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A fast algorithm for constructing nearly optimal prefix codes

SOFTWARE-PRACTICE & EXPERIENCE 2016年第10期46卷 1299-1316页

作者： Osorio, Roberto R. Gonzalez, Patricia Univ A Coruna Dept Elect & Syst La Coruna 15011 Spain

huffman algorithm allows for constructing optimal prefix-codes with O(nlogn) complexity. As the number of symbols ngrows, so does the complexity of building the code-words. In this paper, a new algorithm and implementation are proposed that achieve nearly optimal coding without sorting the probabilities or building a tree of codes. The complexity is proportional to the maximum code length, making the algorithm especially attractive for large alphabets. The focus is put on achieving almost optimal coding with a fast implementation, suitable for real-time compression of large volumes of data. A practical case example about checkpoint files compression is presented, providing encouraging results. Copyright (c) 2015 John Wiley & Sons, Ltd.

关键词： data compression prefix-codes huffman algorithm

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A Lossless hybrid wavelet-fractal compression for welding radiographic images

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JOURNAL OF X-RAY SCIENCE AND TECHNOLOGY 2016年第1期24卷 107-118页

作者： Mekhalfa, Faiza Avanaki, Mohammad R. N. Berkani, Daoud Ecole Natl Polytech Dept Elect El Harrach 16200 Algeria Res Ctr Ind Technol CRTI POB 64 Algiers 16014 Algeria Wayne State Univ Dept Biomed Engn Detroit MI USA

In this work a lossless wavelet-fractal image coder is proposed. The process starts by compressing and decompressing the original image using wavelet transformation and fractal coding algorithm. The decompressed image is removed from the original one to obtain a residual image which is coded by using huffman algorithm. Simulation results show that with the proposed scheme, we achieve an infinite peak signal to noise ratio (PSNR) with higher compression ratio compared to typical lossless method. Moreover, the use of wavelet transform speeds up the fractal compression algorithm by reducing the size of the domain pool. The compression results of several welding radiographic images using the proposed scheme are evaluated quantitatively and compared with the results of huffman coding algorithm.

关键词： Fractal image compression wavelet-fractal coder lossless wavelet-fractal compression huffman algorithm radiographic images of weld defects

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Lossy Image Compression by Rounding the Intensity Followed by Dividing (RIFD)

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Research Journal of Applied Sciences, Engineering and Technology 2016年第6期12卷 680-685页

作者： M.A. Otair F. Shehadeh Faculty of Computer Sciences and Informatics Amman Arab University 11953 Amman Jordan

Several millions of digital images are transmitted every minute via mobile applications. The main feature of these images is their huge sizes. However, most of their details are not important such as natural images. Continuous efforts are achieved to utilize the wireless bandwidth and capacity for mobile users. One of the most significant efforts is the image compression. The aim of this study is to introduce a new lossy technique called RFID for compressing images, in order to overcome these problems by achieving high compression ratio. The proposed technique depends on increasing the redundancy and similarity among the neighboring pixels of images by rounding the pixels’ intensities followed by the dividing process, which makes compression feasible. It can be applied alone or followed by any lossless compression algorithm. Experimental results show a great performance when RIFD followed by huffman algorithm.

关键词： Compression ratio huffman algorithm lossy compression mobile applications

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Microscan Imager Logging Data Loss less Compression

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JOURNAL OF COMPUTATIONAL AND THEORETICAL NANOSCIENCE 2015年第7期12卷 1144-1149页

作者： Zhang, Yanhui Zhang, He Shi, Jun Yin, Xiaozheng Nanjing Univ Sci & Technol Sch Mech Engn Nanjing 210094 Jiangsu Peoples R China Henan Inst Engn Sch Mech Engn Zhengzhou 451191 Henan Peoples R China Zhengzhou Univ Light Ind Sch Elect Engn Zhengzhou 450002 Henan Peoples R China

The conflict between ever-increasing volumes of microscan imager logging data and limited cable transmission bandwidth intensifying day by day. In this paper, an improved lossless data compression algorithm is proposed. Specifically, according to the characteristics of the micro resistivity imaging logging data, it is proved that Hex character encoding has better compressibility than decimal character encoding. It analyzed that traditional quadtree huffman algorithm does not be fully applicable to microscan imager logging data. Lastly, it employed improved quadtree huffman algorithm for logging data compression so as to enhance the data compression ratio. The experiment comparsions show that, compared to the convention quadtree algorithm and the improved compressed huffman encoding, both elapsed time and compression ratio are a great improvement.

关键词： Microscan Imager Logging Logging Data Lossless Data Compression huffman algorithm

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A QUANTITATIVE ASSESMENT OF IMAGE COMPRESSION PARAMETERS AND ITS algorithm

A QUANTITATIVE ASSESMENT OF IMAGE COMPRESSION PARAMETERS AND...

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Global Conference on Communication Technologies (GCCT)

作者： Chithra, K. Perumal, B. Rajasekaran, M. Pallikonda Prasath, T. Arun Kalasalingam Univ Dept EEE Virudunagar Tamil Nadu India Kalasalingam Univ Dept ECE Virudunagar Tamil Nadu India

ISBN: (纸本)9781479985531

Image compression has an important role in the area of transmission and stores the lossless image compression. The aim of this project is to increase the image compression ratio and also the PSNR value, compress the large size of images in to small size. When the compression is high to compare the other algorithm of parameters it is a best of image compression algorithm. Thus the meaning of compression is to reduce the size of images. This small size of image files are used to store in the memory disk, and also used to reducing the transmitting time. To compare the parameters of compression algorithm is the SPIHT algorithm is the best algorithm of compression algorithm because it has a high compression ratio.

关键词： LZW algorithm SPIHT algorithm huffman algorithm

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Locality Aware Skip Graph 35

Locality Aware Skip Graph

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IEEE 35th International Conference on Distributed Computing Systems Workshops ICDCSW 2015

作者： Hassanzadeh-Nazarabadi, Yahya Kupcu, Alptekin Ozkasap, Oznur Koc Univ Dept Comp Engn Istanbul Turkey

ISBN: (纸本)9781467373036

Skip Graph, as a distributed hash table (DHT) based data structure, plays a key role in peer-to-peer (P2P) storage systems, distributed online social networks, search engines, and several DHT-based applications. In the Skip Graph structure, node identifiers define the connectivity. However, traditional identifier assignment algorithms do not consider the Skip Graph nodes' locations. Neglecting the nodes' localities in the identifier assignments results in high end-to-end latency in the overlay network which negatively affects the overall system performance. In this paper, we propose a method to assign the Skip Graph node identifiers considering their location information and make the nodes locality aware. In the proposed dynamic and fully decentralized algorithm, named DPAD, instead of assigning node identifiers uniformly at random, locality aware identifiers will be assigned to the nodes at their arrival to the system based on their distances to some super-nodes named landmarks. We define locality awareness as the similarity of the distances between the nodes in the overlay and underlay networks. Performance analysis results show that DPAD algorithm provides about 82% improvement in the locality awareness of node identifiers and about 40% improvement in the search query end-to-end latency, compared to the best known static and dynamic algorithms.

关键词： Skip graph P2P systems locality awareness end-to-end latency huffman algorithm

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Application of Improved Hybrid Compression algorithm in GPS Data Compression

Application of Improved Hybrid Compression Algorithm in GPS ...

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2015 4th International Conference on Mechatronics,Materials,Chemistry and Computer Engineering(ICMMCCE 2015)

作者： She Xuebing Zheng Xin Department of College of information engineering Jiangxi science and Technology InstituteNanchang 330098 China Department of College of information engineering Jiangxi science and Technology Institute

In the paper we introduce a hybrid compression algorithm, which is the co- mbination of huffman algorithm and RLE algorithm, for compressing the GPS data. This algorithm acquires statistical characteristics of GPS data according to the NMEA0183 protocol, mixes huffman algorithm and RLE algorithm to compress GPS data, to improve the coding efficiency and to restrain data expansion. huffman algori- thm has high compression rate on duplicated single-byte data while RLE algorithm has high compression rate on duplicated code segment. The flag bit is added in the process of encoding for encoding for the classification processing on GPS data in order to effectively identify the outputs of two kinds of algorithm when decoding and to ensure the complete decoding of compressed data. This improved hybrid compression algorithm is applied to local storage and 3G remote transmission of vehicle terminal GPS data, results show that the algorithm has clear improvement in compression performance of GPS data.

关键词： Hybrid compression algorithm huffman algorithm Run-Length Encoding(RLE) algorithm Vehicle monitor-ring system GSP data

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Medical Image Compression Using Ripplet Transform

Medical Image Compression Using Ripplet Transform

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International Conference on Intelligent Computing Applications (ICICA)

作者： Dhaarani, C. Venugopal, D. Raja, A. Sivanantha KLN Coll Informat Technol Dept ECE Madurai Tamil Nadu India AC Coll Engn & Technol Dept ECE Karaikkudi Tamil Nadu India

ISBN: (纸本)9781479939664

Now-a-days the medical image compression plays a major role in the image processing. Even though the technology is improvised but still it needs the storage space and efficient bandwidth utilization. This paper presents the compression of grey scale medical images. The proposed method uses a new transform called Ripplet Transform, a higher dimensional generalization of the curvelet transform used to represent the images or two dimensional signals at different scales and different directions and huffman algorithm to encode significant coefficients. The main goal of this method is to improve the compression ratio and to minimize the mean square error. From the experimental results obtained it is proved that the compression ratio and the peak to signal noise ratio is achieved high for various Medical images.

关键词： Medical image compression ripplet transform huffman algorithm compression ratio mean square error peak signal to noise ratio

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A criticism of the ACW algorithm

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COMPUTERS & MATHEMATICS WITH APPLICATIONS 2012年第8期64卷 2616-2620页

作者： Mohammadi, M. Saleh Naserasadi, Ali Shahid Bahonar Univ Zarnad Ind & Min Fac Comp Grp Kerman Iran Shahid Bahonar Univ Math & Comp Fac Dept Comp Kerman Iran

Data compression via the huffman algorithm, which is a data compression technique, is the most efficient technique between single symbol data compression techniques. This algorithm is counted among statistical data compression techniques. Many efforts have been made for optimizing this technique and some algorithms have been presented, too. One of these algorithms is the ACW algorithm which is presented by Hussein Al-Bahadili et al. At first, they used the huffman algorithm and then used the results of the huffman algorithm as the input of their algorithm to calculate the optimum character wordlength. So, they decreased the stored characters via increasing the character wordlength for doing the compression. In this paper, we examined and criticized the ACW algorithm and presented some of its weaknesses via suitable counterexamples. At the end, it was concluded that the optimum character wordlength can never be calculated by extant techniques. (C) 2012 Elsevier Ltd. All rights reserved.

关键词： Data compression huffman algorithm ACW algorithm

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Reverse-Engineering Scanning Keyboards

Reverse-Engineering Scanning Keyboards

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13th International Conference on Computers Helping People with Special Needs (ICCHP)

作者： Hamidi, Foad Baljko, Melanie York Univ Dept Comp Sci & Engn Toronto ON M3J 1P3 Canada

ISBN: (纸本)9783642315343

Scanning or soft keyboards are alternatives to physical computer keyboards that allow users with motor disabilities to compose text and control the computer using a small number of input actions. In this paper, we present the reverse huffman algorithm (RHA), a novel Information Theoretic method that extracts a representative latent probability distribution from a given scanning keyboard design. By calculating the Jensen-Shannon Divergence (JSD) between the extracted probability distribution and the probability distribution that represents the body of text that will be composed by the scanning keyboard, the efficiency of the design can be predicted and designs can be compared with each other. Thus, using RHS provides a novel a priori context-aware method for reverse-engineering scanning keyboards.

关键词： Scanning Keyboards Information Theory huffman algorithm

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