A separate least squares algorithm for efficient arithmetic coding in lossless image compression

The overall performance of discrete wavelet transforms for losssless image compression may be further improved by properly designing efficient entropy coders. In this paper a novel technique is proposed for the implementation of context-based adaptive arithmetic entropy coding. It is based on the prediction of the value of the current transform coefficient. The proposed algorithm employs a weighted least squares method applied separately for the HH, HL and LH bands of each level of the multiresolution structure, in order to achieve appropriate context selection for arithmetic coding. Experimental results illustrate and evaluate the performance of the proposed technique for lossless image compression

Advanced content-based semantic scene analysis and information retrieval: the SCHEMA project

The aim of the SCHEMA Network of Excellence is to bring together a critical mass of universities, research centers, industrial partners and end users, in order to design a reference system for content-based semantic scene analysis, interpretation and understanding. Relevant research areas include: content-based multimedia analysis and automatic annotation of semantic multimedia content, combined textual and multimedia information retrieval, semantic -web, MPEG-7 and MPEG-21 standards, user interfaces and human factors. In this paper, recent advances in content-based analysis, indexing and retrieval of digital media within the SCHEMA Network are presented. These advances will be integrated in the SCHEMA module-based, expandable reference system

Revisiting QRS detection methodologies for portable, wearable, battery-operated, and wireless ECG systems

Cardiovascular diseases are the number one cause of death worldwide. Currently, portable battery-operated systems such as mobile phones with wireless ECG sensors have the potential to be used in continuous cardiac function assessment that can be easily integrated into daily life. These portable point-of-care diagnostic systems can therefore help unveil and treat cardiovascular diseases. The basis for ECG analysis is a robust detection of the prominent QRS complex, as well as other ECG signal characteristics. However, it is not clear from the literature which ECG analysis algorithms are suited for an implementation on a mobile device. We investigate current QRS detection algorithms based on three assessment criteria: 1) robustness to noise, 2) parameter choice, and 3) numerical efficiency, in order to target a universal fast-robust detector. Furthermore, existing QRS detection algorithms may provide an acceptable solution only on small segments of ECG signals, within a certain amplitude range, or amid particular types of arrhythmia and/or noise. These issues are discussed in the context of a comparison with the most conventional algorithms, followed by future recommendations for developing reliable QRS detection schemes suitable for implementation on battery-operated mobile devices.Mohamed Elgendi, Björn Eskofier, Socrates Dokos, Derek Abbot

Algorithms and structures for convolutions over Galois fields

Le calcul des convolutions cycliques dans des Corps de Galois est une partie intégrante aussi bien de la théorie et de la formulation de Codage, que de nombreuses applications de Traitement du Signal, Dans le travail présent nous introduisons une méthode pour le calcul des convolutions de ce genre, qui minimise, en théorie, la complexité des calculs de l'algorithme. Nous proposons également des structures d' ordinateur pour la réalisation efficace de 1' algorithme, et en général pour le calcul efficace des convolutions dans des Corps de Galois. I.Introduction As is well known [1-5] both cyclic and non-cyclic convolutions in Galois Fields are instrumental for the solution of several Signal Processing [2,9] and many Coding and Decoding Problems [5,6]. For instance cyclic convolutions in Galois Fields are needed for the decoding of among others, the BCH (Bose-Chaudhuri-Hohequem) and the Reed-Solomon codes [5,6]. In the following, GF(p) (where p is a prime integer) will be understood to denote the Galois Field with elements {0,1,..p-1}, and GF(pn) = GF(p,fn (x)) the Galois Field generated by the nth degree-polynomial fn(x) and composed of all polynomials with degree no greater than n and coefficients in GF(p). In GF(pn) multiplication of its element polynomials is defined modulo fn(x) and addition of the coefficients of the polynomials is defined modulo p

A Separate Least Squares Algorithm for Efficient Arithmetic Coding in Lossless Image Compression

The overall performance of discrete wavelet transforms for lossless image compression may be further improved by properly designing efficient entropy coders. In this paper a novel technique is proposed for the implementation of context-based adaptive arith-metic entropy coding. It is based on the prediction of the value of the current transform coefficient. The proposed algorithm employs a weighted least squares method applied separately for the HH, HL and LH bands of each level of the multiresolution structure, in order to achieve appropriate context selection for arithmetic coding. Experimental re-sults illustrate and evaluate the performance of the proposed technique for lossless image compression