• Journal of Broadcast Engineering
• /
• 제18권4호
• /
• pp.631-642
• /
• 2013

For the emerging High Efficiency Video Coding (HEVC) standard, a fast transform unit (TU) decision method is proposed. HEVC defines the TU representing a region sharing the same transformation, and it allows a residual block to be split into multiple TUs recursively to form a quadtree. By using the quadtree of TUs, HEVC supports various transform sizes from $4{\times}4$ to $32{\times}32$. The various sizes of TUs can provide a good coding efficiency, whereas this may increase encoding complexity dramatically. In the assumption that a TU with highly compacted energy is unlikely to be split, the proposed method determines TU sizes according to the position of the last non-zero transform coefficient. In the experimental results, the proposed method reduced 18% encoding run time with the negligible coding loss of 0.7% BD-rate for the Random_access case.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• 제4권3호
• /
• pp.263-269
• /
• 2003

This paper focuses on lossy medical image compression methods for medical images that operate on three-dimensional(3D) irreversible integer wavelet transform. We offer an application of the Set Partitioning in Hierarchical Trees(SPIHT) algorithm〔l-3〕to medical images, using a 3-D wavelet decomposition and a 3-D spatial dependence tree. The wavelet decomposition is accomplished with integer wavelet filters implemented with the lifting method, where careful scaling and truncations keep the integer precision small and the transform unitary. As the compression rate increases, the boundaries between adjacent coding units become increasingly visible. Unlike video, the volume image is examined under static condition, and must not exhibit such boundary artifacts. In order to eliminate them, we utilize overlapping at axial boundaries between adjacent coding units. We have tested our encoder on medical images using different integer filters. Results show that our algorithm with certain filters performs as well. The improvement is visibly manifested as fewer ringing artifacts and noticeably better reconstruction of low contrast.

• Journal of Information Processing Systems
• /
• 제18권2호
• /
• pp.235-244
• /
• 2022

Many new techniques have been adopted in HEVC (High efficiency video coding) standard, such as quadtree-structured coding unit (CU), prediction unit (PU) partition, 35 intra-mode, and so on. To reduce computational complexity, the paper proposes two optimization algorithms which include fast CU depth range decision and fast PU partition mode decision. Firstly, depth range of CU is predicted according to spatial-temporal correlation. Secondly, we utilize the depth difference between the current CU and CU corresponding to the same position of adjacent frame for PU mode range selection. The number of traversal candidate modes is reduced. The experiment result shows the proposed algorithm obtains a lot of time reducing, and the loss of coding efficiency is inappreciable.

• Journal of the Chungcheong Mathematical Society
• /
• 제21권4호
• /
• pp.527-532
• /
• 2008

We compare a coding space which has an ultra metric with the unit interval which has an associated generalized dyadic expansion. The two spaces are not homeomorphic but dimensionally equivalent in the sense that the Hausdorff and packing dimensions of the corresponding distribution sets in the two spaces coincide.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• 제22권5호
• /
• pp.1083-1096
• /
• 1997

To implement satellite B-ISDN/ATM network, it needs to gurantee reliable transport via satelite in the poor BER environment. So, it requires to use channel coding (FEC:Forward Error Correction) schemes for improvement of BER performance, but these coding effects evoke burst errors and degradation of the QoS. Therefore we have to investigate new algorithm that compensates these weaknesses. We consider convolutional coding and concatenated coding among FEC schemes as FEC for satellite transmission and choose different compensational algorithm by the error characteristics of the using type of FEC. In using concatenated coding, this paper proposes the satellite system structure for interconnection to the terrestrial network and proposes the channel coding algorithm for improvement of transmission performances. We execute performance evaluation of the proposed algorithm by computer simulation. In detail, we propose 4 types of application ATM cell to the block coding(Reed-Solomon) and propose the new 55 byte ATM cell that enforces the error correction capability of cell header by the BCH coding. Then we propose the outer interleaverand the cell unit interleaver that evoke maximum coding effect of BCH code.

• Proceedings of the Korean Society of Broadcast Engineers Conference
• /
• 한국방송∙미디어공학회 2018년도 하계학술대회
• /
• pp.270-271
• /
• 2018

본 논문에서는 새로이 시작된 비디오 압축 표준인 VVC(Versatile Video Coding)의 인-루프(in-loop) 필터링을 위한 CNN 구조를 제안한다. 제안하는 CNN 구조는 복호화된 영상을 입력으로 하고 원본 영상과 복호화된 영상의 오차를 손실함수로 사용하여 학습을 진행한다. 또한, 비디오 부호화에서의 다양한 크기의 CU(Coding Unit)를 고려한 다양한 크기의 컨볼루션 필터를 사용하여 특징을 추출하는 구조에 기반하고 있다. 실험을 통하여 제안한 CNN 기반의 필터링이 VVC 의 시험모델인 VTM(VVC Test Model)의 인-루프 필터링의 성능을 개선할 수 있음을 확인하였다.

• Proceedings of the Korean Society of Broadcast Engineers Conference
• /
• 한국방송공학회 2011년도 하계학술대회
• /
• pp.173-176
• /
• 2011

현재 표준화가 진행 중인 HEVC (High-efficiency video coding) 는 기존의 동영상 표준과 마찬가지로 여러 기술들이 혼합된 하이브리드 영상 부호화 프레임 워크 구조를 따르고 있다. 특히, 다양한 크기의 부호화 단위 (Coding Unit : CU), 예측단위 (Prediction Unit : PU), 변환 단위 (Transform Unit : TU) 의 사용으로 인해 HD 이상의 영상에 대하여 기존의 H.264/AVC 보다 약 40%의 압축률 향상을 보이고 있다. 하지만 그로 인하여 부호화기 복잡도가 약 3 배 이상 증가하는 것으로 나타났으며 이는 실시간 부호화가 요구되는 분야에서 큰 문제가 될 것이다. 본 논문은 HEVC 부호화기 복잡도를 낮추기 위하여 최적의 CU 를 결정하는 과정 중 조기에 CU 를 결정하는 고속 CU 결정 방법을 소개한다. 실험 결과, 제안된 방법은 HM과 비교하여 PSNR (Peak Signal to Noise Ratio) 의 손실이 거의 없이 최대 약 58%의 부호화 시간을 절약하였다.

• Proceedings of the KSRS Conference
• /
• 대한원격탐사학회 2004년도 Proceedings of ISRS 2004
• /
• pp.457-459
• /
• 2004

The Channel Coding Unit (CCU) is an integral component of Payload Data Transmission System (PDTS) for the Multi-Spectral Camera (MSC) data. The main function of the CCU is channel coding and encryption. CCU has two channels (I & Q) for data processing. The input of CCU is the output of DCSU (Data Compression & Storage Unit). The output of CCU is the input of QTX which modulate data for RF communication. In this paper, there are the overview, short H/W description and operation concept of CCU.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• 제40권4호
• /
• pp.659-665
• /
• 2015

Recent studies on network coding scheme for increasing transmission efficiency of the network has been actively conducted. In this paper, we apply RLNC in sub-packet unit and propose a joint scheme of sub-packet level network coding and LDPC code. The proposed method can have similar ability of network coding and obtain further error correction capability. The simulation results show that the proposed one enhances error correction capability compared to the case using only LDPC when extra packets are received.

• Journal of Broadcast Engineering
• /
• 제16권6호
• /
• pp.1036-1046
• /
• 2011

MPEG and VCEG have constituted a collaboration team called JCT-VC(Joint Collaborative Team on Video Coding) and have been developing HEVC(High Efficiency Video Coding) standard. All transform coefficients in a TU(Transform Unit) have been equally quantized according to the quantization and inverse quantization method which is used in HEVC standard. Such an equal quantization is not efficient because the transformed coefficients in the TU are not eqully distributed. Furthermore, the quantized coefficients which is positioned in later scanning order cannot be efficient due to the entropy scanning method. We suggest an algorithm that transform coefficients are quantized at different values according to the position in TU considering a scanning order of entropy encoding to improve the coding efficiency. The principle of this algorithm is that quantization and inverse quantization are carried out according to the scanning order which is in accordance with the statistical characteristic of distribution of quantized transform coefficients. The proposed algorithm shows on the average of 0.34% Y BD-rate compression rate improvement.