Concept

Compression artifact

Publications associées (476)

Video Coding with Lifted Wavelet Transforms and Complementary Motion-Compensated Signals

This paper investigates video coding with wavelet transforms applied in the temporal direction of a video sequence. The wavelets are implemented with the lifting scheme in order to permit motion compensation between successive pictures. We improve motion c ...

SPIE2004

Distributed Coding of Dynamic Scenes with Motion-Compensated Wavelets

Pierre Vandergheynst

This paper discusses distributed coding of two correlated video signals. The video signals are captured from a dynamic scene where each signal is temporally decorrelated by a motion-compensated Haar wavelet. The two cameras operate independently, however, ...

IEEE2004

Error-Resilient Video Coding Performance Analysis of Motion JPEG 2000 and MPEG-4

Touradj Ebrahimi

The new Motion JPEG 2000 standard is providing with some compelling features. It is based on an intra-frame wavelet coding, which makes it very well suited for wireless applications. Indeed, the state-of-the-art wavelet coding scheme achieves very high cod ...

SPIE2004

On Local Features for Face Verification

{W}e compare four local feature extraction techniques for the task of face verification, namely (ordered in terms of complexity): raw pixels, raw pixels with mean removal, 2D Discrete Cosine Transform (DCT) and local Principal Component Analysis (PCA). The ...

IDIAP2004

Color image enhancement using a Retinex-based adaptive filter

Sabine Süsstrunk, Laurence Meylan

We present a new adaptation of Retinex to enhance the rendering of high dynamic range digital color images. The image is processed using an adaptive Gaussian filter. The shape of the filter basis is adapted to follow the high contrasted edges of the image. ...

2004

Towards Perceptually Driven Segmentation Evaluation Metrics

Touradj Ebrahimi, Elisa Drelie Gelasca

To be reliable, an automatic segmentation evaluation metric has to be validated by subjective tests. In this paper, a formal protocol for subjective tests for segmentation quality assessment is presented. The most common artifacts produced by segmentation ...

IEEE2004

Measuring Colourfulness in Natural Images

Sabine Süsstrunk, David Hasler

We want to integrate colourfulness in an image quality evaluation framework. This quality framework is meant to evaluate the perceptual impact of a compression algorithm or an error prone communication channel on the quality of an image. The image might go ...

2003

Very low bit rate image coding using redundant dictionaries

Pierre Vandergheynst, Lorenzo Granai, Lorenzo Peotta

Very low bit rate image coding is an important problem regarding applications such as storage on low memory devices or streaming data on the internet. The state of the art in image compression is to use 2-D wavelets. The advantages of wavelet bases lie in ...

SPIE2003

Low rate and scalable image coding with redundant representations

Pascal Frossard, Pierre Vandergheynst

New breakthroughs in image coding possibly rely in signal decomposition through non-separable basis functions. The work proposed in this paper provides an adaptive way of representing images as a sum of two-dimensional features. It presents a low bit-rate ...

2003

Robust Features for Frontal Face Authentication in Difficult Image Conditions

Samy Bengio

In this report we extend the recently proposed {DCT}-mod2 feature extraction technique (which utilizes polynomial coefficients derived from {2D} {DCT} coefficients obtained from horizontally & vertically neighbouring blocks) via the use of various windows ...

IDIAP2003

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