• Korean Journal of Digital Imaging in Medicine
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• v.4 no.1
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• pp.166-180
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• 1998

$\cdot$ 영상 압축은 영상의 통계학적 분포, 반복성을 이용하여 빈도가 높은 데이터는 적은 수의 bits를, 빈도가 낮은 데이터에는 보다 많은 수의 bits를 할당하여 전체 영상을 나타내는 bits 수를 줄이는 것임. $\cdot$ 영상 압축은 크게 Lossy Coding, Lossless Coding으로 나뉘며, Lossy coding은 DCT, 양자화기, VLC Codes를 쓰며 압축 율은 높으나 원래의 영상을 정확히 복원하지 못함. $\cdot$ 영상 압축에 대한 국제 규격 협회는 JPEG, MPEG I, MPEG II, MPEG IV, H.261, H.263 등이 있으나 본 seminar에서는 JPEG 규격만 논함. $\cdot$ 의학 영상은 Resolution이 크고 study 단위로 관리되기 때문에 영상 데이터량이 많으나 진단의 목적으로 쓰이기 때문에 주로 lossless 압축을 쓰게 되나 압축율이 낮음.(3:1 이하). 최근에는 Fractal, Wavelet Coding을 통한 압축율을 증가 시키는 Image Compression Algorithms이 활용됨. $\cdot$ MPEG은 동영상의 압축 표준안이며, 동영상은 한frame 당 25개 이상의 정지 화상으로 이루어지기 때문에 JPEG 규격에서 사용되었던 기법이 그대로 활용되며 영상과 영상간, 또는 frame과 frame 간의 여상의 변화, 움직임을 Vector로 coding하는 interframe Coding 기법을 활용하나 설명하기에는 광범위한 topic이므로 본 seminar에서는 생략함.

• Proceedings of the Korean Institute of Communication Sciences Conference
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• 1992.06a
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• pp.461-464
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• 1992

• Proceedings of the Korean Institute of Communication Sciences Conference
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• 1996.06a
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• pp.144-147
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• 1996

• Proceedings of the Korean Institute of Communication Sciences Conference
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• 1996.06a
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• pp.452-456
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• 1996

• The Journal of Korean Institute of Communications and Information Sciences
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• v.23 no.6
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• pp.1526-1537
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• 1998

The split-screen function on the multipoint control unit(MCU) which is usually using processing method based on pixel domain has many problems for manipulating the video signal in real-time. Although the researches and the developements to cope ith such problems are processing, these have too complex architecture to implement and are limited to method for H.261 video signal. In this paper, we propose a new mechanism for split-screen that can actually apply to ISO/IEC MPEG video standard. The new method that is proposed in this paper do the processes in complete compression domain, thus it is suitable for the application of real-time multipoint multimedia communication service. By simple interpreting and manipulating the MPEG video element stream, the split-screen functional module can be implemented easily and the result of the procedures does not accompany image degradation at all. Finally, the complexity of implementation, the aspect for processing delay and the loss of image quality as compared to that resulting in the case of applying the previous split-screen method has been investigated. And it is confirmed that the proposed mechanism has a significant advantage as a split-screen method.

• Journal of Korea Multimedia Society
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• v.5 no.4
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• pp.393-398
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• 2002

The conventional bit allocation scheme for MPEG-1 audio encoding searches the subband with minimum MNR(mask-to-noise ratio) repetitively until its operation is completed, which occupies most of its total computational complexity. In this paper, as a computationally efficient approximation of it, we propose a new bit allocation scheme with a simple subband search and compare it with the existing schemes[1][2] in terms of the computational complexity and sound quality. For the performance comparison, we used the pop music signal contained in SQAM(sound quality assess material) CD from EBU. Simulation results show that the computational complexity of the proposed method is about 42% of that of the existing one in [1] and the sound quality difference in terms of MNR between the two schemes is within the 0.2 ㏈, for the case of using the layer II at the bit rate of 128 kbps.

• Proceedings of the Korea Contents Association Conference
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• 2005.05a
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• pp.165-171
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• 2005

we can define the procedure of Authoring that it makes area cord and the reproduction prevent menu programmed into MPEG II video stream , Audio which is AC-3 audio stream and subtitle under its own category. And it makes process an attribute, an order and an operation, gives the last disk image (DVD). There are various types of Authoring tools in the market so that authoring tools can enable, encourage, and assist users ('authors') in the selection of tools that produce simple title and video production and editing suites. In this paper, we will compare and analyze authoring process in which image and sound are captured into DVD creation with IEEE 1394port with regard to Window system using generally with Desktop PC and the Macintosh of the PC on the system of Windows and OSX.

• The Journal of the Korea Contents Association
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• v.5 no.5
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• pp.145-151
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• 2005

We can define the procedure of Authoring that it makes area cord and the reproduction prevent menu programmed into MPEG II video stream , Audio which is AC-3 audio stream and subtitle under its own category. And it makes process an attribute, an order and an operation, gives the last disk image, Which is DVD(digital versatile disc). There are various process of Authoring tools in the market so that authoring tools can enable, encourage, and assist users ('authors') in the selection of tools that produce simple title, video production and editing suites. In this paper, we will compare and analyze authoring process in which image and sound are authorized into DVD with IEEE 1394port between Window system using generally with Desktop PC and the Macintosh that is based on OSX.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.40 no.6
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• pp.106-113
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• 2003

The modified discrete cosine transform (MDCT) and inverse MDCT (IMDCT) are employed in subband/transform coding schemes as the analysis/synthesis filter bank based on time domain aliasing cancellation (TDAC). And the MDCT and IMDCT are the most computational intensive operations in layer III of the MPEG audio coding standard. In this paper, we propose a new efficient algorithm for the MDCT/IMDCT computation in various audio coding systems. It is based on the MDCT/IMDCT computation algorithm using the discrete cosine transforms (DCTs), and It employs two discrete cosine transform of type II (DCT-II) to compute the MDCT/IMDCT In addition, it takes advantage of ability in calculating the MDCT/IMDCT computation, where the length of a data block Is divisible by 4. The Proposed algorithm in this paper requires less calculation complexity than the existing method does. Also, it can be implemented by the parallel structure, therefore its structure is particularly suitable for VLSI realization

• Journal of Broadcast Engineering
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• v.2 no.2
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• pp.125-135
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• 1997

This paper is concerned with realistic mainpulation of content in video sequences. Manipulation of content in video sequences is one of the content-based functionalities for MPEG-4 Visual standard. We present an approach to synthesizing video sequences by using the intermediate outputs of three-dimensional (3D) motion and depth analysis. For concreteness, we focus on video showing 3D motion of an observer relative to a scene containing planar runways (or roads). We first present a simple runway (or road) model. Then, we describe a method of identifying the runway (or road) boundary in the image using the Point of Heading Direction (PHD) which is defined as the image of, the ray along which a camera moves. The 3D motion of the camera is obtained from one of the existing 3D analysis methods. Then, a video sequence containing a runway is manipulated by (i) coloring the scene part above a vanishing line, say blue, to show sky, (ii) filling in the occluded scene parts, and (iii) overlaying the identified runway edges and placing yellow disks in them, simulating lights. Experimental results for a real video sequence are presented.