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[Keyword] adaptive quantization(5hit)

1-5hit
  • Improved Block Truncation Coding Using Multimode Color Conversion to Reduce Frame Memory in LCD Overdrive

    Moonki CHO  Yungsup YOON  

     
    PAPER-Digital Signal Processing

      Vol:
    E100-A No:1
      Page(s):
    251-258

    The overdrive technique is widely used to eliminate motion blur in liquid-crystal displays (LCDs). However, this technique requires a large frame memory to store the previous frame. A reduction in the frame memory requires an image compression algorithm suitable for real-time data processing. In this paper, we present an algorithm based on multimode-color-conversion block truncation coding (MCC-BTC) to obtain a constant output bit rate and high overdrive performance. The MCC-BTC algorithm uses four compression methods, one of which is selected. The four compression modes either use the single-bitmap-generation method or the subsampling method for chrominance. As shown in the simulation results, the proposed algorithm improves the performance of both coding (up to 2.73dB) and overdrive (up to 2.61dB), and the visual quality is improved in comparison to other competing algorithms in literature.

  • A Perceptually Adaptive QIM Scheme for Efficient Watermark Synchronization

    Hwai-Tsu HU  Chu YU  

     
    LETTER-Information Network

      Vol:
    E95-D No:12
      Page(s):
    3097-3100

    This study presents an adaptive quantization index modulation scheme applicable on a small audio segment, which in turn allows the watermarking technique to withstand time-shifting and cropping attacks. The exploitation of auditory masking further ensures the robustness and imperceptibility of the embedded watermark. Experimental results confirmed the efficacy of this scheme against common signal processing attacks.

  • Per-User Automatic Gain Control for an Uplink CDMA Receiver

    Jungwoo LEE  

     
    LETTER-Spread Spectrum Technologies and Applications

      Vol:
    E89-A No:4
      Page(s):
    1154-1157

    A per-user AGC technique is proposed to combat the signal level variation of an individual user in a DS-CDMA receiver. A simple signal model for a Rake receiver is derived, and the potential cause of the signal variation in the Rake receiver output is discussed. The adaptive scheme is also compared with a conventional fixed quantization scheme in simulations.

  • A Bit-Operation Algorithm of the Median-Cut Quantization and Its Hardware Architecture

    Shogo MURAMATSU  Hitoshi KIYA  Akihiko YAMADA  

     
    PAPER

      Vol:
    E83-A No:2
      Page(s):
    320-328

    In this paper, an algorithm of the median-cut quantization (MCQ) is proposed. MCQ is the technique that reduces multi-valued samples to binary-valued ones by adaptively taking the median value as the threshold. In this work, the search process of the median value is derived from the quick-sort algorithm. The proposed algorithm searches the median value bit by bit, and samples are quantized during the search process. Firstly, the bit-serial procedure is shown, and then it is modified to the bit-parallel procedure. The extension to the multi-level quantization is also discussed. Since the proposed algorithm is based on bit operations, it is suitable for hardware implementation. Thus, its hardware architecture is also proposed. To verify the significance, for the application to the motion estimation, the performance is estimated from the synthesis result of the VHDL model.

  • Digital Watermarking Technique for Motion Pictures Based on Quantization

    Hiroshi OGAWA  Takao NAKAMURA  Atsuki TOMIOKA  Youichi TAKASHIMA  

     
    PAPER

      Vol:
    E83-A No:1
      Page(s):
    77-89

    A quantization-based watermarking system for motion pictures is proposed. In particular, methods for improving the image quality of watermarked video, the watermarking data tolerance, and the accuracy of watermark data detection are described. A quantitative evaluation of the reliability of watermarked data, which has not generally been discussed up to now, is also performed.