• Proceedings of the Korea Information Processing Society Conference
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• 2002.11a
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• pp.783-786
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• 2002

멀티미디어 컨텐트의 실시간 전송은 인터넷에서 중요한 기술영역으로 나타나고 있다. 본 논문에서는 MPEG-4 표준에서 채택된 FGS(Fine Granualrity Scalability)를 이용한 계층적 비디오 부호화 방법의 효율성 향상을 위한 방법을 제시하였다. MPEG-4 FGS는 인터넷에서 이용되는 다양한 특성의 단말기들과 대역폭 변동에서 유연성 있는 기술이다. 일반적인 계층 비디오 부호화 기법보다 PSNR값이 평균 1$\sim$2dB정도 높게 나타난다. 그러나 단일 계층 부호화 방법에 비해서는 효율성이 낮게 나타난다. 제안된 방법에서는 이런 FGS의 효율성을 높이기 위한 방법으로 시간 스케일러빌리티를 갖는 FGST(FGS temporal scalability)층을 적용하였다. 기본계층은 일반적인 FGS 부호화에 의해 이루어지고 상위계층 부호화로 시간적 스케일러빌리티를 갖는 FGST를 이용한다. 실험은 프레임율 10 fbs의 container와 mobile 영상에 대해 이루어졌고 두 영상 모두에 대해 FGS 부호화만을 적용하는 경우보다 상위계층으로서 FGST를 이용하는 경우 상당한 효율성 향상이 있음을 보인다.

• Journal of Broadcast Engineering
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• v.16 no.1
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• pp.144-154
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• 2011

In this paper, we propose a parallel LDPCA encoding method for fast transform-domain Wyner-Ziv video encoding which is suitable in an ultra fast and low power video encoding. The conventional transform-domain Wyner-Ziv video encoding performs LDPCA channel coding of quantized transform coefficients in bitplane-serial fashion, which takes about 60% of total encoding time, and this computational complexity becomes severer as the bitrate increases. The proposed method binds several bitplanes into one packed message and carries out the LDPCA encoding in parallel. The proposed LDPCA encoding method improves the encoding speed by 8 ~ 55 times. In the experiment, the proposed Wyner-Ziv encoder can encode 700 ~ 2,300 QCIF size frames per second with GOP=64. The method can be applied to the pixel-domain Wyner-Ziv encoder using LDPCA, and has a wide scope of application.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.25 no.4B
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• pp.743-754
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• 2000

In this paper, we propose wavelet transform image compression method using shuffling and bit plane correlation. Proposed method is that original image decompose into multiresolutions using biorthogonal wavelet transform with linear phase response property and decomposed subbands are classified by maximum classification gain. And classified data sets in each subband are quantized using arbitrary set optimum bit allocation method. Quantized data sets in each subband are shuffled and context based bit plane arithmetic encoded .In context based bit plane arithmetic encoding, the context for each subband is not assigned uniformly, but assigned according to maximum correlation direction. Our results are comparable, or superior for some images at low rates, to published state-of-the-art coders.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2005.11a
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• pp.43-46
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• 2005

H.264/AVC 동영상 부호화 표준에서는 새로운 부호화 도구들이 추가되었으며 이를 통해 이전의 동영상 표준과 비교하여 높은 압축 효율을 가진다. 특히, VBS(Variable Blok Size)와 다중 참조 프레임의 사용으로 H.264내의 매크로블록은 이전의 부호화 표준들에 비하여 보다 많은 정보들을 포함한다. H.264 부호화 표준에서는 하나의 매크로블록이 최대 16개까지의 서로 다른 움직임 벡터를 가질 수 있으며 최대 4개의 서로 다른 참조프레임을 가질 수 있다. 또한 다양한 블록크기로의 움직임 추정을 하며 이는 매크로블록 모드로서 정의된다. 따라서 H.264내의 매크로블록은 기존의 동영상 부호화 표준보다 많은 움직임 벡터를 가질 뿐만 아니라 기존에는 없던 참조프레임과 매크로블록 모드의 정보를 새로이 포함하고 있다. 본 논문은 H.264 부호화 표준의 특성을 고려하여 매크로블록이 포함하고 있는 다양한 크기의 움직임 벡터 및 참조 프레임뿐 아니라 주변 매크로블록들의 모드를 이용하여 손실된 매크로블록에 대해 에러를 은닉함으로써 매크로블록이 포함하고 있는 정보를 최대한 활용하는 효율적인 에러은닉 알고리즘을 제안한다.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.4 no.4
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• pp.434-440
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• 2003

Since Jacquine introduced the image coding algorithm using fractal theory, many fractal image compression algorithms providing good quality at low bit rate have been proposed by Fisher and Beaumount et al.. But a problem of the previous implementations is that the decoding rests on an iterative procedure whose complexity is image-dependent. This paper proposes an iterative-free fractal image decoding algorithm to reduce the decoding time. In the proposed method, under the encoder previously with the same codebook image as an initial image to be used at the decoder, the fractal coefficients are obtained through calculating the similarity between the codebook image and an input image to be encoded. As the decoding process can be completed with received fractal coefficients and predefined initial image without repeated iterations, the decoding time could be remarkably reduced.

• Proceedings of the Korea Information Processing Society Conference
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• 2004.05a
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• pp.757-760
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• 2004

동영상은 포함하고 있는 정보량이 아주 많기 때문에, 영상처리기술 중에서도 데이터 압축기술은 대단히 중요하다. 본 논문에서는 DCT 이 외의 수법을 이용할 때의 동영상의 부호화에 대하여 검토하고, 특이값 전개에 주목한다. 이 방식이 DCT가 갖는 문제점을 모두 해결할 수 있는 것은 아니지만, 다른 방식에서의 영상부호화의 가능성을 보이고자 한다.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.37 no.1
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• pp.66-75
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• 2000

In this paper, we present the efficient image transmission system using designed source-channel combined coder in W-CDMA mobile communication system. In proposed schemes, we decompose the wavelet transformed hierarchical band-images into some types of different size blocks which have different properties in error sensitivity. The RS(Reed-Solomon) coder with different coding rate is used for each decomposed source blocks which has different importance. In addition, we combine retransmitted error frames in Truncated Hybrid Type I ARQ. The proposed algorithm shows efficient image transmission methods because it is not much degraded in PSNR compared with the existing not combined source-channel coder in erroneous wireless channel.

• Proceedings of the Korea Contents Association Conference
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• 2003.11a
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• pp.328-332
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• 2003

Since Jacquine introduced the image coding algorithm using fractal theory, many fractal image compression algorithms providing good quality at low bit rate have been proposed by Fisher and Beaumount et al.. But a problem of the previous implementations is that the decoding rests on an iterative procedure whose complexity is image -dependent. This paper proposes an iterative-free fractal image decoding algorithm to reduce the decoding time. In the proposed method, under the encoder previously with the same codebook image as an initial image to be used at the decoder, the fractal coefficients are obtained through calculating the similarity between the codebook image and a input image to be encoded. As the decoding process can be completed with received fractal coefficients and predefined initial image without repeated iterations, the decoding time could be remarkably reduced.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.22 no.5
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• pp.907-914
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• 1997

The conventional decoding procedure for the images encoded using fractal contractive transformation algorithms is performed by applying the transformations iteratively for an arbirary initial image. In this paper, we showed that the atractor image can be obtained analytically when the image is encoded using the fractal algorithm proposed by Monro and Dudbridge, in which the corresponding domain block for a range block is fixed. Using the analytical formula, we can obtain the attractor image without iteration procedure. Computer simulation results for various test images show that we can increase the image decoding speed by more than five times when we use the analytical formula compared to the previous iteration methods. Also we confirmed that the real time decoding by software on PD is possible for the moving picture with QCIF formats.

• Journal of the Korean Institute of Telematics and Electronics T
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• v.35T no.2
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• pp.35-38
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• 1998

We need the packet transmission of voice, data and video according to the development of ATM technology and packet network. In ATM, packet is parted to the constant length data, we called cell, the method is needed to minimize data loss. Because over ATM, we discard error cell without correction in transmission. So, about video, there is layered coding method. We simulated the coding using wavelet transform, which is structurally layed coded, so need not the additional coder.