Publications by Patrick Vandewalle

Reproducible Research in Signal Processing - What, why, and how

Have you ever tried to reproduce the results presented in a research paper? For many of our current publications, this would unfortunately be a challenging task. For a computational algorithm, details such as the exact data set, initialization or terminati ...

Institute of Electrical and Electronics Engineers2009

Groebner Basis Methods for Multichannel Sampling with Unknown Offsets

Martin Vetterli, Luciano Sbaiz, Patrick Vandewalle

In multichannel sampling, several sets of sub-Nyquist sampled signal values are acquired. The offsets between the sets are unknown, and have to be resolved, just like the parameters of the signal itself. This problem is nonlinear in the offsets, but linear ...

Elsevier2008

Subspace-Based Methods for Image Registration and Super-Resolution

Martin Vetterli, Pier Luigi Dragotti, Loïc Arnaud Baboulaz, Patrick Vandewalle

Super-resolution algorithms combine multiple low resolution images into a single high resolution image. They have received a lot of attention recently in various application domains such as HDTV, satellite imaging, and video surveillance. These techniques ...

2008

The Flux: Creating a Large Annotated Image Database

Daniel Tamburrino, Sabine Süsstrunk, Patrick Vandewalle, Patrick Merryl Marlon Schönmann

From image retrieval to image classification, all research shares one common requirement: a good image database to test or train the algorithms. In order to create a large database of images, we set up a project that allowed gathering a collection of more ...

2008

Super-Resolution from Unregistered and Totally Aliased Signals Using Subspace Methods

Martin Vetterli, Luciano Sbaiz, Patrick Vandewalle

In many applications, the sampling frequency is limited by the physical characteristics of the components: the pixel pitch, the rate of the A/D converter, etc. A low-pass filter is then often applied before the sampling operation to avoid aliasing. However ...

Institute of Electrical and Electronics Engineers2007

Multidimensional image enhancement from a set of unregistered differently exposed images

Laurence Meylan, Sabine Süsstrunk, Patrick Vandewalle, Ali Ajdari Rad

If multiple images of a scene are available instead of a single image, we can use the additional information conveyed by the set of images to generate a higher quality image. This can be done along multiple dimensions. Super-resolution algorithms use a set ...

2007

Experiences with Reproducible Research in Various Facets of Signal Processing Research

Martin Vetterli, Patrick Vandewalle, Guillermo Barrenetxea Kobas, Andrea Ridolfi, Ivana Jovanovic

How often have you been able to implement an algorithm as it is described in a paper? And when you did, were you confident that you had exactly the same parameter values and results as the authors of the paper? All too often, articles do not describe all t ...

2007

Joint Demosaicing and Super-Resolution Imaging from a Set of Unregistered Aliased Images

Sabine Süsstrunk, Patrick Vandewalle, Karim Krichane

We present a new algorithm that performs demosaicing and super-resolution jointly from a set of raw images sampled with a color filter array. Such a combined approach allows us to compute the alignment parameters between the images on the raw camera data b ...

2007

Registration of Aliased Images for Super-Resolution Imaging

Martin Vetterli, Luciano Sbaiz, Sabine Süsstrunk, Patrick Vandewalle

Super-resolution imaging techniques reconstruct a high resolution image from a set of low resolution images that are taken from almost the same point of view. The problem can be subdivided into two main parts: an image registration part where the different ...

2006

Signal Reconstruction from Multiple Unregistered Sets of Samples using Groebner Bases

Martin Vetterli, Luciano Sbaiz, Patrick Vandewalle

We present a new method for signal reconstruction from multiple sets of samples with unknown offsets. We rewrite the reconstruction problem as a set of polynomial equations in the unknown signal parameters and the offsets between the sets of samples. Then, ...

2006

Super-resolution from unregistered aliased images

Patrick Vandewalle

Aliasing in images is often considered as a nuisance. Artificial low frequency patterns and jagged edges appear when an image is sampled at a too low frequency. However, aliasing also conveys useful information about the high frequency content of the image ...

EPFL2006

A Frequency Domain Approach to Registration of Aliased Images with Application to Super-Resolution

Martin Vetterli, Sabine Süsstrunk, Patrick Vandewalle

Super-resolution algorithms reconstruct a high resolution image from a set of low resolution images of a scene. Precise alignment of the input images is an essential part of such algorithms. If the low resolution images are undersampled and have aliasing a ...

2006

Automatic Red-Eye Removal based on Sclera and Skin Tone Detection

Patrick Vandewalle, Flavien Volken, Johann Terrier

It is well-known that taking portrait photographs with a built in camera may create a red-eye effect. This effect is caused by the light entering the subject’s eye through the pupil and reflecting from the retina back to the sensor. These red eyes are prob ...

2006

Super-Resolution from Highly Undersampled Images

Martin Vetterli, Luciano Sbaiz, Sabine Süsstrunk, Patrick Vandewalle

Aliasing artifacts in images are visually very disturbing. Therefore, most imaging devices apply a low-pass filter before sampling. This removes all aliasing from the image, but it also creates a blurred image. Actually, all the image information above hal ...

2005