Provably scale-covariant networks from oriented quasi quadrature measures in cascade

This article presents a continuous model for hierarchical networks based on a combination of mathematically derived models of receptive fields and biologically inspired computations. Based on a functional model of complex cells in terms of an oriented quasi quadrature combination of first- and second-order directional Gaussian derivatives, we couple such primitive computations in cascade over combinatorial expansions over image orientations. Scale-space properties of the computational primitives are analysed and it is shown that the resulting representation allows for provable scale and rotation covariance. A prototype application to texture analysis is developed and it is demonstrated that a simplified mean-reduced representation of the resulting QuasiQuadNet leads to promising experimental results on three texture datasets.Comment: 12 pages, 3 figures, 1 tabl

Enhancing music information retrieval by incorporating image-based local features

This paper presents a novel approach to Music Information Retrieval. Having represented the music tracks in the form of two dimensional images, we apply the "bag of visual words" method from visual IR in order to classify the songs into 19 genres. By switching to visual domain we can abstract from musical concepts such as melody, timbre and rhythm. We obtained classification accuracy of 46% (with 5% theoretical baseline for random classification) which is comparable with existing state-of-the-art approaches. Moreover, the novel features characterize different properties of the signal than standard methods. Therefore, the combination of them should further improve the performance of existing techniques

The use of automatic scale selection to improve the spatial and spectral resolution of a scintillator-coupled EMCCD

The technology behind the Electron-Multiplying Charge Coupled Device (EMCCD) was successfully exploited by e2v technologies in the late 1990s. Since then, many uses have been found for these low light level (L3) devices including surveillance and many scientific applications. The EMCCD increases or 'multiplies' the charge signal by the phenomenon of impact ionisation (or avalanche multiplication) allowing the detection of low signal events of only a few photons. When coupled with a scintillator, this low light capability can be used to image photon flashes from individual X-ray interaction events. The combination of depth of interaction effects in the scintillator, shot noise on the signal and the multiplication noise factor lead to large variations in the profile of the detected signal from a constant energy X-ray source. This variation leads to reduced spectral performance and can have adverse effects on the centering techniques used in photon-counting imagers. The concept of scale-space is similar in many ways to the Fourier or wavelet transforms. Automatic scale selection can be implemented through the scale-space transform as a method of fitting a known profile to the observed photon flash. The process is examined here in the context of the photon-counting EMCCD detector and the results obtained in both simulated and experimental data compared. Through the analysis of the fitting process and the results achieved, the implications on imaging performance and spectral resolution are discussed

Modeling software design diversity

Design diversity has been used for many years now as a means of achieving a degree of fault tolerance in software-based systems. Whilst there is clear evidence that the approach can be expected to deliver some increase in reliability compared with a single version, there is not agreement about the extent of this. More importantly, it remains difficult to evaluate exactly how reliable a particular diverse fault-tolerant system is. This difficulty arises because assumptions of independence of failures between different versions have been shown not to be tenable: assessment of the actual level of dependence present is therefore needed, and this is hard. In this tutorial we survey the modelling issues here, with an emphasis upon the impact these have upon the problem of assessing the reliability of fault tolerant systems. The intended audience is one of designers, assessors and project managers with only a basic knowledge of probabilities, as well as reliability experts without detailed knowledge of software, who seek an introduction to the probabilistic issues in decisions about design diversity

Compositional Design and Verification of a Multi-Agent System for One-to-Many Negotiation

A compositional verification method for multi-agent systems is presented and applied to a multi-agent system for one-to-many negotiation in the domain of load balancing of electricity use. Advantages of the method are that the complexity of the verification process is managed by compositionality, and that parts of the proofs can be reused in relation to reuse of components