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—In this paper, we analyse two well-known objective image quality metrics, the peak-signal-to-noise ratio (PSNR) as well as the structural similarity index measure (SSIM), and we derive a simple mathematical relationship between them which works for various kinds of image degradations such as Gaussian blur, additive Gaussian white noise, jpeg and jpeg2000(More)
In computer vision and image processing, edge detection concerns the localization of signiicant variations of the grey level image and the identiication of the physical phenomena that originated them. This information is very useful for applications in 3D diierentiation of the image. Diierentiation is an ill-conditioned problem and smoothing results in a(More)
With the explosive growth of the World Wide Web, the public is gaining access to massive amounts of information. However, locating needed and relevant information remains a difficult task, whether the information is textual or visual. Text search engines have existed for some years now and have achieved a certain degree of success. However, despite the(More)
This paper presents an unsupervised algorithm for learning a finite mixture model from multivariate data. This mixture model is based on the Dirichlet distribution, which offers high flexibility for modeling data. The proposed approach for estimating the parameters of a Dirichlet mixture is based on the maximum likelihood (ML) and Fisher scoring methods.(More)
This paper presents an unsupervised approach for feature selection and extraction in mixtures of generalized Dirichlet (GD) distributions. Our method defines a new mixture model that is able to extract independent and non-Gaussian features without loss of accuracy. The proposed model is learned using the expectation-maximization algorithm by minimizing the(More)
We consider the problem of determining the structure of high-dimensional data without prior knowledge of the number of clusters. Data are represented by a finite mixture model based on the generalized Dirichlet distribution. The generalized Dirichlet distribution has a more general covariance structure than the Dirichlet distribution and offers high(More)
It has been shown that humans use some perceptual tex­ tural features such as coarseness, contrast and direction to distinguish beMeen textured images or regions. The aim of this paper is to present a new method to estimate these perceptual textural features using the autocovariancefunc­ tion. Computational measures derivedfrom the autocovari­ ance function(More)