• Title, Summary, Keyword: 양자화 모델

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Macroblock Layer Bit-rates Control Algorithm based on the Linear Source Model (선형 모델 기반 매크로블록 레이어 비트율 제어 기법)

  • Seo Dong-Wan;Choe Yoonsik
    • Journal of the Institute of Electronics Engineers of Korea SP
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    • v.42 no.6
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    • pp.63-72
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    • 2005
  • In this paper, we propose the bit-rate control algorithm for the block based image compression like H.263, H.263+ or MPEG-4. The proposed algorithm is designed to identify the quantization parameter set through the Lagrangian optimization technique based on the well-known linear source model. We set the Lagrangian cost function with the rates and distortion calculated from the linear source model. We calculate the quantization parameter set using the Vitervi algorithm to solve the Lagrangian optimization problem considering the Dquant method of H.263 and MPEG-4. The proposed algorithm improves the video quality by up to 1.5 dB compared with the TMN8 scheme, and is more effective in the video sources with dynamic activities than the consistent quality approaches.

3-dimensional Mesh Model Coding Using Predictive Residual Vector Quantization (예측 잉여신호 벡터 양자화를 이용한 3차원 메시 모델 부호화)

  • 최진수;이명호;안치득
    • Journal of Broadcast Engineering
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    • v.2 no.2
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    • pp.136-145
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    • 1997
  • As a 3D mesh model consists of a lot of vertices and polygons and each vertex position is represented by three 32 bit floating-point numbers in a 3D coordinate, the amount of data needed for representing the model is very excessive. Thus, in order to store and/or transmit the 3D model efficiently, a 3D model compression is necessarily required. In this paper, a 3D model compression method using PRVQ (predictive residual vector quantization) is proposed. Its underlying idea is based on the characteristics such as high correlation between the neighboring vertex positions and the vectorial property inherent to a vertex position. Experimental results show that the proposed method obtains higher compression ratio than that of the existing methods and has the advantage of being capable of transmitting the vertex position data progressively.

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터널 전계 효과 트랜지스터의 양자모델에 따른 특성 변화

  • Lee, Ju Chan;Ahn, Tae Jun;Yu, Yun Seop
    • Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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    • pp.454-456
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    • 2017
  • Current and capacitance-voltage characteristics of tunnel field effect transistor (TFET) with various quantum models were investigated. Density gradient, Bohm quantum potential (BQP), and Vandort quantum correction are used with calibrating against Schrodinger-Poisson model. Drive-currents in all models. are decreased. When only BQP is used, SS and $V_{onset}$ are fixed but drive-current is decreased 3 times more than those of no quantum model. And When BQP with Vandort and density gradient are used, SS increased more than 40 mV./dec and $V_{onset}$ shifted as 0.07 eV.

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Adaptive Model-Based Quantization Parameter Decision for Video Rate Control (비디오 비트율 제어를 위한 적응적 모델 기반의 양자화 변수 결정 방법)

  • Kim, Seon-Ki;Ho, Yo-Sung
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.32 no.4C
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    • pp.411-417
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    • 2007
  • The rate control is an essential component in video coding to provide better quality under given coding constraints, such as channel capacity, frame rates, etc. In general, source data cannot be described as a single distribution in a video coding, hence it can cause an exhaustive approximation problem. It drops a coding efficiency under weak channel environments, such as mobile communications. In this paper, we design a new quantization parameter decision model that is based on a rate-distortion function of generalized Gaussian distribution. In order to adaptively express various source data distribution, we decide a shape parameter by observing a ratio of samples, which have a small value. For experiment, the proposed algorithm is implemented into H.264/AVC video codec, and its performance is compared with that of MPEG-2 TM5, H.263 TMN8 rate control algorithm. As shown in simulation results, the proposed algorithm provides an improved quality rather than previous algorithms and generates the number of bits closed to the target bits.

A JPEG Quantization Table Design for Mobile QVGA Images (모바일 QVGA 영상을 위한 JPEG 양자화 테이블 설계에 대한 연구)

  • Jeong, Gu-Min;Lee, Jong-Deok;Kang, Dong-Wook
    • The Journal of The Institute of Internet, Broadcasting and Communication
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    • v.8 no.1
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    • pp.19-24
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    • 2008
  • This paper presents a new JPEG quantization table design method for mobile images in handset. From the characteristics of the mobile images, we propose a modeling method of the quantization table and select the optimized pre-emphasis factor from various sets of $240{\times}320$ images. From the experiment, we show that the performance is improved in the sense of bpp and PSNR, applying the proposed method.

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Analysis of Phoneme/Isolated Word Recognition Rate Using Codebook and VQ Optimization (코드북과 VQ 최적화에 의한 음소/고립단어 인식률 분석)

  • Ahn, Hong-Jin;Joo, Sang-Hyun;Chin, Won;Kim, Ki-Doo
    • Proceedings of the IEEK Conference
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    • pp.675-678
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    • 1999
  • 본 논문에서는 음소별 코드북 개수의 선택과 벡터 양자화에 따른 음소 인식률과 고립단어 인식률에 대하여 다룬다. 음성모델은 이산 확률 밀도를 갖는 DHMM(Discrete Hidden Markov Model)을 사용하였으며, 코드북 생성과 벡터 양자화 알고리즘으로는 K-means 알고리즘과 LBG(Linde, Buzo, Gray) 알고리즘을 사용하였다 음소별 코드북 개수와 벡터 양자화를 최적화함으로써 음소 인식률을 향상시킬 수 있으며, 그 결과 안정된 고립단어 인식률을 얻을 수 있다.

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Coding Unit-level Multi-loop Encoding Method based on JND for Perceptual Coding (JND 모델을 사용한 코딩 유닛 레벨 멀티-루프 인코딩 기반의 비디오 압축 방법)

  • Lim, Woong;Sim, Donggyu
    • Journal of the Institute of Electronics and Information Engineers
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    • v.52 no.5
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    • pp.147-154
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    • 2015
  • In this paper, we employed a model which defines the sensitivity according to the background luminance, so called JND (Just Noticeable Difference), and applied to the video coding. The proposed method finds out the maximum possible quantization parameter for the current unit based on the threshold of JND model and reduce the bitrate with similar perceptual quality. It selects the higher quantization parameter and reduce the bitrate when the reconstructed signal which is coded with higher quantization parameter is in a range of allowance based on the JND threshold, i.e. the signal has the similar perceptual quality compared to that is coded with the initial quantization parameter. The proposed algorithm was implemented on HM16.0, which is a reference software of the latest video coding standard HEVC (High Efficiency Video Coding) and the coding performance was evaluated. Compared to HM16.0, the proposed algorithm achieved maximum 20.21% and 6.18% of average bitrate reduction with the similar perceptual quality.

An Adaptive Rate Control Using Piecewise Linear Approximation Model (부분 선형 근사 모델을 이용한 적응적 비트율 제어)

  • 조창형;정제창;최병욱
    • Journal of Broadcast Engineering
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    • v.2 no.2
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    • pp.194-205
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    • 1997
  • In video compression standards such as MPEG and H.263. rate control is one of the key components for good coding performance. This paper presents a simple adaptive rate control scheme using a piecewise linear approximation model. While conventional buffer control approach is performed by adjusting the quantization parameter linearly according to the buffer fullness. the proposed approach uses a piecewise linear approximation model derived from logarithmic relation between the quantization parameter and bitrate in data compression. In addition. a forward analyzer performed in the spatial domain is used to improve image quality. Simulation results demonstrate that the proposed method provides better performance than the conventional one and reduces the fluctuation of the PSNR per frame while maintaining the quality of the reconstructed frames at a relatively stable level.

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Quantized Channel State Information Feedback Scheme for Multi-carrier Systems (다중 반송파 시스템을 위한 양자화된 채널 상태 정보 피드백 기법)

  • Seo Hee-Jung;Kim Seayoung;Kim Nak-Myeong;Kim Kiho
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.30 no.12A
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    • pp.1146-1152
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    • 2005
  • In this paper, we propose a compressed quantized channel state information (CQCSI) feedback scheme for multi-carrier mobile communication systems. The proposed CQCSI figures out the contiguous subsequences of equal QCSI's as separate types of runs across the subcarriers, and then encodes the types of runs using a truncated Huffman coding algorithm. Computer simulation shows that the proposed algorithm can reduce the QCSI feedback up to one tenth of the uncompressed, while providing a comparable performance with the conventional QCSI feedback schemes. To cope with special cases when the frequency selective fading is very high, we also propose a restricted CQCSI feedback scheme. The restricted CQCSI feedback has been proved under vehicular B channel model.

A Rate Control Algorithm for the H.264 Video Coding Standard (H.264 비디오 부호화 표준을 위한 비트율 제어 알고리즘)

  • Kim Seon-Ki;Ho Yo-Sung
    • Proceedings of the Korean Society of Broadcast Engineers Conference
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    • pp.11-15
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    • 2003
  • 비디오 부호화기에서는 채널의 용량과 같은 주어진 제약 조건을 만족하면서 좋은 화질을 얻기 위해 비디오 부호화 시 적절한 양자화 변수를 결정해야 한다. 본 논문에서는 H.264 비디오 부호화 표준에서 높은 압축 효율을 철기 위해 비트 율 왜곡 모델에 기반 한 새로운 비트 율 제어 알고리즘을 제안한다. 특히. 부호화된 매크로블록의 특성과 이전에 부호화 된 매크로 발생 비트수를 고려하여. 제안한 비트 율 모델을 통해 양자화 변수 값을 결정한다. 본 논문에서 제안한 알고리즘은 목표 비트수에 가깝고. 기존치 방법보다 개선된 화질을 제공한다.

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