P. Czerepinski

University of Bristol, Bristol, ENG, United Kingdom

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Publications (5)8.29 Total impact

  • Source
    Przemyslaw Czerepinski · Colin Davies · Nishan Canagarajah · David Bull
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    ABSTRACT: Matching pursuits over a basis of separable Gabor functions has been demonstrated to outperform DCT methods for displaced frame difference coding for video compression. Unfortunately, apart from very low bit-rate applications, the algorithm involves an extremely high computational load. This paper contains an original contribution to the issues of dictionary selection and fast implementation for matching pursuits video coding. First, it is shown that the PSNR performance of existing matching pursuits codecs can be improved and the implementation cost reduced by a better selection of dictionary functions. Secondly, dictionary factorization is put forward to further reduce implementation costs. A reduction of the computational load by a factor of 20 is achieved compared to implementations reported to date. For a majority of test conditions, this reduction is supplemented by an improvement in reconstruction quality. Finally, a pruned full-search algorithm is introduced, which offers significant quality gains compared to the better-known heuristic fast-search algorithm, while keeping the computational cost low
    Preview · Article · Nov 2000 · IEEE Transactions on Circuits and Systems for Video Technology
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    ABSTRACT: This paper introduces an error resilient implementation of the matching pursuits algorithm for video coding. The video bitstream is transmitted using a simulation of the Bluetooth air interface standard, which recommends ARQ as a means of overcoming channel errors in the data packets. This approach may be unsuitable for real time and broadcast applications. Therefore, a modified receiver is proposed in this paper, which does not request the retransmission of erroneous packets, but instead passes them to the video decoder to exploit error resilience. This strategy is shown to be superior to a standard compliant system if ARQ cannot be applied. The work confirms that wireless communication standards should support a transparent mode for video applications
    Preview · Article · Sep 2000 · IEEE Transactions on Consumer Electronics
  • P. Czerepinski · M.F. Tariq · D. Bull · N. Canagarajah · A. Nix
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    ABSTRACT: Matching pursuits over a basis of separable Gabor functions has been demonstrated to outperform DCT methods for low bit rate video coding. This paper introduces an error resilient implementation of the matching pursuits algorithm, based on the error resilient positional code. Coded video is transmitted using the simulated HIPERLAN/1 air interface standard, which recommends ARQ as a means of overcoming channel errors. This may be unsuitable for real time and broadcast applications. Therefore, a modified HIPERLAN/1 receiver is proposed in this paper, which does not use ARQ to retransmit erroneous packets but instead passes them to the video decoder to exploit error resilience. This strategy provides an acceptable reconstruction quality for average bit error rates equal to 1 in 1000 and is superior to a standard compliant system in the absence of ARQ. This confirms that wireless LAN standards should support a transparent mode for video applications
    No preview · Conference Paper · Feb 2000
  • Przemyslaw Czerepinski · Colin Davies · Cedric Nishan Canagarajah · David R. Bull

    No preview · Article · Jan 2000
  • Source
    David Bull · Nishan Canagarajah · Przemyslaw Czerepinski
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    ABSTRACT: Matching pursuits is a dictionary-based coding method, which has recently been demonstrated to outperform standard techniques, such as H.263, at low bit rate video compression. Unfortunately, the method involves an extremely high computational cost, compared to the DCT-based H.263. The contribution of this paper relies on reporting three new dictionaries for matching pursuits video coding, whose advantages include both a reduced computational cost and improved PSNR performance, compared to dictionaries reported to date
    Preview · Conference Paper · Aug 1999