• IEIE Transactions on Smart Processing and Computing
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• v.5 no.5
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• pp.323-326
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• 2016

High Efficiency Video Coding (HEVC) adopts intra transform skip mode, in which a residual block is directly quantized in the pixel domain without transforming the block into the frequency domain. Intra transform skip mode provides a significant coding gain for screen content. However, when intra-prediction errors are not transformed, the errors are often correlated along the intra-prediction direction. This paper introduces a residual differential pulse code modulation (DPCM) method for the intra-predicted and transform-skipped blocks to remove redundancy. The proposed method performs pixel-by-pixel residual prediction along the intra-prediction direction to reduce the dynamic range of intra-prediction errors. Experimental results show that the transform skip mode's Bjøntegaard delta rate (BD-rate) is improved by 12.8% for vertically intra-predicted blocks. Overall, the proposed method shows an average 1.2% reduction in BD-rate, relative to HEVC, with negligible computational complexity.

• Journal of the Institute of Electronics and Information Engineers
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• v.53 no.6
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• pp.130-136
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• 2016

HEVC (High Efficiency Video Coding) extension considers screen content as one of its main candidate sources for encoding. Among the tools already included in HEVC version 1, the technique of using transform skip mode allows transform to be skipped and to perform quantization process only. It is known to improve video coding efficiency for screen contents which are characterized to have much high frequency energy. But encoding complexity increases since its encoder should decide whether transform should be used or not in each $4{\times}4$ transform block. Based on statistical correlation between IBC (Intra block copy) and transform skip modes both of which are known effective in screen contents, this paper proposes a combined method of the fast transform skip mode decision and a modified transform skip signaling which signals transform_skip_flag at CU level as a representative transform skip signal. By simulation, the proposed method is shown to reduce encoding time of $4{\times}4$ transform blocks by about 32%.

• IEIE Transactions on Smart Processing and Computing
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• v.3 no.6
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• pp.388-392
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• 2014

This paper proposes an early termination method of a block vector search for fast encoding of high efficiency video coding (HEVC) screen content coding (SCC). In the proposed algorithm, two blocks indicated by two block vector predictors (BVPs) were first employed as an intra block copy (IBC) search. If the sum of absolute difference (SAD) value of the block is less than a threshold defined empirically, an IBC BV search is terminated early. The initial threshold for early termination is derived by statistical analysis and it can be modified adaptively based on a quantization parameter (QP). The proposed algorithm is evaluated on SCM-2.0 under all intra (AI) coding configurations. Experimental results show that the proposed algorithm reduces IBC BV search time by 29.23% on average while the average BD-rate loss is 0.41% under the HEVC SCC common test conditions (CTC).

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.10 no.10
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• pp.5074-5094
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• 2016

Screen splitting is one of the fundamental tasks in different methods including video and image compression, screen classification, screen content coding and the like. These methods in turn support various applications in data communications, remote screen sharing, remote desktop delivery to assist teaching-learning, telemedicine, Desktop as a Service etc. In the literature we find systems requiring splitting assumes a fixed size split that do not change dynamically, also there is no analysis why that split is chosen in terms of performance. By doing mathematical analysis this paper first finds the efficient splitting schemes that can be easily automated to make a system adaptive. Thereafter, taking the screen motion detection as a case study, it demonstrates the effects of various splitting methods on motion detection performance. The simulation results clearly shows how classification performances varies with different splitting which will facilitate to choose the best splitting for a specific application scenario as well as making the system adaptive by providing dynamic splitting.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2016.06a
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• pp.246-249
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• 2016

본 논문에서는 화면 내 블록 카피 (IntraBC: Intra Block Copy) 예측 기술의 압축 성능 분석과 향상된 해쉬 기법을 통한 HEVC (High Efficiency Video Coding) 스크린 콘텐츠 코딩 성능 기법을 제안한다. 현재 SCM (Screen Content Coding Test Model) 에 채택 된 화면 내 블록 카피 기술에서는 $16{\times}16$ 블록에는 1차원 탐색을 수행하고 $8{\times}8$블록에서는 해쉬기반 전역 탐색을 수행하여 해쉬가 일치하는 블록들과 RD-Cost를 수행한다. 현재의 해쉬기반 전역탐색에는 기울기 (Gradient) 위주의 해쉬 구성으로 인해 해쉬가 고르게 분포하지 않아, RD-Cost 수행횟수가 과도하게 많아지는 문제가 있다. 제안하는 방법은 전역적 화면 내 블록 카피의 해쉬 구성 방법을 개선함으로써, 기존 SCM-6.1 대비 0.46%의 BDBR 향상을 확인하였다.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2014.11a
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• pp.177-179
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• 2014

컴퓨터 그래픽의 발달 및 다양한 멀티미디어 기기들의 보급이 증가함에 따라 스크린 콘텐츠 영상에 대한 수요가 증가하고 있다. 자연영상과 다른 특성을 지닌 스크린 콘텐츠 영상의 효율적인 압축을 위하여, 기존의 High Efficiency Video Coding (HEVC)의 SCC (screen content coding) 에서는 스크린 콘텐츠 영상을 위한 새로운 예측 기술이 추가되었다, 추가된 대표적인 예측 기술로 화면 내 블록 카피 (IBC: intra block copy) 기술과 팔레트 모드 등이 있다. 본 논문에서는 스크린 콘텐츠 코딩의 부호화 효율 향상 연구에 앞서, 스크린 콘텐츠 코딩에서 높은 부호화 효율을 보이는 화면 내 블록 카피 기술에 대하여 소개하고 화면 내 블록 카피 기술의 부호화 특성 및 블록 벡터 예측 기법에 대한 분석을 수행한다. 또한, 이러한 분석 결과를 토대로 화면 내 블록 카피 기술의 성능 향상을 위한 방법을 제시한다.

• Journal of Broadcast Engineering
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• v.25 no.3
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• pp.353-361
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• 2020

VVC (Versatile Video Coding) is a new video compression technique that is being standardized, and it supports HD / UHD / 8K video, and High Dynamic Range (HDR) video with a goal of approximately 2 times higher coding efficiency than the conventional HEVC. It also aims to support a variety of functionalities such as screen content coding, adaptive resolution changes, and independent sub-pictures. In this paper, we investigate the signaling process of intra prediction mode first, and develop an effective coding method of the chroma intra prediction mode. In case of the DM mode, the proposed method simplifies the prediction mode of the chorma intra prediction mode when referring to the angular mode of the luminance block. It can improve coding efficiency of the chroma intra prediction mode, and the proposed process can also consider the size of the block in order to further improve its coding efficiency.

• Journal of Korea Multimedia Society
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• v.24 no.8
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• pp.1178-1183
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• 2021

Based on the camera movement on image expression and grammar, this study intended to analyze the characteristics of image expression filmed and broadcasted by drones. This study analyzed drone images using the movement characteristics of existing video cameras as a coding nomenclature. These were intended to examine the differences from existing video grammar and their implications. This study conducted a content analysis using the entire population of drone news footage broadcast for four years in 2015, 2016, 2017 and 2018 by TV Chosun. The size of the screen, camera work, duration of the shot, camera angle, etc. were selected and analyzed. As a result, the drone camera work showed that it uses the most dolly shots in the case of camera movement, followed by the drone camera movement in the order of pan and tilt shots. For zoom, the frequency of use was the smallest. In addition, this study analyzed the size of the screen, duration of the shot, and camera angle of drone. Analysis shows that drones use certain camera movements most frequently, and unlike grandiose modifiers such as "extension of human gaze," drone remains as a supplementary means to enhance the traditional media expression.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2020.11a
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• pp.49-52
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• 2020

MPEG-I(Immersive) 그룹에서는 몰입형 미디어 영상처리 표준화의 일환으로 마이크로렌즈를 통한 다시점 영상 처리 기술인 Dense Light Field에 대한 성능 탐색을 진행하고 있다. 본 논문에서는 MPEG-I에서 정의된 라이트 필드 시퀀스에 대해 versatile video codec(VVC)에 대한 압축 성능 분석을 시행하였으며, 또한 렌즈렛(Lenslet) 형태의 특정적인 이미지 정보를 효율적으로 압축하기 위한 스크린 콘텐츠 코딩 툴의 효율 비교를 진행하였다. 또한 렌즈렛 영상에서의 화면 내 블록 카피(intra block copy) 기법이 선택되는 비율을 확인하고, 화면 내 블록 카피 기법을 통해 렌즈렛 영상이 효율적으로 압축될 수 있음을 보였다.