• Proceedings of the Korean Society of Broadcast Engineers Conference
• /
• 2012.11a
• /
• pp.184-185
• /
• 2012

H.264/AVC 는 다중 참조영상을 사용하여 움직임 예측/보상을 수행함으로써 보다 높은 부호화 효율을 얻을 수 있지만 다중 참조영상에 대한 움직임 예측으로 인하여 부호화 복잡도 증가를 야기한다. 본 논문에서는 공간적 상관성을 이용하여 참조영상 수를 제한함으로써 부호화기의 복잡도를 줄이는 고속 참조영상 결정 기법을 제안한다. 즉, 주변 블록의 부호화 정보와 현재 부호화하는 매크로블록의 $16{\times}16$ 화면간 예측 결과를 적응적으로 이용하여 참조영상 후보의 수를 줄인다. 모의실험에서 제안한 알고리즘은 JM17.2 에 비해 0.67%의 평균 비트율 증가의 미미한 부호화 효율 감소에 평균 47% 정도의 부호화 시간을 감소하였으며, 기존의 고속 기법보다 우수한 성능을 보임을 확인하였다.

• Proceedings of the Korean Information Science Society Conference
• /
• 2007.10d
• /
• pp.564-568
• /
• 2007

H.264/AVC는 최신의 국제 비디오 압축 표준으로 가변블록크기 지원, 다중 참조 프레임 움직임 보상 등의 기법으로 이전의 압축 표준인 MPEG-4, H.263등에 비해 비슷한 화질에서 비트율을 거의 50%정도 줄였다. 이러한 기법들로 압축 효율성이 높아진 반면, 계산 복잡도는 증가하게 되었다. 따라서 본 논문에서는 움직임 벡터 예측인 MVP를 이용하여 시간적 상관성을 고려하고 프레임 내의 주위 매크로블록 모드정보에 가중치를 부여하여 부호화를 매크로블록의 최종 모드를 빠르게 선택하는 기법을 제안한다. 실험에서 JM10.2의 모드 선택기법과 비교한 결과, 평균 85%이상 선택한 모드가 동일함을 보여주었다.

• Proceedings of the Korean Information Science Society Conference
• /
• 2004.04a
• /
• pp.445-447
• /
• 2004

본 논문에서는 H.263과 같은 MC-DCT방법을 사용하는 코덱에서 IDCT와 MC(Motion Compensation, 움직임보상)방법을 부분적으로 수정하여 제한된 비율의 축소영상을 디코딩 과정에서 직접 얻을 수 있는 방법을 제안한다. 제안한 방법에서는 8$\times$8 DCT 블록에 대하여 약간의 연산을 가하여 k$\times$k IDCT를 수행하고, 시간적 중복성을 제거하는 과정에서 근사적 움직임벡터를 이용한 2k$\times$2k MC 를 수행하였다. 기존의 코덱을 사용하고 후처리로 축소를 하는 경우와 비교하였을 때에 추가적인 오버헤드가 매우 경미하고 디코딩 과정이 많이 축소되어 계산효율에 있어서 대략 32%의 개선된 실험결과를 얻었고, 화질저하 현상이 개선됨을 실험적으로 보였다.

• Proceedings of the Korea Information Processing Society Conference
• /
• 2000.04a
• /
• pp.1148-1152
• /
• 2000

본 논문에서는 기존의 H.26X 부호화 시의 속도 저하의 원인인 움직임 추정의 높은 복잡도를 개선하여 소프트웨어만으로 실시간 부호화를 하는 방법을 모색하고자 한다. 논문에서는 스탠포드 대학에서 작성한 소프트웨어 부호기를 분석하여 속도를 높이기 위한 해결 방법으로 두 가지 방법으로 접근하였다. 첫째로 부호기의 속도 저하의 원인인 움직임 추정의 시간을 줄이기 위하여 현재 많이 사용되고 있는 4단계 탐색 알고리즘을 개선한 새로운 알고리즘을 제안하였다. 둘째로 현재 작성된 코드를 인텔사에서 제공하는 ${MMX^{TM}}$ 명령어를 사용, 병렬처리 하여 속도 향상을 꾀하였다.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• 2016.10a
• /
• pp.872-875
• /
• 2016

본 연구에서는 무구속적으로 사용자의 활동상태를 모니터링하고 이를 기반으로 산만도를 추정하기 위한 연구를 수행하였다. 사용자의 활동상태 모니터링을 위해서는 키넥트 센서를 활용하여 머리에서의 관절정보와 어깨관절정보를 검출하고, 각 검출지점의 시간당 좌표변화를 인덱스화하여 움직임 변화정도를 측정하였다. 이러한 움직임정보로부터 산만도의 추정을 위하여 움직임의 빈도와 움직임의 강도를 분석하고 이로부터 산만도를 추정하기위한 인덱스를 개발하였다. 실제 사용자의 활동상태로부터 추출된 움직임정보 및 산만도 추정인덱스의 모니터링을 위하여 PC기반의 모니터링 및 스마트폰기반의 어플리케이션을 구현하였다. 구현된 시스템의 성능평가를 위하여 키넥트를 이용한 산만도 추정 어플리케이션과 동시에 비디오 계측을 통해 움직임의 정도에 따른 산만도 추정식의 결과를 비교분석한 결과 개발된 산만도 추정시스템과 비디오분석결과의 상관관계가 높음을 실험으로 확인하였다.

• The KIPS Transactions:PartB
• /
• v.11B no.2
• /
• pp.177-186
• /
• 2004

It is a weak point of the motion estimation technique for video compression that the predicted video encoding algorithm requires higher-order computational complexity. To reduce the computational complexity of encoding algorithms, researchers introduced techniques such as 3D-WT that don't require motion prediction. One of the weakest points of previous 3D-WT studies is that they require too much memory for encoding and too long delay for decoding. In this paper, we propose a technique called `FS (Fast playable and Scalable) 3D-WT' This technique uses a modified Haar wavelet transform algorithm and employs improved encoding algorithm for lower memory and shorter delay requirement. We have executed some tests to compare performance of FS 3D-WT and 3D-V. FS 3D-WT has exhibited the same high compression rate and the same short processing delay as 3D-V has.

• Journal of the Institute of Electronics Engineers of Korea SP
• /
• v.43 no.4 s.310
• /
• pp.74-86
• /
• 2006

This paper proposes a robust and computationally efficient algorithm for automatic video object segmentation. For implementing the spatio-temporal segmentation, which aims for efficient combination of the motion segmentation and the color segmentation, an SOM-based hierarchical clustering method in which the segmentation process is regarded as clustering of feature vectors is employed. As results, problems of high computational complexity which required for obtaining exact segmentation results in conventional video object segmentation methods, and the performance degradation due to noise are significantly reduced. A measure of motion vector reliability which employs MRF-based MAP estimation scheme has been introduced to minimize the influence from the motion estimation error. In addition, a noise elimination scheme based on the motion reliability histogram and a clustering validity index for automatically identifying the number of objects in the scene have been applied. A cross projection method for effective object tracking and a dynamic memory to maintain temporal coherency have been introduced as well. A set of experiments has been conducted over several video sequences to evaluate the proposed algorithm, and the efficiency in terms of computational complexity, robustness from noise, and higher segmentation accuracy of the proposed algorithm have been proved.

• Journal of Korean Ophthalmic Optics Society
• /
• v.12 no.1
• /
• pp.1-7
• /
• 2007

To investigate the momentary movement pattern of soft contact lens(SCL) depending on wearing time, eight types of soft contact lenses were worn by 10 normal subjects and the momentary movements of SCLs were estimated using by high speed camera(FASTCAM ultima 1024). When the momentary movements of SCLs in the cornea between blinkings were compared after 15 min wearing, the vertical movements of all eight SCLs were about 2 times larger than the horizontal movement but the extent of these movement difference was a function of kinds of SCLs. The momentary moving distance of SCL varied from the kinds of SCLs, which A and B lens, daily wear lens, moved significantly larger distance compared with other SCLs. The momentary movements between blinkings decreased significantly after 8hr wear of SCLs. The extents were different when SCLs were compared with each other, which the reduction range of horizontal and vertical movement was 24.6~60.0% and 20.4~94.3%, respectively. The A, B and C lenses which had relatively higher water content showed the larger movement reduction after SCL wear. This results suggest that wearing SCL for some hours decreases the movement of SCl, which can induce the change of tear flow.

• Journal of Broadcast Engineering
• /
• v.18 no.2
• /
• pp.178-184
• /
• 2013

In this paper, we propose an efficient parallelization technique of PU-level motion estimation (ME) in the next generation video coding standard, high efficiency video coding (HEVC) to reduce the time complexity of video encoding. It is difficult to encode video in real-time because ME has significant complexity (i.e., 80 percent at the encoder). In order to solve this problem, various techniques have been studied, and among them is the parallelization, which is carefully concerned in algorithm-level ME design. In this regard, merge estimation method using merge estimation region (MER) that enables ME to be designed in parallel has been proposed; but, parallel ME based on MER has still unconsidered problems to be implemented ideally in HEVC test model (HM). Therefore, we propose two strategies to implement stable parallel ME using MER in HM. Through experimental results, the excellence of our proposed methods is shown; the encoding time using the proposed method is reduced by 25.64 percent on average of that of HM which uses sequential ME.

• The Journal of Korean society of community based occupational therapy
• /
• v.4 no.2
• /
• pp.11-22
• /
• 2014

Objective : The purpose of this study is to investigate the effect of mental practice with task activities through upper limbs movement speed and accuracy in ideomotor apraxia patient. Methods : As a single subject research design with multiple baseline across individuals, the patients were two ideomotor apraxia patients, employed in this study. The employed program included receiving mental practice and task activities, measuring change of the total performance times, time to put down the last cups and amount of water in cups for 4 weeks, including baseline and intervention periods. The subject were measured by Ideomotor apraxia test and MFT were analyzed. The analyses were performed using visually and two-standard deviation band method. Results : All subjects were a reduction in symptoms of apraxia, but noticeable change in upper limbs function was not there. Total time of performance from 376.67 to 355.24 seconds, 391.33 seconds to 434.60 seconds, reduced. Put down the cup of performance time from 15.67 to 13.30 seconds, 20.80 seconds to 10.73 seconds, reduced. The amount of water transferred from 52.38ml to 49.70ml, 50.89ml to 50.09ml, all results were closer to 50ml. Conclusion : As a result of this study, mental practice with task activities can be an effective method to ideomotor apraxia patients. This study would serve a fundamental data on ideomotor apraxia patients to the further studies.