• Title, Summary, Keyword: 양자화 모델

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Just noticeable quantization blur model based on the DCT complexity feature of the image (영상의 복잡도 특징을 기준으로 양자화 왜곡에 대한 최소 인지 왜곡 모델)

  • Ki, Sehwan;Kim, Munchurl
    • Proceedings of the Korean Society of Broadcast Engineers Conference
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    • pp.70-72
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    • 2016
  • 본 논문에서는 기존의 인지적 영상 압축 기법에 사용되었던 Just Noticeable Distortion(JND) 모델이 압축과정에서 생기는 왜곡인 양자화 왜곡에 적합하지 않는 다는 것을 보이고, 그 한계점을 해결하기 위하여 Just Noticeable Blur(JNB)의 개념을 적용하여 영상 압축에 적합한 모델을 제시하였다. 주파수 공간에서 영상의 복잡도 특징을 나타내는 Spectral Contras Index(SCI) 값을 사용해서 영상의 DCT 블록별 JNB 를 추정하고 이를 기반으로 영상의 DCT 계수 값을 감소시켜 최신의 DCT 기반 JND 를 적용한 인지적 압축 영상에 비해 더 낮은 PSNR 을 가지면서 왜곡도 인지되지 않는 영상을 얻을 수 있었다. 새롭게 제시한 모델을 적용하면 인지적 영상압축에서 기존의 방법보다 더 낮은 비트율로 유사한 인지적 화질 성능을 발휘할 것으로 예상된다.

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Model Parameter-based Rate Control Algorithm for Constant Quality Real-Time Video Coding (실시간 부호화를 위한 모델 파라미터 기반 일정 화질 비트율 제어 기법)

  • Jeong, Jin-Woo;Cho, Kyung-Min;Choe, Yoon-Sik
    • Journal of the Institute of Electronics Engineers of Korea SP
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    • v.45 no.3
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    • pp.93-102
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    • 2008
  • In this paper, we propose a rate control algorithm for constant quality real time video coding. To achieve constant quality, previous algorithm exploit mean absolute of difference(MAD) as measure of frame complexity. However, if scene is abruptly changed or if quantization parameter is not constant, encoder produces various output bits with same MAD. Therefore we know that MAD does not appropriately reflect characteristic of frame. To solve this problem, we exploit model parameter as measure of frame complexity. Because model parameter means slope between output bits and MAD, it reflects correctly complexity of frame. And because previous model, R-MAD model, is not considered quantization parameter, as quantization parameter increases or decreases, model parameter of frame also vary. So model parameter obtained using previous model cannot reflect internal characteristic of video. We solve this problem using proposed model, which is considered quantization parameter. Experiment results show that our algorithm provide better performance, in terms of quality smoothness than previous algorithm. Especially, when scene is abruptly changed, our algorithm alleviates quality drop.

An Extended Color Histogram Intersection for Matching Adaptively Quantized Color Distribution (상이한 칼라로 구성된 영상의 정합을 위한 확장 칼라 히스토그램 인터섹션 방법)

  • 박소연;김성영;김민환
    • Proceedings of the Korea Multimedia Society Conference
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    • pp.415-418
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    • 2003
  • 칼라 히스토그램 인터섹션 방법은 칼라 분포간의 유사도를 측정하는데 널리 사용된다 하지만 이 방법은 칼라 공간을 고정된 칼라수로 양자화시킨 경우에만 유효하므로 칼라 공간에 대한 분할 문제와 양자화 레벨의 결정 문제를 내포하고 있다. 이에, 본 논문에서는 고정 양자화된 칼라 분포뿐만 아니라 적응적 양자화되어 상이한 칼라분포를 갖는 영상간의 정합에 적용 가능한 확장 칼라 히스토그램 인터섹션 방법을 제안한다. 제안된 방법은 생산자가 생산된 상품을 소비자에게 공급하는 동안 생산효율을 계산하여 경제적 이익을 최대화 시키기 위한 생산자-소비자 모델로 간주되어질 수 있다 실험을 통해 우리는 제안된 방법이 두 칼라 분포간의 유사도를 효과적으로 측정할 수 있음을 확인하였다

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Vector Quantization based Speech Recognition Performance Improvement using Maximum Log Likelihood in Gaussian Distribution (가우시안 분포에서 Maximum Log Likelihood를 이용한 벡터 양자화 기반 음성 인식 성능 향상)

  • Chung, Kyungyong;Oh, SangYeob
    • Journal of Digital Convergence
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    • v.16 no.11
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    • pp.335-340
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    • 2018
  • Commercialized speech recognition systems that have an accuracy recognition rates are used a learning model from a type of speaker dependent isolated data. However, it has a problem that shows a decrease in the speech recognition performance according to the quantity of data in noise environments. In this paper, we proposed the vector quantization based speech recognition performance improvement using maximum log likelihood in Gaussian distribution. The proposed method is the best learning model configuration method for increasing the accuracy of speech recognition for similar speech using the vector quantization and Maximum Log Likelihood with speech characteristic extraction method. It is used a method of extracting a speech feature based on the hidden markov model. It can improve the accuracy of inaccurate speech model for speech models been produced at the existing system with the use of the proposed system may constitute a robust model for speech recognition. The proposed method shows the improved recognition accuracy in a speech recognition system.

A Simple Transcoding Method for H.264 Coding System (H.264 부호화시스템에서 간단한 비트열 변환 기법)

  • Yang, Young-Hyun;Kwon, Soon-Kak
    • Journal of Korea Multimedia Society
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    • v.9 no.7
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    • pp.818-826
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    • 2006
  • In this paper, we investigate the relationship of bitrate and quantization parameter needed for the trans-coding method that makes the H.264 bitstream of a particular bitrate to the other titrate. Also we propose the new method in order to transcode the titrate between H.264 video coded bitstreams. The proposed transcoding method updates the model parameters from previous picture or slice by using the approximated relationship of bitrate and quantization step-size and finds the target quantization step-size, and then generates the target titrate by simple coding processing just after requantization. Therefore, the proposed method does not need the complex bitrate control and converts to the target titrate by simple implementation. From simulation, we can see that the proposed method transcodes exactly to an assigned target bitrate for the four test sequences with different their characteristics.

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Spectral recovery method based on TCX mode using CNN (CNN을 이용한 TCX 모드 기반의 주파수 정보 복원 기술)

  • Kim, Jaewon;Shin, Seong-Hyeon;Han, Seokhyeon;Choi, Hyunkook;Kim, Sangmin;Park, Hochong
    • Proceedings of the Korean Society of Broadcast Engineers Conference
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    • pp.340-342
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    • 2020
  • 본 논문에서는 CNN을 이용한 TCX 모드 기반의 주파수 정보 복원 기술을 제안한다. TCX 모드는 USAC에서 지원하는 음성을 위한 양자화 기술로 부호화 과정에서 포락선을 평탄화한 후 양자화한다. 이러한 평탄화 동작은 주파수 정보 간의 상관도를 높여 네트워크의 학습을 쉽게 만들고 예측 성능을 높인다. 제안하는 방법은 청각 심리 모델 기반으로 구현된 주파수 정보 복원 방법에 TCX 모드 기반의 양자화 방법을 적용하여 일부 주파수 정보만을 사용해 손실된 주파수 정보를 복원한다. 제안하는 방법을 사용해 기존 방법보다 낮은 학습 오차를 얻었고 최적화 되지 않은 조건에서 동등한 음질을 얻었다.

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Matching Pursuit Estimation and Quantizer Design for Sinusoidal Model-based Coder (정현파 모델 부호화기를 위한 MP(Matching Pursuit) 알고리즘과 파라미터 양자화기)

  • Ahn Yeong-Uk;Jeong Gyu-Hyeok;Kim Jong-Hak;Yang Yong-Ho;Lee In-Sung
    • The Journal of the Acoustical Society of Korea
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    • v.24 no.7
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    • pp.402-409
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    • 2005
  • In this paper. we propose a coding method using a matching pursuit algorithm in a strongly periodic highband signal. Also. we propose an efficient quantizer for the estimated parameters : spectral magnitude and phase. Based on the error concealment principle and sinusoidal model. the MP algorithm requires the high-precision pitch period estimation. To estimate more accurate pitch period. the refined pitch obtained from lowband speech is used. which increases the efficiency of bit allocation. The spectral magnitude parameters are quantized by the method which is combined with MDCT (Modified Discrete Cosine Transform) and multi-stage structure. The spectral phase quantizer uses the $2{\pi}$ modular characteristic of phases and the weighted function by spectral magnitudes. To evaluate the efficiency of the proposed method. we applied it to analysis-by-synthesis system. Furthermore we suggest the possibillity of scalable wideband speech codecs based on band-split structure.

Human Visual Perception-Based Quantization For Efficiency HEVC Encoder (HEVC 부호화기 고효율 압축을 위한 인지시각 특징기반 양자화 방법)

  • Kim, Young-Woong;Ahn, Yong-Jo;Sim, Donggyu
    • Journal of Broadcast Engineering
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    • v.22 no.1
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    • pp.28-41
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    • 2017
  • In this paper, the fast encoding algorithm in High Efficiency Video Coding (HEVC) encoder was studied. For the encoding efficiency, the current HEVC reference software is divided the input image into Coding Tree Unit (CTU). then, it should be re-divided into CU up to maximum depth in form of quad-tree for RDO (Rate-Distortion Optimization) in encoding precess. But, it is one of the reason why complexity is high in the encoding precess. In this paper, to reduce the high complexity in the encoding process, it proposed the method by determining the maximum depth of the CU using a hierarchical clustering at the pre-processing. The hierarchical clustering results represented an average combination of motion vectors (MV) on neighboring blocks. Experimental results showed that the proposed method could achieve an average of 16% time saving with minimal BD-rate loss at 1080p video resolution. When combined the previous fast algorithm, the proposed method could achieve an average 45.13% time saving with 1.84% BD-rate loss.

Adaptive rate control for video communication (동영상 통신을 위한 적응 비트율 제어)

  • 김학수;정연식
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.24 no.9A
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    • pp.1383-1391
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    • 1999
  • This paper presents a rate control method that minimizes global distortion under given target bit rates for video communication. This method makes the quality of reconstructed images better than that of the conventional ones based on R-D model at the same bit rates. Given a set of quantizers, a sequence of macroblocks to be quantized selects the optimal quantizer for each macroblock so that the total cost measure is minimized and the finite buffer is never in overflow. To solve this problem we provide a heuristic algorithm based on Lagrangian optimization using an operational rate-distortion framework and a quantization method follows H.263recommendation.

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