Publications related to Directionlets

Sparse Image Representation by Directionlets

Martin Vetterli, Vladan Velisavljevic, Pier Luigi Dragotti

Despite the success of the standard wavelet transform (WT) in image processing in recent years, the efficiency and sparsity of its representation are limited by the spatial symmetry and separability of its basis functions built in the horizontal and vertic ...

Elsevier2010

Sensing and Recovery under Sparsity Constraints

Ali Hormati

Popular transforms, like the discrete cosine transform or the wavelet transform, owe their success to the fact that they promote sparsity. These transforms are capable of extracting the structure of a large class of signals and representing them by a few t ...

EPFL2010

Low bit-rate compression of omnidirectional images

Pascal Frossard, Ivana Tosic

Omnidirectional images represent a special type of images that are captured by vision sensors with a 360-degree field of view. This work targets the compression of such images by taking into account their particular geometry. We first map omnidirectional i ...

2009

Bit Rate Allocation for Disparity Estimation from Compressed Images

Pascal Frossard, Vijayaraghavan Thirumalai

This paper presents a novel rate allocation scheme to compute the 3D structure of the scene from compressed stereo images, captured by the distributed vision sensor networks. The images captured at different view points are encoded independently with a bal ...

2009

Wavelet-Regularized Reconstruction for Rapid MRI

Michaël Unser, Dimitri Nestor Alice Van De Ville, Cédric René Jean Vonesch, Matthieu Guerquin-Kern, Jean-Charles Baritaux

We propose a reconstruction scheme adapted to MRI that takes advantage of a sparsity constraint in the wavelet domain. We show that artifacts are significantly reduced compared to conventional reconstruction methods. Our approach is also competitive with ...

IEEE2009

A Fast Thresholded Landweber Algorithm for Wavelet-Regularized Multidimensional Deconvolution

Michaël Unser, Cédric René Jean Vonesch

We present a fast variational deconvolution algorithm that minimizes a quadratic data term subject to a regularization on the

\ell ^{ 1 }

-norm of the wavelet coefficients of the solution. Previously available methods have essentially consisted in alte ...

IEEE2008

Space-frequency quantization for image compression with directionlets

Martin Vetterli, Vladan Velisavljevic

The standard separable 2-D wavelet transform (WT) has recently achieved a great success in image processing because it provides a sparse representation of smooth images. However, it fails to efficiently capture 1-D discontinuities, like edges or contours. ...

2007

Algorithms and methods for sparse approximation in structured dictionaries

Lorenzo Peotta

In the last decade we observed an increasing interaction between data compression and sparse signals approximations. Sparse approximations are desirable because they compact the energy of the signals in few elements and correspond to a structural simplific ...

EPFL2007

A Generalization of the Finite-Length Scaling Approach Beyond the BEC

Rüdiger Urbanke, Jérémie Ezri

We want to extend the approximation of the error probability via a scaling approach from the BEC to general binary-input memoryless output-symmetric (BMS) channels. In particular, we consider such scaling laws for regular LDPC ensembles and message-passing ...

2007

A fast iterative thresholding algorithm for wavelet-regularized deconvolution - art. no. 67010D

Michaël Unser, Cédric René Jean Vonesch

We present an iterative deconvolution algorithm that minimizes a functional with a non-quadratic wavelet-domain regularization term. Our approach is to introduce subband-dependent parameters into the bound optimization framework of Daubechies et al.; it is ...

Spie-Int Soc Optical Engineering, Po Box 10, Bellingham, Wa 98227-0010 Usa2007

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Sparse Image Representation by Directionlets

Sensing and Recovery under Sparsity Constraints

Low bit-rate compression of omnidirectional images

Bit Rate Allocation for Disparity Estimation from Compressed Images

Wavelet-Regularized Reconstruction for Rapid MRI

A Fast Thresholded Landweber Algorithm for Wavelet-Regularized Multidimensional Deconvolution

Space-frequency quantization for image compression with directionlets

Algorithms and methods for sparse approximation in structured dictionaries

A Generalization of the Finite-Length Scaling Approach Beyond the BEC

A fast iterative thresholding algorithm for wavelet-regularized deconvolution - art. no. 67010D

Sparse Image Representation by Directionlets

Sensing and Recovery under Sparsity Constraints

Low bit-rate compression of omnidirectional images

Space-frequency quantization for image compression with directionlets

A Fast Thresholded Landweber Algorithm for Wavelet-Regularized Multidimensional Deconvolution

Algorithms and methods for sparse approximation in structured dictionaries

A Generalization of the Finite-Length Scaling Approach Beyond the BEC

A fast iterative thresholding algorithm for wavelet-regularized deconvolution - art. no. 67010D

Wavelet-Regularized Reconstruction for Rapid MRI

Bit Rate Allocation for Disparity Estimation from Compressed Images