fig. 3. Measurement hardware system

Fig. 4. Comparison of projected images before and after color correction. (a) Before color correction; (b) after color correction

Fig. 5. Hue correction contrast. (a) Hue and ideal hue after correction; (b) error distribution of hue after correction

Fig. 6. System structure diagram

Fig. 7. Calibration of measurement system. (a) Calibration method of mapping relationship between h and ΔH; (b) height error

Fig. 8. Repeated measurement results of standard gauge block grinding surface. (a) Height contour; (b) measurement error

Fig. 9. Corresponding color of hue values in range of 0°-360°

Fig. 10. Process of calculating hue components of color projection pattern. (a) Grayscale transformation relationship corresponding to 0°-360°; (b) color projection pattern; (c) normalized conversion to hue gamut; (d) hue distribution at mark line

Fig. 11. Schematic of wrapped hue and color bar coding cut line

Fig. 12. Dividing process of fringe boundary on discontinuous surface. (a) Wrapped hue; (b) color bar coding; (c) fringe boundary division; (d) boundary division section line

Fig. 13. Hue unwrapping results. (a) Three-dimensional result; (b) section of hue unwrapped at marking line

Fig. 14. Measurement results of aero-engine compressor blades. (a) Captured image of blade; (b) color pattern; (c) wrapped hue value; (d) color bar code; (e) three-dimensional shape of compressor blade

Fig. 15. Error distribution of proposed method

Fig. 16. Compressor blade profile parameters