Search results for " Coding"
showing 10 items of 139 documents
A new minimum spanning tree-based method for shape description and matching working in Discrete Cosine space
2009
In this article, a new minimum spanning tree-based method for shape description and matching is proposed. Its properties are checked through the problem of graphical symbols recognition. Recognition invariance in front shift and multi-oriented noisy objects was studied in the context of small and low resolution binary images. The approach seems to have many desirable properties, even if the construction of graphs induces an expensive algorithmic cost. In order to reduce time computing, an alternative solution based on image compression concepts is provided. The recognition is realized in a compact space, namely the Discrete Cosine space. The use of block discrete cosine transform is discuss…
A block access unit for 2D memory access
2007
Many of the coding tools in the H.264/AVC video coding standard are based on 2D processing resulting in rowwise and column-wise memory accesses starting from arbitrary memory addresses. This paper discusses a low-cost hardware realization of these accesses on sub-word parallel processors. The proposed block access unit is placed between the processor and memory. It supports unaligned 2D block accesses according to several 2D access patterns. The 2D block accesses are pipelinable and they result in minimum number of memory accesses required to deliver the desired data.
Statistical atmospheric parameter retrieval largely benefits from spatial-spectral image compression
2021
The infrared atmospheric sounding interferometer (IASI) is flying on board of the Metop satellite series, which is part of the EUMETSAT Polar System. Products obtained from IASI data represent a significant improvement in the accuracy and quality of the measurements used for meteorological models. Notably, the IASI collects rich spectral information to derive temperature and moisture profiles, among other relevant trace gases, essential for atmospheric forecasts and for the understanding of weather. Here, we investigate the impact of near-lossless and lossy compression on IASI L1C data when statistical retrieval algorithms are later applied. We search for those compression ratios that yield…
Automatic Biological Cell Counting Using a Modified Gradient Hough Transform
2017
AbstractWe present a computational method for pseudo-circular object detection and quantitative characterization in digital images, using the gradient accumulation matrix as a basic tool. This Gradient Accumulation Transform (GAT) was first introduced in 1992 by Kierkegaard and recently used by Kaytanli & Valentine. In the present article, we modify the approach by using the phase coding studied by Cicconet, and by adding a “local contributor list” (LCL) as well as a “used contributor matrix” (UCM), which allow for accurate peak detection and exploitation. These changes help make the GAT algorithm a robust and precise method to automatically detect pseudo-circular objects in a microscop…
Reduction of spherical-aberration impact in microscopy by wavefront coding
2009
In modern high-NA optical scanning instruments, like scanning microscopes, the refractive-index mismatch between the sample and the immersion medium introduces a significant amount of spherical aberration when imaging deep inside the specimen, spreading out the impulse response. Since such aberration depends on the focalization depth, it is not possible to achieve a static global compensation for the whole 3D sample in scanning microscopy. Therefore a depth-variant impulse response is generated. Consequently, the design of pupil elements that increase the tolerance to this aberration is of great interest. In this paper we report a hybrid technique that provides a focal spot that remains alm…
Vulnerabilities and Threats to Human Security Generated by an Ineffective Educational System
2017
Abstract The present trend towards globalization has led to people changing their views on possible threats to their existence. Nowadays, we witness a diversification of vulnerabilities and threats to human security, as well as a progressive reduction of our resilience. The article attempts to correlate the 5 dimensions of national security, as identified by the Copenhagen School of Security, with the problems of the Romanian educational system, explaining how these problems can become threats to the security of Romanian citizens. It offers an overview of the problems of the Romanian educational system, and the threats and vulnerabilities derived from them towards human security. It also su…
Comparison of perceptually uniform quantisation with average error minimisation in image transform coding
1999
An alternative transform coder design criterion based on restricting the maximum perceptual error of each coefficient is proposed. This perceptually uniform quantisation of the transform domain ensures that the perceptual error will be below a certain limit regardless of the particular input image. The results show that the proposed criterion improves the subjective quality of the conventional average error criterion even if it is weighted with the same perceptual metric.
Exosome A Clinical Compendium - Chapter 1: Exosome basic mechanisms
2019
Cell-cell communication plays a key role in maintaining homeostasis in multicellular organism. Cells communicate each other not only via the canonical pathways (cytokines, neurotransmitters, direct contact, ECM-mediated interactions or hormones) but also releasing extracellular vesicles that can reach different regions of the organism acting as a new “endocrine signalling mechanism”. Among extracellular vesicles, exosomes are emerging as efficient players to modulate target cells phenotype through the delivery to compliant receiving cells of a multitude of molecules such as mRNAs, microRNAs, long non-coding RNAs, DNA, lipids, metabolites and proteins. A deeper understanding of their content…
Working memory performance is tied to stimulus complexity
2021
1. Summary Working memory is the cognitive capability to maintain and process information over short periods. Recent behavioral and computational studies have shown that increased visual information of the presented stimulus material is associated with enhanced working memory performance. However, the underlying neural correlates of this association are unknown. To identify how stimuli of different visual information levels affect working memory performance, we conducted behavioral experiments and single unit recordings in the avian analog of the prefrontal cortex, the nidopallium caudolaterale (NCL). On the behavioral level, we confirmed that feature-rich complex stimuli demonstrated highe…
Psychophysically Tuned Divisive Normalization Approximately Factorizes the PDF of Natural Images
2010
The conventional approach in computational neuroscience in favor of the efficient coding hypothesis goes from image statistics to perception. It has been argued that the behavior of the early stages of biological visual processing (e.g., spatial frequency analyzers and their nonlinearities) may be obtained from image samples and the efficient coding hypothesis using no psychophysical or physiological information. In this work we address the same issue in the opposite direction: from perception to image statistics. We show that psychophysically fitted image representation in V1 has appealing statistical properties, for example, approximate PDF factorization and substantial mutual informatio…