Browsing by Subject "Data compression (Computer science)"
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Item Content-based compression of mammograms with JPEG2000(Texas Tech University, 2003-05) Chan, Hung YamThis thesis presents three strategies for the content-based compression (CBC) of mammograms. The first strategy is based on a previous CBC approach [1], while the last two strategies utilizing a modified version of the JPEG2000 standard. Unlike the traditional compression techniques, CBC is comprised of segmentation and compression processes. In this two-step process, the clinically important structures are first identified via a fractal-based segmentation method. Then, a compression strategy is applied in such a way that the extracted structures from the first step are compressed losslessly while the remaining regions are lossily compressed. The first two strategies introduced in this thesis achieve lossless and lossy compression with separate compression engines. On the other hand, the last strategy achieves CBC with a single IPEG2000 compression engine using the max-shift ROI (Regions-of-Interest) coding method. Preliminary results show that the fractal-based segmentation method covers, on average, over 90% of calcifications. For mammograms with masses, subjective observation shows that over 80% of images will have at least the mass boundaries covered. Also, the two newly proposed CBC strategies can achieve an average compression ratio of 14:1 with PSNR of more than 41dB, while completely preserving the clinically important regions for digitized mammograms. For digital mammograms, the achievable compression ratio is even higher (-20:1) with PSNR greater than 50 dB.Item Data compression application to the MIL-STD 1553 avionics data bus.(2006-05-11T16:11:15Z) Weston, Bron O.; Duren, Russell Walker.; Thompson, Michael Wayne.; Engineering.; Baylor University. Dept. of Electrical and Computer Engineering.With the current state of legacy military avionic systems reaching its ceiling in memory space, processing power, and data-bus through-put (bandwidth), a need has arisen to maximize its limited resources to avoid extensive costs of system overhaul. Specifically, F/A-18 C/D Aircraft is approaching message capacity on its MIL-STD-1553 buses. To slow this assent to capacity limits, one possible solution implements data compression techniques to increase bandwidth. In these efforts, this thesis examines different lossless compression schemes to find ideal options to consider for implementation on MIL-STD-1553 based F/A-18 C/D Aircraft. Several compression routines are identified that provide significant data compression while requiring very little computational effort. A surprising benefit is that the reduction in wasted time spent waiting on data communication more than offsets the time required to compress and decompress the data.Item Data reduction algorithms for distributed query processing(Texas Tech University, 1984-08) Wang, Jia-shinnNot availableItem Impact of the LZW-based common subexpression elimination algorithm on SAT-solving efficiency(2012-05) Jn Charles, Jeriah; Zhang, Yuanlin; Gelfond, Michael; Watson, RichardThe Satisfiability (SAT) problem is the problem of finding an assignment that satisfies a given propositional formula. SAT is effective in solving many important problems in areas such as automated reasoning, computer-aided design, and planning in Artificial Intelligence. The need to solve these problems in a reduced amount of time has geared considerable research in improving the performance of SAT solvers resulting in many solver algorithms being created or modified. This research investigates how the removal of common subexpressions in a formula via the Lempel–Ziv-Welch (LZW)-based approach can affect the efficiency of SAT solving. By substituting common subexpressions for new variables in the original formula, we compare the results of passing the original formula and the new equivalent formula through a SAT solver. In this LZW-based approach, we modify the Lempel–Ziv-Welch data compression algorithm to find and substitute the common subexpressions in the formula.Item Implementation of lossless compression algorithms for the MIL-STD-1553.(2009-04-01T19:25:47Z) Lam, Bernard O.; Thompson, Michael Wayne.; Duren, Russell Walker.; Engineering.; Baylor University. Dept. of Electrical and Computer Engineering.This thesis focuses on the bandwidth limitations faced by the legacy MIL-STD-1553 data bus. In order to improve bandwidth performance, lossless implementations of data compression routines have been proposed. Using data bus captures from the F/A-18 C/D simulator it has been possible to determine data characteristics, resulting in statistics showing the inherent redundancies within the data. This thesis proposes three compression algorithms which have been developed for use on the MIL-STD-1553 data bus. The three methods are Common Value Tracking, Modified Run-Length Encoding, and Differential Encoding. It will be shown that in some cases, compression ratios over 10 to 1 are possible, significantly improving the data transfer capabilities of the legacy communication system. The compression algorithms have been designed to provide bounded deterministic operation as required by real-time systems. In this thesis we will explore the strengths and weakness of each of these algorithms and also the decisions and challenges associated with integration with MIL-STD-1553 systems.Item New test vector compression techniques based on linear expansion(2004) Chakravadhanula, Krishna V.; Touba, Nur A.