Real-coded adaptive range genetic algorithm (ARGA) has been applied to a practical three-dimensional shape optimization for aerodynamic design of an aircraft wing. The real-coded ARGA possesses both advantages of the ...
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Human face images form the important database in banks, security kiosks, police departments and they are also found in abundance in day-to-day life. In these databases the important content, of course is the face regi...
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ISBN:
(纸本)0819437034
Human face images form the important database in banks, security kiosks, police departments and they are also found in abundance in day-to-day life. In these databases the important content, of course is the face region. In this paper, we present two highly efficient methods for compressing face images. The first method, which is lossy, detects the human faces in the wavelet domain for discriminative quantization to achieve high perceptual quality content-based image compression. This method gives superior subjective performance over JPEG standard without sacrificing the performance in the rate-distortion spectrum. The second method, which is lossy as well as lossless, also detects the human faces in the wavelet domain so that lossy/lossless mode can be selected dynamically for compression. This method gives the best solution to applications which can not tolerate losses for face regions. The method improves the overall coding efficiency by adapting lossy mode for non-face regions instead of coding entire image in lossless mode.
In 1994 Peter Fenwick at the University of Auckland devised an elegant mechanism for tracking the cumulative symbol frequency counts that are required for adaptive arithmetic coding. His structure spends O(log n) time...
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In 1994 Peter Fenwick at the University of Auckland devised an elegant mechanism for tracking the cumulative symbol frequency counts that are required for adaptive arithmetic coding. His structure spends O(log n) time per update when processing the sth symbol in an alphabet of n symbols. In this note we propose a small but significant alteration to this mechanism, and reduce the running time to O O(log (1 + s)) time per update. If a probability-sorted alphabet is maintained, so that symbol s in the alphabet is the sth most frequent, the cost of processing each symbol is then linear in the number of bits produced by the arithmetic coder. Copyright (C) 1999 John Wiley & Sons, Ltd.
This paper presents the Swiss Federal Institute of Technology (EPFL) proposal to MPEG-4 video coding standardization activity [1]. The proposed technique is based on a novel approach to audio-visual data compression e...
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This paper presents the Swiss Federal Institute of Technology (EPFL) proposal to MPEG-4 video coding standardization activity [1]. The proposed technique is based on a novel approach to audio-visual data compression entitled dynamic coding, The newly born multimedia environment supports a plethora of applications which cannot be covered adequately by a single compression technique. dynamic coding offers the opportunity to combine several compression techniques and segmentation strategies. Given a particular application, these two degrees of freedom can be constrained and assembled in order to produce a particular profile which meets the set of specifications dictated by the application. The basic principles of this approach are presented together with the data representation system. The major characteristics of dynamic coding are reviewed, along with simulation results showing the performance of such an approach in a very low bit-rate video coding environment.
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