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Showing papers on "Run-length encoding published in 2007"


Proceedings ArticleDOI
09 Nov 2007
TL;DR: RLH was implemented and experimentally compared to the well known Word Aligned Hybrid bitmap compression technique and it is shown that RLH offers shorter query response times than WAH, for certain cardinalities of indexed attributes.
Abstract: In this paper we present a technique of compressing bitmap indexes for application in data warehouses. The developed compression technique, called Run-Length Huffman (RLH), is based on the run-length encoding and on the Huffman encoding. RLH was implemented and experimentally compared to the well known Word Aligned Hybrid bitmap compression technique that has been reported to provide the shortest query execution time. The experiments discussed in this paper show that RLH offers shorter query response times than WAH, for certain cardinalities of indexed attributes. Moreover, bitmaps compressed with RLH are smaller than corresponding bitmaps compressed with WAH. Additionally, we propose a modified RLH, called RLH-1024, which is designed to better support bitmap updates.

29 citations


Patent
21 Aug 2007
TL;DR: In this paper, a look-up table is used to map the scan order of quantization to the zig-zag order of run length encoding, and variable length coding and inverse quantization optionally take place within the run length decoding loop.
Abstract: A computer implemented method of video date encoding generates a mask having one bit corresponding each spatial frequency coefficient of a block during quantization. The bit state of the mask depends upon whether the corresponding quantized spatial frequency coefficient is zero or non-zero. The runs of zero quantized spatial frequency coefficients determined by a left most bit detect instruction are determined from the mask and run length encoded. The mask is generated using a look up table to map the scan order of quantization to the zig-zag order of run length encoding. Variable length coding and inverse quantization optionally take place within the run length encoding loop.

29 citations


Journal ArticleDOI
TL;DR: In this paper, a real-time image processing algorithm based on run length encoding (RLE) for a vision-based intelligent controller of a humanoid robot system is presented.
Abstract: This paper introduces a real-time image processing algorithm based on run length encoding (RLE) for a vision-based intelligent controller of a Humanoid Robot system. The RLE algorithms identify objects in the image, providing their size and position. The RLE Hough transform is also presented for recognition of landmarks in the image to aid robot localization. The vision system presented has been tested by simulating the dynamics of the robot system as well as the image processing subsystem

29 citations


Book ChapterDOI
09 Jul 2007
TL;DR: This work presents a method to speed up the dynamic program algorithms used for solving the HMM decoding and training problems for discrete time-independent HMMs and describes three algorithms based alternatively on byte pair encoding, run length encoding and Lempel-Ziv parsing.
Abstract: We present a method to speed up the dynamic program algorithms used for solving the HMM decoding and training problems for discrete time-independent HMMs. We discuss the application of our method to Viterbi's decoding and training algorithms [21], as well as to the forward-backward and Baum-Welch [4] algorithms. Our approach is based on identifying repeated substrings in the observed input sequence. We describe three algorithms based alternatively on byte pair encoding (BPE) [19], run length encoding (RLE) and Lempel-Ziv (LZ78) parsing [22]. Compared to Viterbi's algorithm, we achieve a speedup of Ω(r) using BPE, a speedup of Ω(r/log r ) using RLE, and a speedup of Ω(log n/k) using LZ78, where k is the number of hidden states, n is the length of the observed sequence and r is its compression ratio (under each compression scheme). Our experimental results demonstrate that our new algorithms are indeed faster in practice. Furthermore, unlike Viterbi's algorithm, our algorithms are highly parallelizable.

28 citations


Book ChapterDOI
09 Jul 2007
TL;DR: This paper analyzes Move-to-Front, Distance Coding and Inversion Frequencies from the point of view of how effective they are in the task of compressing low-entropy strings, that is, strings which have many regularities and are therefore highly compressible.
Abstract: Move-to-Front, Distance Coding and Inversion Frequencies are three somewhat related techniques used to process the output of the Burrows-Wheeler Transform. In this paper we analyze these techniques from the point of view of how effective they are in the task of compressing low-entropy strings, that is, strings which have many regularities and are therefore highly compressible. This is a non-trivial task since many compressors have non-constant overheads that become non-negligible when the input string is highly compressible. Because of the properties of the Burrows-Wheeler transform, being locally optimal ensures an algorithm compresses low-entropy strings effectively. Informally, local optimality implies that an algorithm is able to effectively compress an arbitrary partition of the input string. We show that in their original formulation neither Move-to-Front, nor Distance Coding, nor Inversion Frequencies is locally optimal. Then, we describe simple variants of the above algorithms which are locally optimal. To achieve local optimality with Move-to-Front it suffices to combine it with Run Length Encoding. To achieve local optimality with Distance Coding and Inversion Frequencies we use a novel "escape and re-enter" strategy. Since we build on previous results, our analyses are simple and shed new light on the inner workings of the three techniques considered in this paper.

23 citations


Proceedings ArticleDOI
07 Mar 2007
TL;DR: Modified runlength JPEG (MR-JPEG), which uses separate coding of three symbols (RUNLENGTH, SIZE, AMPLITUDE) to code the information, demonstrates higher compression with better quality.
Abstract: A number of image compression systems have been developed to save storage space and transmission bandwidth. The field of image compression has witnessed a lot of research on improving JPEG or evolving a codec with better performance. In the JPEG standard, run length encoding is used to code the string of zeros resulting from crude quantization of AC coefficients. In this paper we propose modified runlength JPEG (MR-JPEG), which uses separate coding of three symbols (RUNLENGTH, SIZE, AMPLITUDE) to code the information. To compare the results with the earlier scheme, we use two parameters-maximum difference (MD) for perceptual quality measurement and size (in KB's) for compression. Our results show that for large size images (512times512 and above), proposed scheme demonstrates higher compression with better quality.

10 citations


Proceedings ArticleDOI
12 Nov 2007
TL;DR: The application of the algorithm to a wide range of standard images shows that the scheme, while having low computational complexity, is competitive with other near-lossless image compression methods.
Abstract: In this paper an algorithm is proposed which performs near-lossless image compression. For each pixel in a row of the image a group of value-states are considered, which have values close to that of the pixel. A trellis is constructed for every row of the image where the nodes of the trellis are the states of the pixels of that row. The goal of the algorithm is to find a path on this trellis that creates a sequence which can be efficiently coded using run length encoding (RLE). For sections of the pixels of the row that suitable RLE cannot be achieved then minimization of the entropy is employed to complete a path on the trellis. The application of the algorithm to a wide range of standard images shows that the scheme, while having low computational complexity, is competitive with other near-lossless image compression methods.

9 citations


Book ChapterDOI
31 May 2007
TL;DR: The experimental results demonstrated that the RLM has advantages with respect to different types of data and run length encoding value match.
Abstract: This study proposes a data hiding method based on run length encoding. This proposed method uses the location of accumulated run length values, where the cover data run length are compared with the secret data run length. The run length matching (RLM) method uses the run length table which is constructed from the cover and secret data. The experimental results demonstrated that the RLM has advantages with respect to different types of data and run length encoding value match.

7 citations


Patent
Lippincott Louis1
20 Sep 2007
TL;DR: In this article, a method of selectively run length encoding data may include removing a trigger value from one or more data elements if the trigger value is present in the data elements and calculating a run length of the one ormore data elements.
Abstract: A method of selectively run length encoding data may include removing a trigger value from one or more data elements if the trigger value is present in the one or more data elements and calculating a run length of the one or more data elements. The method may also include encoding the one or more data elements as a command pair when the run length is greater than two. The command pair may include the trigger value. The one or more data elements may be output without encoding the one or more data elements when the run length is not greater than two.

6 citations


Journal ArticleDOI
TL;DR: The experimental results show that the TRLE data compression scheme with the rotate-tiling data communication scheme outperforms other eleven image composition methods for all test samples.
Abstract: Data compression is a well-known method to improve the image composition time of parallel volume rendering on distributed memory multicomputers. In this paper, we propose an efficient data compression scheme, the template run-length encoding (TRLE) scheme, for image composition. Given an image with 2n×2n pixels, in the TRLE scheme, the image is treated as n×n blocks and each block has 2×2 pixels. Since a pixel can be a blank or non-blank pixel, there 16 templates in a block. To compress an image, the TRLE scheme encodes an image block by block similar to the run-length encoding scheme. However, the TRLE scheme can filter out or use small space to encode blocks whose four pixels are blank pixels, that is, the TRLE scheme can encode a partial image according to the shape of non-blank pixels. To evaluate the performance of the TRLE scheme, we compare the proposed scheme with the BR, the RLE, and the BRLC schemes. Since a data compression scheme needs to cooperate with some data communication schemes, in the implementation, the binary-swap, the parallel-pipelined, and the rotate-tiling data communication schemes are used. By combining the four data compression schemes with the three data communication schemes, we have twelve image composition methods. These twelve methods are implemented on an IBM SP2 parallel machine. Four volume datasets are used as test samples. The data computation time and the data communication time are measured. The experimental results show that the TRLE data compression scheme with the rotate-tiling data communication scheme outperforms other eleven image composition methods for all test samples.

5 citations


Patent
20 Sep 2007
TL;DR: A method of selectively run length encoding data may include removing a trigger value from one or more data elements if the trigger value is present in the one orMore data elements and calculating a run length of the one-time-use data elements.
Abstract: A method of selectively run length encoding data may include removing a trigger value from one or more data elements if the trigger value is present in the one or more data elements and calculating a run length of the one or more data elements. The method may also include encoding the one or more data elements as a command pair when the run length is greater than two. The command pair may include the trigger value. The one or more data elements may be output without encoding the one or more data elements when the run length is not greater than two.

Journal Article
TL;DR: Experimental results show that the modified adaptive run length encoding algorithm can efficiently reduce the length of code when the series code streams have the same length.
Abstract: A modified adaptive run length encoding algorithm was proposed based on a wavelet transform with mathematical morphology.By utilizing morphological dilation,a mass of long series "0" code stream appearing in the bit-plane,adaptive run length encoding algorithm can encode images efficiently.The codeword of the optimal RLC should be equal to the actual length of run length that is corresponding to the total bits of binary code.A salient new feature of the modified adaptive run length encoding algorithm is that the original bit-steam is transformed into the original code length binary encode.Experimental results show that the modified algorithm can efficiently reduce the length of code when the series code streams have the same length.

Proceedings ArticleDOI
26 Sep 2007
TL;DR: The simulation experiment indicates that this algorithm can receive good compression performance of average CR≥ 7 and average PSNR ≥ 33dB for RSMI of different content and texture and requires small storage and is easy to be realized in hardware, so it is suitable for space-borne application.
Abstract: According to the correlated characteristic of remotely sensed multispectral images (RSMI) in the spectral and spatial domains, an effective and lossy YCrCb+IWT compression algorithm is proposed. The algorithm combines YCrCb transform with integer wavelet transform (IWT) to compress data, and data redundance of spectral and spatial domains is removed respectively. The important degree of the each subband is determined according to the energy of the each subband. Furthermore, each subband is quantified using adaptive threshold according to their important degree, then fixed bit-plane coding and Run Length Encoding are individually used to the quantified data of every subband and important graph. When implementing compression algorithm, in order to ensure better quality of reconstructed image, the compression with little distortion is utilized for luminance information Y. Simultaneously, in order to obtain higher compression ratio, the compression with biggish distortion is carried out for chrominance information Cr and Cb. The simulation experiment indicates that this algorithm can receive good compression performance of average CR≥ 7 and average PSNR ≥ 33dB for RSMI of different content and texture. In addition, the algorithm requires small storage and is easy to be realized in hardware, so it is suitable for space-borne application.

Journal Article
TL;DR: It has been proved that the algorithm presented in this paper is much more effective in the compression effect than the traditional RLE algorithm.
Abstract: This paper brings forwards an improved compression algorithm of RLE based on analyzing the disadvantages of the RLE.At the beginning,the algorithm sets an initial threshold and writes down the maximum and minimum value during the process of scanning.When the difference value between the maximum value and minimum value exceeds the threshold,it enlarges the threshold properly as long as the threshold is less than the restricted value,then divided the dataflow into several segmentations and adopt the differential-coding or natural -coding defined in this paper according to the real situation.In the process of coding,the minimum value,start position,the end position,coding number of bits,and the document including the difference value between the original value and the minimum value are used in order to be reverted to the original data.The compression formula is given through testing and comparing of the instance.It has been proved that the algorithm presented in this paper is much more effective in the compression effect than the traditional RLE algorithm.

Proceedings Article
01 Jan 2007
TL;DR: The algorithm discussed in this paper not only compresses the DNA sequence, but also allows one to generate finite length sequences, which can be used to find approximate pattern matches.
Abstract: Rapid advancements in research in the field of DNA sequence discovery has led to a vast range of compression algorithms. The number of bits required for storing four bases of any DNA sequence is two, but efficient algorithms have pushed this limit lower. With the constant decrease in prices of memory and communication channel bandwidth, one often doubts the need of such compression algorithms. The algorithm discussed in this paper hence not only compresses the DNA sequence, but also allows one to generate finite length sequences, which can be used to find approximate pattern matches. DNA sequences are mainly of two types, Repetitive and Non-Repetitive. The compression technique used is meant for the non-repetitive parts of the sequence, where we make use of the fact that a DNA sequence consists of only 4 characters. The algorithm achieves bit/base ratio of 1.3 - 1.4(dependant on the database), but more importantly one of the stages of the algorithm can be used for efficient discovery of approximate patterns. Copyright © 2007 IICAI.

Journal Article
TL;DR: In this paper, an adaptive method of compression of still images is presented, which consists first on a semi-automatic extraction of the region of interest (ROI), and the background (BG) and the ROI are then processed separately so as to preserve the information in the ROIs and degrade in a controlled way the BG.
Abstract: In most image processing applications, the user is only interested in part of the information conveyed through the image. In this paper, we present an adaptive method of compression of still images. It consists first on a semi-automatic extraction of the region of interest (ROI). The background (BG) and the ROI are then processed separately so as to preserve the information in the ROI and degrade in a controlled way the BG. using reversible and irreversible techniques such as JPEG, JPEG 2000 and Run Length Encoding (RLE). Performances of these techniques in terms of compression rate are compared based on their applications to biomedical and satellite images.