Adaptive Bilateral Filter for Sharpness Enhancement and Noise Removal

1. Adaptive Bilateral Filter for Sharpness Enhancement and Noise Removal Buyue Zhang, Jan P. Allebach, IEEE Trans. Image Process., vol. 17, NO. 5,MAY 2008 2009.11.09 王韋弘

2. Outline • Introduction • Bilateral Filter • Adaptive Bilateral Filter(ABF) • Role of in ξ the ABF • Role of in σr the ABF • Summary of the Rationale for the ABF • Results and Discussions

3. Introduction • Purpose： 1、edge-preserving 2、de-noising • Method：modifies the Bilateral Filter

4. Outline • Introduction • Bilateral Filter • Adaptive Bilateral Filter(ABF) • Role of in ξ the ABF • Role of in σr the ABF • Summary of the Rationale for the ABF • Results and Discussions

5. Bilateral Filter • shift-variant filtering： • ：restored image • ：degraded image ----response at [m,n] to an impuse at [k,l]

6. Bilateral Filter • σd , σr：the standard deviations of domain and range Gaussian filter

7. Blurred and noisy Bilateral Filter Bilateral filter σr=20, σd =2 Gaussian filter σd =2

8. Bilateral Filter

9. Bilateral Filter (a) the impulse response of the domain Gaussian filter (σ d= 2) (b)the impulse response of the range Gaussian filter at the edge pixel A (σ r= 2) (c) the impulse response of the bilateral filter at pixel A (d)the transfer function of (c) at pixel A

10. Bilateral Filter

11. Outline • Introduction • Bilateral Filter • Adaptive Bilateral Filter(ABF) • Role of in ξ the ABF • Role of in σr the ABF • Summary of the Rationale for the ABF • Results and Discussions

12. Adaptive Bilateral Filter(ABF) • Bilateral filter • ABF

13. Adaptive Bilateral Filter(ABF) • Some modifications： • an offset ξis introduced to the range filter • both ξ and σr are locally adaptive • σd=1 be fixed

14. Outline • Introduction • Bilateral Filter • Adaptive Bilateral Filter(ABF) • Role of in ξ the ABF • Role of in σr the ABF • Summary of the Rationale for the ABF • Results and Discussions

15. Adaptive Bilateral Filter(ABF) • A range filter shifted by the following choice forξ.

16. Adaptive Bilateral Filter(ABF) • 25X25 • σd=1 • σr=20

17. Adaptive Bilateral Filter(ABF)

18. Outline • Introduction • Bilateral Filter • Adaptive Bilateral Filter(ABF) • Role of in ξ the ABF • Role of in σr the ABF • Summary of the Rationale for the ABF • Results and Discussions

19. Adaptive Bilateral Filter(ABF) DF：σd=1 RF：σr=5 BF： σd=1 、σr=5 • DF：domain filter only • RF：range filter only • BF：bilateral filter

20. Adaptive Bilateral Filter(ABF) • DF：domain filter only • RF：range filter only • BF：bilateral filter DF：σd=1 RF：σr=50 BF： σd=1 、σr=50

21. Outline • Introduction • Bilateral Filter • Adaptive Bilateral Filter(ABF) • Role of in ξ the ABF • Role of in σr the ABF • Summary of the Rationale for the ABF • Results and Discussions

22. Adaptive Bilateral Filter(ABF)

23. Adaptive Bilateral Filter(ABF)

24. Adaptive Bilateral Filter(ABF)

25. Adaptive Bilateral Filter(ABF) • ξis the key to slope restoration. • The output is bounded between MIN(Ωm0,n0) and MAX(Ω m0,n0). • To smooth：shift RF towards MEAN (Ωm0,n0) use a large σr • To sharpen：shift RF away from the midpoint use a small σr

26. Outline • Introduction • Bilateral Filter • Adaptive Bilateral Filter(ABF) • Role of in ξ the ABF • Role of in σr the ABF • Summary of the Rationale for the ABF • Results and Discussions

27. Optimal unsharp mask

36. Results and Discussions ABF OUM