"This book provides a comprehensive reference for the many different types and methods of compression. Included are a detailed and helpful taxonomy, analysis of most common methods, and discussions ...on the use and comparative benefits of methods and description of ""how to"" use them. Detailed descriptions and explanations of the most well-known and frequently used compression methods are covered in a self-contained fashion, with an accessible style and technical level for specialists and nonspecialists. This 4th edition of this successful volume contains significant additional material as there has been tremendous progress in this field, especially in audio compression such as FLAC, AAC, WavPack, ALS and Dolby AC3, which are all covered. Additional key features include: RAR, Tunstall code, Differential and Hyperspectral Compression, LZMA, H.264, 3D data sets, PDF. This book provides an invaluable reference and guide for all researchers and practitioners needing a comprehensive compilation for a broad range of compression methods."
In recent years, image encryption has been broadly researched. Since a large proportion of images on Internet are compressed, and JPEG is the most widely adopted standards for image compression, a ...variety of joint image compression and encryption algorithms have been proposed. JPEG image encryption uses signal processing techniques as well as cryptographic techniques in different stages of the JPEG compression process. Based on the location where the encryption is taken place, these algorithms can be generally classified into three major categories: pre-compression encryption algorithms, in-compression encryption algorithms, and post-compression encryption algorithms, which correspond to conduct encryption operations before, during, and after the compression process. From this perspective of classification, the authors give a comprehensive survey on representative image encryption algorithms of each type, and show their properties and limitations. Some of the most recent encryption schemes that achieve protection at various positions of the compression process are selected for comparison, which are two pre-compression encryption algorithms, four in-compression encryption algorithms, and two post-compression encryption algorithms. Possible future research directions on designing joint JPEG compression and encryption schemes are provided in the end, which may facilitate solving application scenario-oriented JPEG security problems with new technologies.
55% new material in the latest edition of this "must-have" for students and practitioners of image & video processing!This Handbook is intended to serve as the basic reference point on image and ...video processing, in the field, in the research laboratory, and in the classroom. Each chapter has been written by carefully selected, distinguished experts specializing in that topic and carefully reviewed by the Editor, Al Bovik, ensuring that the greatest depth of understanding be communicated to the reader. Coverage includes introductory, intermediate and advanced topics and as such, this book serves equally well as classroom textbook as reference resource. . Provides practicing engineers and students with a highly accessible resource for learning and using image/video processing theory and algorithms . Includes a new chapter on image processing education, which should prove invaluable for those developing or modifying their curricula . Covers the various image and video processing standards that exist and are emerging, driving today's explosive industry . Offers an understanding of what images are, how they are modeled, and gives an introduction to how they are perceived . Introduces the necessary, practical background to allow engineering students to acquire and process their own digital image or video data . Culminates with a diverse set of applications chapters, covered in sufficient depth to serve as extensible models to the reader's own potential applications About the Editor. Al Bovik is the Cullen Trust for Higher Education Endowed Professor at The University of Texas at Austin, where he is the Director of the Laboratory for Image and Video Engineering (LIVE). He has published over 400 technical articles in the general area of image and video processing and holds two U.S. patents. Dr. Bovik was Distinguished Lecturer of the IEEE Signal Processing Society (2000), received the IEEE Signal Processing Society Meritorious Service Award (1998), the IEEE Third Millennium Medal (2000), and twice was a two-time Honorable Mention winner of the international Pattern Recognition Society Award. He is a Fellow of the IEEE, was Editor-in-Chief, of the IEEE Transactions on Image Processing (1996-2002), has served on and continues to serve on many other professional boards and panels, and was the Founding General Chairman of the IEEE International Conference on Image Processing which was held in Austin, Texas in 1994.
* No other resource for image and video processing contains the same breadth of up-to-date coverage* Each chapter written by one or several of the top experts working in that area* Includes all essential mathematics, techniques, and algorithms for every type of image and video processing used by electrical engineers, computer scientists, internet developers, bioengineers, and scientists in various, image-intensive disciplines
A huge amount of data is acquired nowadays by different remote sensing systems installed on satellites, aircrafts, and UAV. The acquired data then have to be transferred to image processing centres, ...stored and/or delivered to customers. In restricted scenarios, data compression is strongly desired or necessary. A wide diversity of coding methods can be used, depending on the requirements and their priority. In addition, the types and properties of images differ a lot, thus, practical implementation aspects have to be taken into account. The Special Issue paper collection taken as basis of this book touches on all of the aforementioned items to some degree, giving the reader an opportunity to learn about recent developments and research directions in the field of image compression. In particular, lossless and near-lossless compression of multi- and hyperspectral images still remains current, since such images constitute data arrays that are of extremely large size with rich information that can be retrieved from them for various applications. Another important aspect is the impact of lossless compression on image classification and segmentation, where a reasonable compromise between the characteristics of compression and the final tasks of data processing has to be achieved. The problems of data transition from UAV-based acquisition platforms, as well as the use of FPGA and neural networks, have become very important. Finally, attempts to apply compressive sensing approaches in remote sensing image processing with positive outcomes are observed. We hope that readers will find our book useful and interesting
Only vertex chain code can be applied to triangular grids, but it has defect in angle adjacent expression. Aimed at the problem of object border representation in triangular grid, three novel chain ...codes were proposed and compared in character and performance. Firstly, Freeman chain code was extended to triangular grids. For two different triangular elements, the corresponding 12-direction Freeman chain code encoding rules were designed respectively. Secondly, based on the relative direction changes of the contour, the relative direction chain code was proposed. Finally, the edge chain code could be obtained by differentiating the combinations of edges number and internal grids number of the boundary grids. The geometric properties, expressive abilities and compression ratios of three novel chain codes were compared and analyzed. Experiments show that the proposed methods can accurately and completely realize the shape boundary expression of triangular grids. Among them, edge chain owns the best performance, the average code number per grid is 1, and compression ratio can reach 0.75.
Purpose Several parallel transmit MRI techniques require knowledge of the transmit radiofrequency field profiles (B sub(1) super(+)). During the past years, various methods have been developed to ...acquire this information. Often, these methods suffer from long measurement times and produce maps exhibiting regions with poor signal-to-noise ratio and artifacts. In this article, a model-based reconstruction procedure is introduced that improves the robustness of B sub(1) super(+) mapping. Theory and Methods The missing information from undersampled B sub(1) super(+) maps and the regions of poor signal to noise ratio are reconstructed through projection into the space of spherical functions that arise naturally from the solution of the Helmholtz equations in the spherical coordinate system. Results As a result, B sub(1) super(+) data over a limited range of the field of view/volume is sufficient to reconstruct the B sub(1) super(+) over the full spatial domain in a fast and robust way. The same model is exploited to filter the noise of the measured maps. Results from simulations and in vivo measurements confirm the validity of the proposed method. Conclusion A spherical functions model can well approximate the magnetic fields inside the body with few basis terms. Exploiting this compression capability, B sub(1) super(+) maps are reconstructed in regions of unknown or corrupted values. Magn Reson Med 71:394-401, 2014. copyright 2013 Wiley Periodicals, Inc.
This paper describes a highly efficient method for lossless compression of volumetric sets of medical images, such as CTs or MRIs. The proposed method, referred to as 3-D-MRP, is based on the ...principle of minimum rate predictors (MRPs), which is one of the state-of-the-art lossless compression technologies presented in the data compression literature. The main features of the proposed method include the use of 3-D predictors, 3-D-block octree partitioning and classification, volume-based optimization, and support for 16-b-depth images. Experimental results demonstrate the efficiency of the 3-D-MRP algorithm for the compression of volumetric sets of medical images, achieving gains above 15% and 12% for 8- and 16-bit-depth contents, respectively, when compared with JPEG-LS, JPEG2000, CALIC, and HEVC, as well as other proposals based on the MRP algorithm.
Background
Leg ulcers are open skin wounds on the lower leg that can last weeks, months or even years. Most leg ulcers are the result of venous diseases. First‐line treatment options often include ...the use of compression bandages or stockings.
Objectives
To assess the effects of using compression bandages or stockings, compared with no compression, on the healing of venous leg ulcers in any setting and population.
Search methods
In June 2020 we searched the Cochrane Wounds Specialised Register, the Cochrane Central Register of Controlled Trials (CENTRAL), Ovid MEDLINE (including In‐Process & Other Non‐Indexed Citations), Ovid Embase and EBSCO CINAHL Plus. We also searched clinical trials registries for ongoing and unpublished studies, and scanned reference lists of relevant included studies as well as reviews, meta‐analyses and health technology reports to identify additional studies. There were no restrictions by language, date of publication or study setting.
Selection criteria
We included randomised controlled trials that compared any types of compression bandages or stockings with no compression in participants with venous leg ulcers in any setting.
Data collection and analysis
At least two review authors independently assessed studies using predetermined inclusion criteria. We carried out data extraction, and risk‐of‐bias assessment using the Cochrane risk‐of‐bias tool. We assessed the certainty of the evidence according to GRADE methodology.
Main results
We included 14 studies (1391 participants) in the review. Most studies were small (median study sample size: 51 participants). Participants were recruited from acute‐care settings, outpatient settings and community settings, and a large proportion (65.9%; 917/1391) of participants had a confirmed history or clinical evidence of chronic venous disease, a confirmed cause of chronic venous insufficiency, or an ankle pressure/brachial pressure ratio of greater than 0.8 or 0.9. The average age of participants ranged from 58.0 to 76.5 years (median: 70.1 years). The average duration of their leg ulcers ranged from 9.0 weeks to 31.6 months (median: 22.0 months), and a large proportion of participants (64.8%; 901/1391) had ulcers with an area between 5 and 20 cm2. Studies had a median follow‐up of 12 weeks. Compression bandages or stockings applied included short‐stretch bandage, four‐layer compression bandage, and Unna's boot (a type of inelastic gauze bandage impregnated with zinc oxide), and comparator groups used included 'usual care', pharmacological treatment, a variety of dressings, and a variety of treatments where some participants received compression (but it was not the norm). Of the 14 included studies, 10 (71.4%) presented findings which we consider to be at high overall risk of bias.
Primary outcomes
There is moderate‐certainty evidence (downgraded once for risk of bias) (1) that there is probably a shorter time to complete healing of venous leg ulcers in people wearing compression bandages or stockings compared with those not wearing compression (pooled hazard ratio for time‐to‐complete healing 2.17, 95% confidence interval (CI) 1.52 to 3.10; I2 = 59%; 5 studies, 733 participants); and (2) that people treated using compression bandages or stockings are more likely to experience complete ulcer healing within 12 months compared with people with no compression (10 studies, 1215 participants): risk ratio for complete healing 1.77, 95% CI 1.41 to 2.21; I2 = 65% (8 studies with analysable data, 1120 participants); synthesis without meta‐analysis suggests more completely‐healed ulcers in compression bandages or stockings than in no compression (2 studies without analysable data, 95 participants).
It is uncertain whether there is any difference in rates of adverse events between using compression bandages or stockings and no compression (very low‐certainty evidence; 3 studies, 585 participants).
Secondary outcomes
Moderate‐certainty evidence suggests that people using compression bandages or stockings probably have a lower mean pain score than those not using compression (four studies with 859 participants and another study with 69 ulcers): pooled mean difference −1.39, 95% CI −1.79 to −0.98; I2 = 65% (two studies with 426 participants and another study with 69 ulcers having analysable data); synthesis without meta‐analysis suggests a reduction in leg ulcer pain in compression bandages or stockings, compared with no compression (two studies without analysable data, 433 participants). Compression bandages or stockings versus no compression may improve disease‐specific quality of life, but not all aspects of general health status during the follow‐up of 12 weeks to 12 months (four studies with 859 participants; low‐certainty evidence).
It is uncertain if the use of compression bandages or stockings is more cost‐effective than not using them (three studies with 486 participants; very low‐certainty evidence).
Authors' conclusions
If using compression bandages or stockings, people with venous leg ulcers probably experience complete wound healing more quickly, and more people have wounds completely healed. The use of compression bandages or stockings probably reduces pain and may improve disease‐specific quality of life. There is uncertainty about adverse effects, and cost effectiveness.
Future research should focus on comparing alternative bandages and stockings with the primary endpoint of time to complete wound healing alongside adverse events including pain score, and health‐related quality of life, and should incorporate cost‐effectiveness analysis where possible. Future studies should adhere to international standards of trial conduct and reporting.
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