• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2022.06a
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• pp.836-838
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• 2022

3D Point Cloud는 3D 콘텐츠를 더욱 실감 나게 표현하기 위한 데이터 포맷이다. Point Cloud 데이터는 3차원 공간상에 존재하는 데이터로 기존의 2D 영상에 비해 거대한 용량을 가지고 있다. 최근 대용량 Point Cloud의 3D 데이터를 압축하기 위해 V-PCC(Video-based Point Cloud Compression)와 같은 다양한 방법이 제시되고 있다. 따라서 Point Cloud 데이터의 원활한 전송 및 저장을 위해서는 V-PCC와 같은 압축 기술이 요구된다. V-PCC는 Point Cloud의 데이터들을 Patch로써 뜯어내고 2D에 Projection 시켜 3D의 영상을 2D 형식으로 변환하고 2D로 변환된 Point Cloud 영상을 기존의 2D 압축 코덱을 활용하여 압축하는 기술이다. 이 V-PCC로 변환된 2D 영상은 기존 2D 영상을 전송하는 방식을 활용하여 네트워크 기반 전송이 가능하다. 본 논문에서는 V-PCC 방식으로 압축한 V3C 데이터를 방송망으로 전송 및 소비하기 위해 MPEG Media Transport(MMT) Packet을 만드는 패킷화 방안을 제안한다. 또한 Server와 Client에서 주고받은 V3C(Visual Volumetric Video Coding) 데이터의 비트스트림을 비교하여 검증한다.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2022.06a
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• pp.832-835
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• 2022

최근 딥러닝 네트워크의 피처 맵을 활용하여 머신 태스크를 수행하는 Collaborative Intelligence에 대한 관심이 증가하고 있다. CI 구조는 피처 맵을 전송함에 따라서 저사양 디바이스에서 딥러닝 기반의 머신 태스크 수행을 가능하게 하여 다양한 산업에서 활용될 것으로 기대되고 있다. 그러나 CI 구조에서 전송되는 피처 맵은 데이터 크기가 방대하기 때문에 전송에 있어 효율적인 피처 맵 압축이 필요하다. 이에 본 논문에서는 MPEG-VCM에서 제안된 리사이징 (resizing)과 보간법 (interpolation)을 활용하여 피처 맵을 압축하는 Feature Coding 기술에 대하여, 다양한 리사이징 및 보간 방법을 조합하여 가장 우수한 압축 성능 대비 머신 태스크 성능을 나타내는 조합을 실험을 통해서 확인하고자 한다.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2022.06a
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• pp.146-149
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• 2022

기존 RDO(Rate Distortion Optimization) 기반 압축 방식은 압축 성능에 초점을 두기 때문에 영상 내 인지 특성이 무시될 수 있다. 따라서 RoI(Region of Interest)을 기반으로 압축률을 조절하는 연구가 고안[1, 2, 3, 4] 되었으며, HVS(Human Visual System) 관점에서 영상 내 중요한 부분에 대해 더 높은 품질로 영상을 압축하는 연구가 대부분이다. 최근 인공지능 기술이 발전함에 따라 지능형 영상 분석에 대한 수요가 증가하고 있으며, 이에 따라 머신 비전을 위한 영상 부호화 및 효율적인 전송에 대한 필요성이 대두되고 있다. 본 논문에서는 VVC(Versatile Video Coding)의 dQP(delta Quantization Parameter)를 활용하여 RoI(Region of Interest) 기반압축 방법을 제안하고, 두가지의 RoI 추출 방식을 소개한다. Detectron2 Faster R-CNN X101-FPN [5]의 첫번째 탐지기를 통해 후보 영역 기반 RoI 을 추출하고, 두번째 탐지기를 통해 객체 기반 RoI 을 추출하여, 영상 내 객체 부분과 비객체 부분으로 나누어 서로 다른 압축률로 압축을 수행하였으며, 이에 따른 성능을 비교하고자 한다.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.47 no.6
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• pp.127-136
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• 2010

In multi-view video, illumination disharmony between neighboring views can occur on account of different location of each camera and imperfect camera calibration, and so on. Such discrepancy can be the cause of the performance decrease of multi-view video coding by mismatch of inter-view prediction which refer to the pictures obtained from the neighboring views at the same time. In this paper, we propose an efficient histogram-based prefiltering algorithm to compensate mismatches between the luminance and chrominance components in multi-view video for improving its coding efficiency. To compensate illumination variation efficiently, all camera frames of a multi-view sequence are adjusted to a predefined reference through the histogram matching. A Cosited filter that is used for chroma subsampling in many video encoding schemes is applied to each color component prior to histogram matching to improve its performance. The histogram matching is carried out in the RGB color space after color space converting from YCbCr color space. The effective color conversion skill that has respect to direction of edge and range of pixel value in an image is employed in the process. Experimental results show that the compression ratio for the proposed algorithm is improved comparing with other methods.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.13 no.4
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• pp.1830-1838
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• 2012

The intra prediction and the motion estimation of inter prediction occupy 70 ~ 80% of whole compression time in H.264/AVC. Compression efficiency has been higher, but complexity has increased and coding time has also increased much more. This paper proposes a block size decision method of the intra prediction and mode decision method which minimize the loss of video quality during the encoding and shorten the time spent. This paper, in addition, proposes an algorithm which determines the method of adaptive block mode for motion estimation of inter prediction. We investigated PSNR and the intra prediction and inter prediction of time-consuming calculations in order to measure video quality degradation and complexity through experiments. Consequently, when you use all three methods, these methods showed that average coding time is shortened as about 500 to 600ms in every frame in the case of all experimented videos, keeping video quality nearly similar, compared with existing methods of H.264.

• Journal of the Institute of Electronics Engineers of Korea CI
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• v.38 no.2
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• pp.33-41
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• 2001

Currently, the compression is one of the most important technology in multimedia society. Audio files arc rapidly propagated throughout internet Among them, the most famous one is MP-3(MPEC-1 Laver3) which can obtain CD tone from 128Kbps, but tone quality is abruptly down below 64Kbps. MPEC-II AAC(Advanccd Audio Coding) is not compatible with MPEG 1, but it has high compression of 1.4 times than MP 3, has max. 7.1 and 96KHz sampling rate. In this paper, we propose an algorithm that decreased the capacity of AAC encoding computation but increased the processing speed by optimizing psychoacoustic model which has enormous amount of computation in MPEG 2 AAC encoder. The optimized psychoacoustic model algorithm was implemented by C++ language. The experiment shows that the psychoacoustic model carries out FFT(Fast Fourier Transform) computation of 3048 point with 44.1 KHz sampling rate for SMR(Signal to Masking Ratio), and each entropy value is inputted to the subband filters for the control of encoder block. The proposed psychoacoustic model is operated with high speed because of optimization of unpredictable value. Also, when we transform unpredictable value into a tonality index, the speed of operation process is increased by a tonality index optimized in high frequency range.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.27 no.6A
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• pp.618-627
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• 2002

In processing images using 2 dimensional Discrete Wavelet Transform(2D-DWT), the method to process the pixels around the image boundary may affect the quality of image and the cost to implement in hardware and software. This paper proposed an effective method to treat the boundary pixels, which is apt to implement in hardware and software without losing the quality of the image costly. This method processes the 2-D image as 1-D array so that 2-D DWT is performed by considering the image with the serial-sequential data structure (Serial-Sequential Processing). To show the performance and easiness in implementation of the proposed method, an image compression codec which compresses image and reconstructs it has been implemented and experimented. It included log-scale fried quantizer, but the entropy coder was not implemented. From the experimental results, the proposed method showed the SNR of almost the same SNR(Signal to Noise Ratio) to the Periodic Expansion(PE) method when the compression ratio(excluding entropy coding) of 2:1, 15.3% higher than Symmetric Expansion(SE) method, and 9.3% higher than 0-pixel Padding Expansion(ZPE) method. Also PE method needed 12.99% more memory space than the proposed method. By considering only the compression process, SE and ZPE methods needed additional operations than the proposed one. In hardware implementation, the proposed method in this paper had 5.92% of overall circuit as the control circuit, while SE, PE, and ZPE method has 22%, 21,2%, and 11.9% as the control circuit, respectively. Consequently, the proposed method can be thought more effective in implementing software and hardware without losing any image quality in the usual image processing applications.

• Journal of Broadcast Engineering
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• v.2 no.2
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• pp.114-124
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• 1997

In object based coding, binary shape ccx:ling plays an important role by ccx:ling the outer shape of object. Here we propose a new shape ccx:ling tool, which enccx:les the outline of shape from a baseline. Different from 2-D (Vertex) shape ccx:ling algorithms. the proposed method encodeds the data that are extracted in a I-D fashion. The enccx:led data consist of the starting position, distance lists, and turning point lists. In the lossless ccx:ling mode, every contour pixel is input for ccx:ling, whereas variable sampling has been employed to enccx:le fewer contour pixels while preserving reasonable distortion. For interframe ccx:ling, a fast motion compensation was achieved by use of distance and turning point lists. Subjective viewing tests proved that the proposed method outperforms the current shape ccx:ling standard, CAE, in MPEG-4. In objective results for compression efficiency, the proposed method was significantly better in intraframe coding than CAE, whereas CAE was better in interframe ccx:ling.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.29 no.1B
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• pp.117-124
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• 2004

With MPEG-4 3D mesh coding(3DMC), the problem of the need of a wide bandwidth can be solved to store and transmit 3D information because of its high compression rate. And to realize the 3D information service with broadcasting or internet, one needs to transmit not only the 3D contents but also the 3D player. Therefore, in this paper we implement a 3D player based on MPEG-4 using a java language. A well-known java language employed in this paper provides the player with a wider range of applications, for example, when the O/S or the platform are different, due to its properties of scalability and universality. The implemented player which has functions (translation, rotation, etc) that can manipulate contents decodes the 3D contents and displays them. In addition, the player has a network function that receives a 3D content from the server. This paper explains the architecture and characteristics of the player and shows its simulation results.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.16 no.1
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• pp.119-126
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• 2012

H.264/AVC can use three transforms depending on types of residual data which are to be coded. H.264/AVC always executes $4{\times}4$ DCT transform. In $16{\times}16$ intra mode only, $4{\times}4$ Hadamard transform for luma DC coefficients and $2{\times}2$ Hadamard transform for chroma DC coefficients are performed additionally. Quantization is carried out to achieve further data compression after transform coding is completed. In this paper, the hardware implementation for DCT transform, Hadamard transform and quantization is studied. Especially, the proposed architecture adopting the pipeline technique can output a quantized result per clock cycle after 33-clock cycle latency. The proposed architecture is coded in Verilog-HDL and synthesized using Xilinx 7.1i ISE tool. The operating frequency is 106MHz at SPARTAN3S-1000. The designed IP can process maximum 33-frame at $1920{\times}1080$ HD resolution.