• Journal of Broadcast Engineering
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• v.15 no.4
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• pp.563-581
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• 2010

In this paper, we perform subjective visual quality assessments on UHD video for UHD TV services and analyze the assessment results. Demands for video services have been increased with availabilities of DTV, Internet and personal media equipments. With this trend, the demands for high definition video have also been increasing. Currently, 2K-HD ($1920{\times}1080$) video have been widely consumed over DTV, DVD, digital camcoders, security cameras and other multimedia terminals in various types, and recently digital cinema contents of 4K-UHD($3840{\times}2160$) have been popularly produced and the cameras, beam projects, display panels that support for 4K-UHD video start to come out into multimedia markets. Also it is expected that 4K-UHD service will appear soon in broadcasting and telecommunications environments. Therefore, in this paper, subjective assessments of visual quality on resolutions, color formats, frame rates and compression rates have been carried to provide basis information for standardization of signal specification of UHD video and viewing environments for future UHDTV. As the analysis on the assessments, UHD video exhibits better subjective visual quality than HD by the evaluators. Also, the 4K-UHD test sequences in YUV444 shows better subjective visual quality than the 4K-UHD test sequences in YUV422 and YUV420, but there is little perceptual difference on 4K-UHD test sequences between YUV422 and YUV420 formats. For the comparison between different frame rates, 4K-UHD test sequences of 60fps gives better subjective visual quality than those of 30fps. For bit-depth comparison, HD test sequences in 10-bit depth were little differentiated from those in 8-bit depth in subject visual quality assessment. Lastly, the larger the PSNR values of the reconstructed 4K-UHD test sequences are, the higher the subjective visual quality is. Against the viewing distances, the differences among encoded 4K-UHD test sequences were less distinguished in longer distances from the display.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.42 no.1
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• pp.43-50
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• 2005

We proposed a method for embedding coded binary data into EZW bitstreams and extracting embedded data from EZW bitstreams using the traditional EZW decoder. EZW coder have two passes. The first pass, the dominant pass have four symbols, P, N, IZ, ZTR. The second pass is sub-ordinary pass which specifies the value of symbol. In the proposed methods, we use ZTR symbol in the dominant pass. We embed watermark into ZTR symbol in the highest frequency band which original image is transferred by wavelet transform. The proposed digital watermarking method shows good properties for robustness in the low bit rate. Accordingly, based on the proposed digital watermarking, video and 3D image watermarking will become a new area for research in the near future.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.43 no.6 s.312
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• pp.97-104
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• 2006

The state-of-the-art H.264/AVC standard was designed for the lossy video coding so that it could not yield the best performance for lossless video coding. In this paper, we propose two efficient intra lossless coding methods by embedding a pixel-wise prediction into the H.264/AVC. One is based on the pixel-wise prediction for the residual signal of the H.264/AVC intra Prediction and the other suggests a newly additional intra prediction mode for the conventional intra prediction. We found that the proposed lossless coding algorithms could achieve approximately $12%{\sim}25%$ more bit saving compared to the H.264/AVC FRExt high profile for several test sequences in terms of a compression ratio.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.14 no.2
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• pp.383-393
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• 2010

DVC (Distributed Video Coding) allows us to explore the video statistics at the decoder side, resulting in a less complex encoder and more complex decoder. In this approach, it is important to generate a good prediction to the current Wyner-Ziv frame, called side information, which plays a crucial role in the overall performance of a DVC system. Conventional MCFI (motion compensated frame interpolation) techniques, which explore temporal correlations between neighbor frames of the current frame, preform the block-based or object-based motion estimation, but, they do not include the basis frame for the Wyner-Ziv frame. This paper proposes an efficient way to get better side information, by finding the average frame between neighbor frames and by comparing adaptively the candidate blocks. Through computer simulations, it is shown that the proposed method can improve the performance up to 0.4dB and provide better subjective and objective visual qualities in Wyner-Ziv CODEC.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2019.11a
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• pp.30-31
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• 2019

최근 들어 다양한 초 고화질 스트리밍 서비스의 보급과 통신기술의 급격한 발전에 따라 고화질 비디오 신호를 포함하는 멀티미디어 데이터의 이용과 전송의 중요성이 급속도로 증가하고 있다. 또한, 동시에 동영상에 대한 수요도 지속적으로 증가하고 있어, 더욱 효과적인 동영상의 압축기법이 요구되고 있는 실정이다. 본 논문에서는 최근 VVC(Versatile Video Coding) 표준화를 위하여 채택한 기술인 변환 생략 기술의 적용범위를 확장하여 기존의 방법처럼 휘도 채널에 적용하는 것뿐만 아니라 특정한 조건 하에서는 동일한 방법을 색차 채널에도 적용하도록 하여 압축 효율을 향상하는 방법을 연구하였다. 실험결과, 기존 VVC 방법 대비 BDBR 측면에서 (두번째는 SCC 영상의 실험결과) All Intra 방법에 대하여 Y(0.00%, 0.03%), U(-0.01%, -0.01%) 그리고 V(0.02%, -0.04%), Random access 방법에 대하여 Y(0.00%, 0.01%), U(-0.01%, -0.11%)그리고 V(0.03%, -0.15%)의 결과를 얻을 수 있었다.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2015.07a
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• pp.470-473
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• 2015

본 논문에서는 MPEG 에서 현재 Type-1 동영상 표준을 위해 연구를 진행하고 있는 인터넷 비디오 코딩(Internet Video Coding, IVC)의 압축 성능에 대한 평가 방법 및 결과를 다룬다. 다년간의 연구로 IVC 의 성능은 매우 개선되어 왔으나, 산업이 원하는 수준에 도달했는지를 검증하기 위해서는 타 동영상 코덱과의 비교 평가 역시 필요하다. 이를 위하여, AVC/H.264 를 기반으로 Type-1 표준화를 진행해온 Web Video Coding(WebVC)의 인코더와 IVC Test Model 10.0 을 압축 성능 관점에서 객관적으로 비교 평가함으로써, IVC 의 부호화 성능의 뛰어남을 보이고자 한다. 또한, 상용화된 AVC/H.264 High Profile 과도 비교함으로써, IVC 의 객관적인 성능을 확인하고자 한다. 특별히, MPEG 내에서 결정한 시각적 비교 조건(Visual comparison condition)에 입각한 목표 비트율 및 양자화 변수 조건에 맞추어 평가한다.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2020.11a
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• pp.158-159
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• 2020

초 고화질 영상의 등장과 동영상 스트리밍 서비스의 폭발적인 이용증가로 고품질로 영상을 압축할 수 있는 기술의 중요성이 크게 증가하고 있다. 본 논문에서는 VVC 차세대 비디오 부호화기술에 따라 색차 블록의 화면 내 예측 시 정확한 예측각도를 측정하여 압축 성능을 더욱 향상시키는 방법을 연구하였다. 실험결과, 기존 VVC 방법 대비 BDBR(Bjontegaard Delta Bit Rate) 측면에서 AI(All Intra) 조건의 경우, Y(-0.01%), Cb(-0.07%), Cr(-0.05%)의 성능변화를 얻을 수 있었다.

• Journal of Broadcast Engineering
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• v.7 no.4
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• pp.317-326
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• 2002

The adaptive coding schemes in H.264 standardization provide a significant ceding efficiency and some additional features like error resilience and network friendliness. The variable block size motion compensation using multiple reference frames is one of the key H.264 coding elements to provide main performance gain, but also the main culprit that increases the overall computational complexity. For this reason, this paper proposes a selective motion estimation algorithm based on variable block size for fast motion estimation in H.264. After we find the SAD(Sum of Absolute Difference) at initial points using diamond search, we decide whether to perform additional motion search in each block. Simulation results show that the proposed method is five times faster than the conventional full search in case of search range $\pm$32.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.34 no.8C
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• pp.790-800
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• 2009

For the improvement of coding efficiency, the H.264/AYC standard uses new coding tools such as 1/4-pel-accurate motion estimation, multiple references, intra prediction, loop filter, variable block size etc. Using these coding tools, H.264/AYC has achieved significant improvements from rate-distortion point of view compared to existing standards. However, the encoder complexity was greatly increased due to these coding tools. We focus on the complexity reduction method of intra macroblock mode selection. The proposed algorithm for fast intra mode selection calculates the edge activity in transform domain, and performs fast encoding of intra frame in H.264/AYC through the fast prediction mode selection of intra4x4 and chrominance blocks. Simulation results show that the proposed method saves about 59.76% for QCIF sequences and 65.03% for CIF sequences of total encoding time, while bitrate increase and PSNR decrease are very small.

• Journal of Broadcast Engineering
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• v.20 no.1
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• pp.16-25
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• 2015

Even if the demands for ultra-high-quality multimedia contents are increasing, it is difficult to produce, encode, play and transport ultra-high-quality contents under the existing broadcasting environment. By the reason, various technologies for the UHD contents have been developed in order to satisfy the user's needs. In this paper, we propose a design methodology of a broadcasting system, which consists of two parts, for UHD services with two parts. At the transmit part of the proposed system can encode a video into several layered-bitstreams hierarchically, and then transport each bitstream over heterogeneous networks. The receiver part can play the received video by composing the separated bitstreams. The proposed system can adaptively provide both HD and UHD contents according to user's reception conditions by using the heterogeneous networks.