Publication

Fractional Derivatives, Splines and Tomography

Related publications (46)

Multiwavelet-Like Bases for High Quality Image Interpolation

We present a simple but generalized interpolation method for digital images that uses multiwavelet-like basis functions. Most of interpolation methods uses only one symmetric basis function; for example, standard and shifted piecewise-linear interpolations ...

SPIE2003

Recursive Filtering for Splines on Hexagonal Lattices

Michaël Unser, Dimitri Nestor Alice Van De Ville, Thierry Blu

Hex-splines are a novel family of bivariate splines, which are well suited to handle hexagonally sampled data. Similar to classical 1D B-splines, the spline coefficients need to be computed by a prefilter. Unfortunately, the elegant implementation of this ...

IEEE2003

Filter Design for Filtered Back-Projection Guided by the Interpolation Model

Michaël Unser

We consider using spline interpolation to improve the standard filtered back-projection (FBP) tomographic reconstruction algorithm. In particular, we propose to link the design of the filtering operator with the interpolation model that is applied to the s ...

SPIE2002

Splines: A Perfect Fit for Medical Imaging

Michaël Unser

Splines, which were invented by Schoenberg more than fifty years ago, constitute an elegant framework for dealing with interpolation and discretization problems. They are widely used in computer-aided design and computer graphics, but have been neglected i ...

SPIE2002

Discretization of the radon transform and of its inverse by spline convolutions

Michaël Unser, Michael Stefan Daniel Liebling, Stefan Horbelt

We present an explicit formula for B-spline convolution kernels; these are defined as the convolution of several B-splines of variable widths hi and degrees ni. We apply our results to derive spline-convolution-based algorithms for two closely related prob ...

IEEE2002

Why Restrict Ourselves to Compactly Supported Basis Functions?

Michaël Unser, Thierry Blu

Compact support is undoubtedly one of the wavelet properties that is given the greatest weight both in theory and applications. It is usually believed to be essential for two main reasons: (1) to have fast numerical algorithms, and (2) to have good time or ...

SPIE2001

Fractional derivatives, splines and tomography

Michaël Unser, Thierry Blu, Stefan Horbelt

We develop a spline calculus for dealing with fractional derivatives. After a brief review of fractional splines, we present the main formulas for computing the fractional derivatives of the underlying basis functions. In particular, we show that the $ γ ^ ...

2000

Spline Kernels for Continuous-Space Image Processing

Michaël Unser, Thierry Blu

We present an explicit formula for spline kernels; these are defined as the convolution of several B-splines of variable widths h and degrees n. The spline kernels are useful for continuous signal processing algorithms that involve B-spline inner-products ...

IEEE2000

Interpolation Revisited

Michaël Unser, Philippe Thévenaz, Thierry Blu

Based on the theory of approximation, this paper presents a unified analysis of interpolation and resampling techniques. An important issue is the choice of adequate basis functions. We show that, contrary to the common belief, those that perform best are ...

IEEE2000

Complete Parametrization of Piecewise-Polynomial Interpolators According to Degree, Support, Regularity, and Order

Michaël Unser, Philippe Thévenaz, Thierry Blu

The most essential ingredient of interpolation is its basis function. We have shown in previous papers that this basis need not be necessarily interpolating to achieve good results. On the contrary, several recent studies have confirmed that non-interpolat ...

IEEE2000

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