Fig. 1. Schematic diagram of camera calibration

Fig. 2. Experimental samples of duck eggs

Fig. 3. Images of duck eggs with different definitions

Fig. 4. Sharpness changes based on (a) the Laplacian operator and (b) spectrum

Fig. 5. (a) and (e) are egg images, (b) and (f) are original spectral images, (c) and (g) are frequency-intercepted spectral images, (d) and (h) are time-domain images corresponding to the spectral images after frequency interception

Fig. 6. (a) The definition change curve after the frequency interception; (b) the change of original definition

Fig. 7. The flow chart of ranging algorithm based on edge retaining defocus image

Fig. 8. The correlations between observed distance and calculated distance

Fig. 9. The process of image rotation. (a) Original image; (b) rotated image

Fig. 10. The correlation between observed distance and calculated distance for oblique duck eggs after rotation treatment

Fig. 11. Clarity change of group 10 of egg No. 4

Fig. 12. Relationship between natural logarithmic clarity and object distance of egg No. 4

Fig. 13. The relative error of the object distance from fitting model