Fig. 1. Real star map

Fig. 2. Horizontal high frequency coefficient in third level after 2D wavelet transform to Fig. 1

Fig. 3. High frequency and low frequency coefficients after 2D wavelet transform to the experimental star map. (a) Horizontal high frequency coefficient; (b) vertical high frequency coefficient; (c) diagonal high frequency coefficient; (d) low frequency coefficient

Fig. 4. High frequency and low frequency coefficients obtained by fitting and subtracting. (a) Horizontal high frequency coefficient; (b) vertical high frequency coefficient; (c) diagonal high frequency coefficient; (d) low frequency coefficient

Fig. 5. Real local star map

Fig. 6. 3D energy of star map

Fig. 7. Star map processed by actual star sensor

Fig. 8. Denoised effect map after NL-means denoising

Fig. 9. Denoised effect map after WTD denoising

Fig. 10. Denoised effect map after LOF-WTD denoising

Fig. 11. 3D figure with NL-means

Fig. 12. 3D figure with WTD

Fig. 13. 3D figure with LOF-WTD