• Proceedings of the Korean Information Science Society Conference
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• 2005.11b
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• pp.856-858
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• 2005

본 논문에서는 비디오 영상 및 이미지 시퀀스의 특징점 추적을 통해 얻은 2D 좌표를 분해기법을 사용하여 특징점에 대응되는 3D 좌표를 추정하는 방법을 제안한다. 3D 좌표를 복원함과 동시에 카메라의 위치와 방향을 계산하였다. 분해 기법에는 직교분해기법, 스케일된 직교분해기법, 근접 원근분해기법이 있다. 본 논문에서는 형상과 카메라 움직임을 계산하는 개선된 직교 분해 기법을 제안한다. 제안된 방법을 실 영상에 대해 실험한 결과 구조 및 카메라 파라메터 추정의 정확성이 개선되었다.

• 한국HCI학회:학술대회논문집
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• 2006.02a
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• pp.486-492
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• 2006

본 논문에서는 비디오에서의 특징점 추적을 통해 얻은 2D 좌표를 이용한 3D 구조를 추정하는 방법과 네 점 이상의 공통점을 이용한 융합 방법을 제안한다. 영상의 각 프레임에서 공통되는 특징점을 이용하여 형상을 추정한다. 영상의 각 프레임에 대한 특징점의 추적은 Lucas-Kanade 방법을 사용하였다. 3D 좌표 추정 방법으로 개선된 직교분해기법을 사용하였다. 개선된 직교분해기법에서는 3D 좌표를 복원함과 동시에 카메라의 위치와 방향을 계산할 수 있다. 복원된 부분 데이터들은 전체를 이루는 일부분이므로, 융합을 통해 완성된 모습을 만들 수 있다. 복원된 부분 데이터들의 서로 다른 좌표계를 기준 좌표계로 변환함으로써 융합할 수 있다. 융합은 카메라의 모션에 해당하는 카메라의 위치와 방향에 의존된다. 융합 과정은 모두 선형으로 평균 0.5초 이하의 수행 속도를 보이며 융합의 오차는 평균 0.1cm 이하의 오차를 보였다.

• Journal of Korea Multimedia Society
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• v.10 no.3
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• pp.303-315
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• 2007

This paper proposes a 3D structure recovery and registration method that uses four or more common points. For each frame of a given video, a partial structure is recovered using tracked points. The 3D coordinates, camera positions and camera directions are computed at once by our improved scaled orthographic factorization method. The partially recovered point sets are parts of a whole model. A registration of point sets makes the complete shape. The recovered subsets are integrated by transforming each coordinate system of the local point subset into a common basis coordinate system. The process of shape recovery and integration is performed uniformly and linearly without any nonlinear iterative process and without loss of accuracy. The execution time for the integration is significantly reduced relative to the conventional ICP method. Due to the fast recovery and registration framework, our shape recovery scheme is applicable to various interactive video applications. The processing time per frame is under 0.01 seconds in most cases and the integration error is under 0.1mm on average.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.27 no.8A
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• pp.829-835
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• 2002

When finite length image signal is decomposed into M-band synthesized using M-band orthogonal wavelet transform, the boundary signal of image are not reconstructed perfectly. for boundary signals to be reconstructed perfectly, different type filter bank or technique is applied to them when the dimension of analysed is proposed. It can be designed using the singular value decomposition of boundary perfect reconstruction matrix which is obtained from paraunitary matrix which is obtained from paraunitary matrix. And it is also discussed to design the boundary filter bank for improving the coding performance when it is applied to subband coder. The proposed boundary filter bank shows 7% gains in PSNR compared with reflected method.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.23 no.4
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• pp.1072-1086
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• 1998

Transform, subband, and wavelet transform decompositions are powerful linear transformation tools in image coding because of their decorrelating effects on image pixels, the concentration of energy in a few coefficients, their multirat/multiresolution framework, and their frequency splitting, which allows for efficient coding matched to the statistics of each frequency band and to the characteristics of the human visulal system. Thus, a growingbody of research has bee performed to extend these tools in various kinds of modified formations. Hence, in this paper, an overall survey to achieve a general view on these transformation tools have been attempted. Starting from basic tools such as orthogonal transforms, lapped transforms, QMF(quadrature mirror filter) subband filter banks, and wavelet transforms, their hierarchical extensions, vector extensions, and linear time-varying extensions are investugated in detail.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.4 no.5
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• pp.997-1003
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• 2000

When finite length signal is the input of QMF banks which are composed of the M-band orthogonal wavelet filter, the boundaries of reconstructed signal are not reconstructed perfectly. For boundary signals to be reconstructed perfectly, different type filters or methods are applied to them. In this paper, the design method of boundary filters which can be reconstructed the boundary signal perfectly was proposed, in case the dimension of M-band decomposed signal is the same as that of input signal. The boundary filters were designed using the perfect reconstruction condition of paraunitary matrix. In an application of subband coding of still image, the proposed boundary filters achieve better PSNR about 5% in reconstructed image than reflected method at the same bit rate.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.34 no.12A
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• pp.933-940
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• 2009

This paper proposes a robust detection scheme for quasi-orthogonal space-time block code over time-selective fading channels. The proposed detector performs interference cancellation and decision feedback equalization to remove the inter-antenna interference and inter-symbol interference when the channel varies from symbol to symbol. Cholesky factorization is used on the channel Gram matrix after performing interference cancellation to obtain feed forward equalizer and feedback equalizer. It is shown by simulations that the proposed detection scheme outperforms the conventional detection schemes and the exiting detection schemes to time-selectivity.