• 대한전자공학회:학술대회논문집
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• 대한전자공학회 1999년도 추계종합학술대회 논문집
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• pp.360-363
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• 1999

Video data compression is a major key technology in the field of multimedia applications. Variable-length coding is the most popular data compression technique which has been used in many data compression standards, such as JPEG, MPEG and image data compression standards, etc. In this paper, we present memory efficient VLC decoder architecture for MPEG-2 application which can achieve small memory space and higher throughput. To reduce the memory size, we propose a new grouping, remainder generation method and merged lookup table (LUT) for variable length decoders (VLD's). In the MPEG-2, the discrete cosine transform (DCT) coefficient table zero and one are mapped onto one memory whose space requirement has been minimized by using efficient memory mapping strategy The proposed memory size is only 256 words in spite of mapping two DCT coefficient tables.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2003년도 하계종합학술대회 논문집 Ⅳ
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• pp.1787-1790
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• 2003

In this paper. we proposed a hardware(H/W) structure which can compress the video and embed the watermark in real time operation and implemented it into a FPGA platform using VHDL(VHSIC Hardware Description Language). All the image processing element to process both compression and reconstruction in a FPGA were considered each of them was mapped into H/W with the efficient structure for FPGA. The global operations of the designed H/W consists of the image compression with the watermarking and the reconstruction, and the watermarking operation is concurrently operated with the image compression. The implemented H/W used the 59％(12943) LAB(Logic Array Block) and 9％(28352) ESB(Embedded System Block) in the APEX20KC EP20K600CB652-7 FPGA chip of ALTERA, and stably operated in the 70㎒ clock frequency over. So we verified the real time operation, 60 fields/sec(30 frames/sec).

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2003년도 하계종합학술대회 논문집 Ⅳ
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• pp.1875-1878
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• 2003

This paper Proposes a wavelet-based video compression method to improve compressed images using modification of wavelet coefficients. In conventional wavelet-based compression methods, bigger coefficients are transmitted early according to the significance of the coefficients. In this reason, when some coefficients which have more significance but are not bigger are not transmitted, image degradation occurs. The Proposed method considered two human visual characteristics. First, human eyes are more sensitive to the change of middle frequency which represents abrupt change of brightness than that of high frequency which expresses fine region. Second, human eyes are more dull to color component than luminance respectively. By adjusting the coefficients of wavelet transformed signals and allocating more bits for compression to the luminance signal, higher compression could be achieved.

• 대한전자공학회논문지SP
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• 제46권3호
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• pp.75-88
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• 2009

본 논문에서는 실시간 멀티미디어 스트림 서비스에서 발생하는 비디오 품질 저하 요인에 따른 비디오 품질 측정 방법을 제안한다. 비디오 품질 저하에는 대표적으로 비디오 압축과 네트워크의 상태에 의해 발생한다. 본 논문에서는 비디오 압축에 의하여 생기는 화질 저하를 측정하기 위하여 공간 도메인에서 블록킹 왜곡에 대한 정도를 측정하는 방법을 제안한다. 제안하는 블록 경계 강도는 $8{\times}8$ 블록 경계에서 픽셀간의 변화와 경계를 제외한 주변영역에서 픽셀 사이의 변화에 대한 비율로 나타내었다. 반면, 움직임이 부자연스러운 동영상은 지터 및 지연 요소와 같은 네트워크 전송능력의 악화로 인해 비디오 품질 저하가 나타난다. 본 논문에서 제안하는 시간적 저키니스는 연속된 프레임의 대응되는 픽셀간의 밝기 값 차이에 대한 평균과 현재 프레임과 이전 프레임의 재생시간 간격의 평균 및 분산을 이용하는 방법을 제안하였다. 또한, 본 논문에서는 비디오 압축에 의한 품질 측정 방법인 블록 경계 강도와 네트워크에 의한 품질 측정 방법인 시간적 저키니스를 통합하여 비디오의 종합적 품질을 평가하는 Perceptual Video Quality Metric (PVQM)을 제안한다. 제안한 알고리즘의 성능을 평가하기 위하여, 사람이 직접 비디오 품질을 평가하는 Difference of Mean Opinion Score (DMOS)와 제안한 알고리즘을 비교 평가하였다. 그 결과 제안한 PVQM의 결과와 인간 시각에 의하여 평가된 DMOS가 근사함을 확인하였다.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1997년도 한국자동제어학술회의논문집; 한국전력공사 서울연수원; 17-18 Oct. 1997
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• pp.1383-1386
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• 1997

Discrete cosine transform(DCT) is the most popular block transform coding in lossy mode. DCT is close to statistically optimal transform-the Karhunen Loeve transform. In this paper, a module for DCT encoder is made with TMS320C80 based on JPEG and MPEG, which are intermational standards for image compression. the DCT encoder consists of three parts-a transformer, a vector quantizer and an entropy encoder.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2000년도 추계종합학술대회 논문집(4)
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• pp.183-186
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• 2000

Motion estimation technique has been used to increase video compression rates in motion video applications. One of the important algorithms to implement the motion estimation technique is search algorithm. Among many search algorithms, the H.263 adopted the Nearest Neighbors algorithm for fast search. In this paper, motion estimation block for the Nearest Neighbors algorithm is designed on FPGA and coded using VHDL and simulated under the Xilinx foundation environments. In the experiment results, we verified that the algorithm was properly designed and performed on the Xilinx FPGA(XCV300Q240)

• 한국정보통신학회:학술대회논문집
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• 한국해양정보통신학회 2003년도 춘계종합학술대회
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• pp.175-178
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• 2003

본 논문에서 제안된 시스템에서는 실시간 MPEG-2 압축과 효과적인 색인 알고리듬을 사용한 기억장소로부터 복구된 비디오를 사용한다. 시스템은 넓은 군사범위, 인접한 부대에서 확산된 장소, 그리고 장거리 이미지 전송을 감시한다.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2003년도 신호처리소사이어티 추계학술대회 논문집
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• pp.11-14
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• 2003

In block-based lossy video compression, severe quantization causes discontinuities along block boundaries so that annoying blocking artifacts are visible in decoded video imases. These blocking artifacts significantly decrease the subjective image quality. In order to reduce the blocking artifacts in decoded images, many algorithms have been proposed However studies on so called, corner outliers, have been very limited. Corner outliers make image edges look disconnected from those of neighboring blocks at cross block boundary. In order to solve this problem, we propose a corner outlier detection and compensation algorithm as post-processing in spatial domain The experiment results show that the proposed method provides much improved subjective image quality.

• 전자공학회논문지C
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• 제35C권5호
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• pp.25-32
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• 1998

In this paper, SA (shape adaptive)-DCT is implemented using a datapath with 4 MACs (multiplication & accumulator). DCT is a well-known bottleneck of real-time video compression using MPEG-like schemes. High-speed pipelined MACs presented here implement real-time DCT. A datapath in this paper executes DCT/IDCT algorithms for QCIF 15fps(frame per second), maximum rate of VLBV(very low bitrte video) in MPEG-4. A 32bit accumulator in a MAC prevents distortion caused by fixed-point process. It can be applied to various operations such as ME (motion estimation) and MC(motion compensation) with a absolutor and a halfer.

• 한국방송∙미디어공학회:학술대회논문집
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• 한국방송공학회 1997년도 학술대회
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• pp.151-154
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• 1997

In this paper, we propose a new watermarking algorithm for copyright protection of video data. The proposed algorithm inserts a watermark directly on the MPEG-2 bitstream. Since more and more video data are stored and transmitted in a compressed form, it is desirable to insert a watermark on the compressed bit stream to avoid the expensive full-decoding and re-encoding process. Embedding a watermark in the compressed domain, we can also avoid the effect of the compression error which may erase the watermark.