Publications de Julien René Pierre Fageot

Splines Are Universal Solutions of Linear Inverse Problems with Generalized TV Regularization

Michaël Unser, Julien René Pierre Fageot, John Paul Ward

Splines come in a variety of flavors that can be characterized in terms of some differential operator L. The simplest piecewise-constant model corresponds to the derivative operator. Likewise, one can extend the traditional notion of total variation by con ...

2017

Compactly-Supported Smooth Interpolators for Shape Modeling with Varying Resolution

Michaël Unser, Pablo Garcia-Amorena Garcia, Julien René Pierre Fageot, Daniel Andreas Schmitter, Anaïs Laure Marie-Thérèse Badoual

In applications that involve interactive curve and surface modeling, the intuitive manipulation of shapes is crucial. For instance, user interaction is facilitated if a geometrical object can be manipulated through control points that interpolate the shape ...

2017

On the Besov regularity of periodic Levy noises

Michaël Unser, Julien René Pierre Fageot, John Paul Ward

In this paper, we study the Besov regularity of Levy white noises on the d-dimensional torus. Due to their rough sample paths, the white noises that we consider are defined as generalized stochastic fields. We, initially, obtain regularity results for gene ...

Academic Press Inc Elsevier Science2017

Representer Theorems for Sparsity-Promoting $ ℓ _{ 1 } $ Regularization

Michaël Unser, Julien René Pierre Fageot, Harshit Gupta

We present a theoretical analysis and comparison of the effect of

ℓ _{ 1 }

versus

ℓ _{ 2 }

regularization for the resolution of ill-posed linear inverse and/or compressed sensing problems. Our formulation covers the most general setting where the s ...

IEEE2016

Hermite Snakes with Control of Tangents

Michaël Unser, Julien René Pierre Fageot, Virginie Sophie Uhlmann

We introduce a new model of parametric contours defined in a continuous fashion. Our curve model relies on Hermite spline interpolation and can easily generate curves with sharp discontinuities; it also grants direct access to the tangent at each location. ...

IEEE2016

Statistical Optimality of Hermite Splines

Michaël Unser, Julien René Pierre Fageot, Virginie Sophie Uhlmann, Harshit Gupta

Hermite splines are commonly used for interpolating data when samples of the derivative are available, in a scheme called Hermite interpolation. Assuming a suitable statistical model, we demonstrate that this method is actually optimal for reconstructing r ...

IEEE2015

Wavelet Statistics of Sparse and Self-Similar Images

Michaël Unser, Emrah Bostan, Julien René Pierre Fageot

It is well documented that natural images are compressible in wavelet bases and tend to exhibit fractal properties. In this paper, we investigate statistical models that mimic these behaviors. We then use our models to make predictions on the statistics of ...

Siam Publications2015

Interpretation of Continuous-Time Autoregressive Processes as Random Exponential Splines

Michaël Unser, Julien René Pierre Fageot, John Paul Ward

We consider the class of continuous-time autoregressive (CAR) processes driven by (possibly non-Gaussian) Lévy white noises. When the excitation is an impulsive noise, also known as compound Poisson noise, the associated CAR process is a random non-uniform ...

IEEE2015

On the Continuity of Characteristic Functionals and Sparse Stochastic Modeling

Michaël Unser, Arash Amini, Julien René Pierre Fageot

The characteristic functional is the infinite-dimensional generalization of the Fourier transform for measures on function spaces. It characterizes the statistical law of the associated stochastic process in the same way as a characteristic function specif ...

Springer Birkhauser2014

Statistics of Wavelet Coefficients for Sparse Self-Similar Images

Michaël Unser, Emrah Bostan, Julien René Pierre Fageot

We study the statistics of wavelet coefficients of non-Gaussian images, focusing mainly on the behaviour at coarse scales. We assume that an image can be whitened by a fractional Laplacian operator, which is consistent with an

∥ω∥ ^{ -\gamma }

spectral ...

IEEE2014

Julien René Pierre Fageot

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Splines Are Universal Solutions of Linear Inverse Problems with Generalized TV Regularization

Compactly-Supported Smooth Interpolators for Shape Modeling with Varying Resolution

On the Besov regularity of periodic Levy noises

Representer Theorems for Sparsity-Promoting $ ℓ _{ 1 } $ Regularization

Hermite Snakes with Control of Tangents

Statistical Optimality of Hermite Splines

Wavelet Statistics of Sparse and Self-Similar Images

Interpretation of Continuous-Time Autoregressive Processes as Random Exponential Splines

On the Continuity of Characteristic Functionals and Sparse Stochastic Modeling

Statistics of Wavelet Coefficients for Sparse Self-Similar Images

Splines Are Universal Solutions of Linear Inverse Problems with Generalized TV Regularization

On the Besov regularity of periodic Levy noises

Hermite Snakes with Control of Tangents

Statistical Optimality of Hermite Splines

Statistics of Wavelet Coefficients for Sparse Self-Similar Images

Representer Theorems for Sparsity-Promoting $ ℓ _{ 1 } $ Regularization

Interpretation of Continuous-Time Autoregressive Processes as Random Exponential Splines

Compactly-Supported Smooth Interpolators for Shape Modeling with Varying Resolution

Wavelet Statistics of Sparse and Self-Similar Images

On the Continuity of Characteristic Functionals and Sparse Stochastic Modeling