1,720,964 research outputs found
Region based compression of multispectral images by classified KLT
Full text linkPublication in the conference proceedings of EUSIPCO, Florence, Italy, 200
A SPIHT-like image coder based on the contourlet transform
No full textThe contourlet transform was recently proposed to overcome the limited ability of wavelet to represent image edges and discontinuities. Besides retaining the desirable characteristics of wavelet transform, such as multiresolution and localization, it has two additional important features: directionality and anisotropy. In this work we propose a new image coding technique based on an hybrid contourlet-wavelet decomposition. The encoder builds upon the well-known SPIHT algorithm, which is suitably modified to take into account the new hierarchical structure of the transform coefficients and the correlation between them. Both numerical results and visual quality confirm the potential of this approach, especially for images with high texture content
Adaptive region-based compression of multispectral images
No full textAbstract- The region-based description of multispectral images enables important high-level tasks such as data mining and retrieval, and region-of-interest selection. In order to obtain an efficient representation of such images we resort to adaptive transform coding techniques. Such techniques, however, require a considerable information overhead, which must be carefully managed to obtain a satisfactory rate-distortion performance. In this work we develop several region based coding schemes and compare them with conventional (non-adaptive) and class-based schemes, so as to single out the rate-distortion gains/losses of this approach
On the influence of denoising in PRNU based forgery detection
No full textTo detect some image forgeries one can rely on the Photo-Response Non-Uniformity (PRNU), a deterministic pattern associated with each individual camera, which can be loosely modeled as a low-intensity multiplicative noise.
A very promising algorithm for PRNU-based forgery detection has been recently proposed by Chen et al.[3].
Image denoising is a key step of the algorithm, since it allows to single out and remove most of the signal components and reveal the PRNU pattern.
In this work we analyze the influence of denoising on the overall performance of the method and show that the use of a suitable state-of-the art denoising technique improves performance appreciably w.r.t. the original algorithm
Sigmoid shrinkage for BM3D denoising algorithm
No full textIn this work we propose a modified version of the BM3D algorithm recently introduced by Dabov et al. [1] for the denoising of images corrupted by additive white gaussian noise.
The original technique performs a multipoint filtering, where the nonlocal approach is combined with the wavelet shrinkage of a 3D cube composed by similar patches collected by means of block-matching.
Our improvement concerns the thresholding of wavelet coefficients, which are subject to a different shrinkage depending on their level of sparsity.
The modified algorithm is more robust with respect to block matching errors, especially when noise is high, as proved by experimental results on a large set of natural images
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
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