Name
Title | ||
|---|---|---|
Polyharmonic smoothing splines and the multidimensional Wiener filtering of fractal-like signals. |
Abstract | ||
|---|---|---|
Motivated by the fractal-like behavior of natural images, we develop a smoothing technique that uses a regularization functional which is a fractional iterate of the Laplacian. This type of functional was initially introduced by Duchon for the approximation of nonuniformily sampled, multidimensional data. He proved that the general solution is a smoothing spline that is represented by a linear combination of radial basis functions (RBFs). Unfortunately, this is tedious to implement for images because of the poor conditioning of RBFs and their lack of decay. Here, we present a much more efficient method for the special case of a uniform grid. The key idea is to express Duchon's solution in a fractional polyharmonic B-spline basis that spans the same space as the RBFs. This allows us to derive an algorithm where the smoothing is performed by filtering in the Fourier domain. Next, we prove that the above smoothing spline can be optimally tuned to provide the MMSE estimation of a fractional Brownian field corrupted by white noise. This is a strong result that not only yields the best linear filter (Wiener solution), but also the optimal interpolation space, which is not bandlimited. It also suggests a way of using the noisy data to identify the optimal parameters (order of the spline and smoothing strength), which yields a fully automatic smoothing procedure. We evaluate the performance of our algorithm by comparing it against an oracle Wiener filter, which requires the knowledge of the true noiseless power spectrum of the signal. We find that our approach performs almost as well as the oracle solution over a wide range of conditions. |
Year | DOI | Venue |
|---|---|---|
2006 | 10.1109/TIP.2006.877390 | IEEE Transactions on Image Processing |
Keywords | Field | DocType |
Fourier analysis,Wiener filters,image denoising,interpolation,least mean squares methods,smoothing methods,splines (mathematics),white noise,Fourier filtering,Laplace functions,MMSE estimation,fractal-like signals,fractional Brownian field,fractional iterate,fractional polyharmonic B-spline basis,linear filter,multidimensional Wiener filtering,natural images,nonuniformly sampled multidimensional data approximation,optimal interpolation space,oracle Wiener filter,polyharmonic smoothing splines,radial basis functions,regularization functional,true noiseless power spectrum,white noise,Fractal image model,multidimensional Wiener filter,optimal multidimensional linear filtering,polyharmonic smoothing splines | B-spline,Spline (mathematics),Thin plate spline,Mathematical analysis,Interpolation,Artificial intelligence,Wiener filter,Pattern recognition,Smoothing spline,Algorithm,Filter (signal processing),Smoothing,Mathematics | Journal |
Volume | Issue | ISSN |
15 | 9 | 1057-7149 |
Citations | PageRank | References |
6 | 0.76 | 22 |
Authors | ||
3 | ||
Name | Order | Citations | PageRank |
|---|---|---|---|
| Shai Tirosh | 1 | 6 | 1.10 |
| Dimitri Van De Ville | 2 | 153 | 9.80 |
| Unser, M. | 3 | 3438 | 442.40 |