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윤곽선 정보의 전송이 불필요한 분할기반 영상 부호화 방법
최재각(Jae Gark Choi),강현수(Hyun-Soo Kang),고창림(Chang-Rim Koh),권오준(Oh-Jun Kwon),이종극(Jong-Keuk Lee) 한국정보과학회 2005 정보과학회논문지 : 시스템 및 이론 Vol.32 No.5·6
본 논문은 윤곽선 정보의 전송이 불필요한 새로운 분할기반 영상 부호화 방법을 제안한다. 분할기반 영상 부호화에서 전송해야할 전체 정보 중 윤곽선 정보가 다른 정보에 비해 상대적으로 많은 부분을 차지하기 때문에 윤곽선 정보가 전체 전송정보의 병목현상으로 작용한다. 제안된 방법은 현재 프레임을 분할하는 대신, 복호화된 이전 프레임을 분할함으로써, 복호기로 분할된 영역에 대한 윤곽선 정보를 전송하지 않아도 되는 장점이 있다. 따라서 윤곽선 정보를 전송하지 않음으로써 여분의 비트를 오차신호와 같은 다른 정보의 전송에 할당하여 부호화 화질을 개선할 수 있다. 실험결과에 나타난 것처럼, 전송 비트율이 제한된 초저전송율 부호화에서 급격한 움직임으로 데이타 발생이 크게 증가할 경우 기존 블록기반 부호화에서는 PSNR이 20㏈ 부근까지 떨어지지만 제안된 방법은 급격한 PSNR 저하없이 우수한 재생화질을 나타내었다. A new segmentation-based image coding method which no needs transmission of contour data is proposed. The shape information acts as bottleneck in the segmentation-based video coding because it has much portion of transmission data. The proposed method segments a previous decoded frame, instead of a current frame. As a result, there is no need for transmission of contour information to a decoder. Therefore, the saved bits can be assigned to encode other information such as error signals. As shown in experiment results, if data rate is very highly increased due to abrupt motion under very low bit rate coding having limited transmission bits, PSNR of conventional block-based method go down about 20dB, while the proposed method shows a good reconstruction quality without rapid PSNR drop.
비보정된 스테레오 영상의 시점 합성을 위한 문턱값 설정방법
최재각 ( Jae Gark Choi ),남재열 ( Jae Yeal Nam ),구본호 ( Bon Ho Ku ),김이국 ( Iee Kook Kim ) 한국화상학회 2002 한국화상학회지 Vol.8 No.2
This paper proposes a threshold selection method for view synthesis of uncalibrated stereo sequence. Seiz`s view synthesis method first calculates corner values using comer detector, and then decide comer point with comparison of fixed threshold. However this paper decides automatically threshold value using statistic of image. As shown in simulation results, the proposed method finds exact correspondence of comer point and second obtains excellent view synthesis results form stable implementation such as exact computation of fundamental matrix.
이진 원형 패턴을 이용한 RST 공격에 강인한 영상 워터마킹 방법
최재각 ( Jae Gark Choi ),김진일 ( Jin Il Kim ) 한국화상학회 2007 한국화상학회지 Vol.13 No.2
This paper proposes a new image normalization-based watermarking scheme which has a robustness against RST(Rotation, Scaling, Translation) attacks by using binary circular pattern. Conventional image normalization-based watermarking methods transform an image as normalized image of standard form by calculating centroids and moments, and then by inserting watermark. However RST attacks causes the boundary effects which are appeared as cropping of image boundary. Therefore watermark can not be detected because normalization parameters are changed. To solve this problem, this paper normalizes the images using only internal area of image. To extract this internal area, we proposed binary circular pattern which is invariant under any geometric attacks. Normalization parameters are calculated using this circular pattern. Experimental results show that the proposed method is more robust to RST attack than conventional method.
모델 적합성 판정을 이용한 전역 움직임 보상 유무 판정 방법
최재각 ( Jae Gark Choi ),고창림 ( Chang Rim Koh ),신현순 ( Hyun Soon Shin ) 한국화상학회 2007 한국화상학회지 Vol.13 No.4
This paper addresses a global motion compensation on/off decision method which is exploited in video coding areas. The conventional video coding using global motion compensation always compensates the global motion, assuming that the global motion between consecutive two frames of image sequences always exists. However, in the case that the global motion dose not occur in video sequences, global motion compensation causes a degradation of coding efficiency and requires unnecessary computation loads. Therefore the decision on whether the global motion compensation be performed should be made in some way. In this paper, a global motion on/off decision mechanism is performed by estimating global motion and then by using a model adequate test. Simulation results shows that coding efficiency is increased by applying the global motion compensation on/off decision method.
최재각(Choi Jae-Gark),이문노(Lee Moon-Noh),이종국(Lee Jong-Keuk) 동의대학교 정보통신연구소 2004 정보통신연구지 Vol.5 No.-
This paper presents a new morphological spatio-temporal segmentation algorithm. The algorithm incorporates intensity and motion information simultaneously, and uses morphological tools such as morphological filters and watershed algorithm. The procedure toward complete segmentation consists of three steps: joint marker extraction, boundary decision, and motion-based region fusion. By incorporating spatial and temporal information simultaneously, we can obtain visually meaningful segmentation results. Simulation results demonstrates the efficiency of the proposed method.
최재각 ( Jae Gark Choi ) 한국화상학회 2010 한국화상학회지 Vol.16 No.1
This paper addresses a new extraction method of moving objects combining depth information. The conventional methods extract moving objects by using the difference of successive frames. Hence, it shows inaccurate and irregular object boundaries. To solve this problem, the proposed method corrects the segmentation results using depth information. First, the segmentation results are obtained by the frame difference algorithm. Next the results are corrected by using depth information. The watershed algorithm is used for the correction of the segmentation results. As shown in experimental results, the proposed algorithm show more accurate and smooth object boundaries