• Journal of the Korea Society of Computer and Information
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• v.11 no.6 s.44
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• pp.269-277
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• 2006

We propose a new expert system for recovering the broken fragments of relics into an original form using computer graphics and image processing. This paper presents a system with an application to tombstones objects of flat plane with letters carved in for assembling the fragments by placing their respective fragments in the right position. The matching process contains three sub-processes: aligning the front and letters of an object, identifying the matching directions, and determining the detailed matching positions. We apply least squares fitting, vector inner product, and geometric and RGB errors to the matching process. It turned out that 2-D translations via fragments-alignment enable us to save the computational load significantly. Based on experimental results from the damaged cultural fragments, the performance of the proposed method is illustrated.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.28 no.4C
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• pp.424-432
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• 2003

In this paper, an effective method of stereo image reconstruction through the regularized adaptive disparity estimation is proposed. Althougth the conventional adaptive disparity estimation method can sharply improve the PSNR of a reconstructed stereo image, but some problems of overlapping between the matching windows and disallocation of the matching windows can be occurred, because the matching window size changes adaptively in accordance with the magnitude of feature values. Accordingly, in thia paper, a new regularized adaptive disparity estimation technique is proposed. That is, by regularizing the estimated disparity vector with the neughboring disparity vectors, problems of the conventional adaptive disparity estimated scheme might be solved, and also the predicted stereo image can be more effectively reconstructed. From some experiments using the CCETT'S stereo image pairs of 'Man' and 'Claude', it is analyzed that the proposed disparity estimation scheme can improve PSNRs of the reconstructed images to 10.89dB, 6.13dB for 'Man' and 1.41dB, 0.81dB for 'Claude' by comparing with those of the conventional pixel-based and adaptive estimation method, respectively.

• Proceedings of the Korea Multimedia Society Conference
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• 2003.11a
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• pp.294-297
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• 2003

최근 3차원 영상의 압축 방법에 대한 연구가 여러 분야에서 활발히 이루어지고 있으며, 특히 MPEG에서는 이와 관련하여 Exploration Experiment를 통하여 효율적인 기법을 연구하고 있다. 본 논문에서는 EE3를 위하여 스테레오 비디오 압축을 위한 효율적인 블록기반 시차예측 기법을 제안한다. 제안된 알고리즘은 스테레오 영상의 특성 중 주변 블록의 시차 벡터가 유사하다는 점을 이용하여 주변의 시차벡터를 예측 파라미터로 사용함으로써 계산량을 감소시킬 수 있었다. 또한, 예측 오차가 큰 객체의 경계면에서 블록의 크기를 4분할로 분할하여 시차 벡터를 재검색 하는 기법으로 경계 블록에 대한 예측 오차를 감소시킬 수 있었다. 모의 실험 결과 기존의 블록정합기법(BMA)에 비해 최대 75%의 계산량이 감소하였으며, PSNR 측면에서도 0.3dB이상 개선되었다.

• The KIPS Transactions:PartB
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• v.11B no.3
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• pp.309-316
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• 2004

In this paper, we proposed the TDS(T-shape Diamond Search) based on the directions of above, below, left and right points to estimate the motion vector fast and more correctly in this method, we exploit the facts that most motion vectors are enclosed in a circular region with a radius of 2 fixels around search center(0,0). At first, the 4 points in the above, below, left and right around the search center is calculated to decide the point of the MBD(Minimum Block Distortion). And then w. above point of the MBD is checked to calculate the SAD. If the SAD of the above point is less than the previous MBD, this process is repeated. Otherwise, the right and left points of MBD are calculated to decide The points that have the MBD between right point and left point. Above processes are repeated to the predicted direction for motion estimation. Especially, if the motions of image are concentrated in the crossing directions, the points of other directions are omitted. As a result, we can estimate motion vectors fast. Experiments show that the speedup improvement of the proposed algorithm over Diamond Search algorithm(DS) and HEXgon Based Search(HEXBS) can be up to 38∼50％ while maintaining similar image Quality.

• Proceedings of the Korea Information Processing Society Conference
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• 2005.05a
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• pp.181-184
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• 2005

기존의 비디오 분할 방법은 밝기의 변화가 큰 영상이나 움직임이 큰 영상에 대해서는 정확한 분할이 이루어지지 않았다. 본 논문은 움직임 정보를 이용하여 움직임이 큰 영상에서 좀 더 정확하게 비디오를 분할할 수 있는 방법을 제안한다. 이를 위해 블록 정합 알고리즘을 이용하여 얻어진 움직임 벡터로부터 움직임 유사도를 찾는 방법을 제안한다. 또 연속된 프레임에서 픽셀의 차이 값을 계산할 때 motion blur 로 생기는 오차를 각 블록의 움직임 크기로 보상하여 좀 더 정확한 픽셀의 차이 값을 계산하는 방법을 제안한다. 이렇게 얻어진 두 가지 정보를 이용하여 discontinuity value 를 계산한다. 움직임이 많은 액션 영화 3 편에 대해 실험한 결과 제안한 방법이 기존의 움직임 유사도와 픽셀 차이 값을 구하여 샷 경계 검출을 하는 방법보다 좀 더 정확한 샷 경계 검출을 하고 있다는 것을 보여준다.

• Journal of the Korea Society of Computer and Information
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• v.5 no.3
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• pp.91-98
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• 2000

In this paper we design implement the speaker verification system for verifying personal identification using voice. Filter bank magnitude was used as a feature parameter and code-book was made using LBG a1gorithm. The code book convert feature parameters into code sequence. The difference between reference pattern and input pattern measures using DTW(Dynamic Time Warping). The similarity measured using DTW and threshold value derived from deviation were used to discriminate impostor from client speaker.

• Journal of the Korea Society of Computer and Information
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• v.8 no.4
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• pp.13-20
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• 2003

Based on the studies on the motion vector distributions estimated on the image sequences, we proposed constrained diamond search (DS) algorithm for fast block-matching motion estimation. By considering the fact that motion vectors are searched within the 2 pixels distance in vertically and horizontally on average, we confirmed that DS algorithm achieves close performance on error ratio and requires less computation compared with new three-step search (NTSS) algorithm. Also, by applying displaced frame difference (DFD) to DS algorithm, we reduced the computational loads needed to estimate the motion vectors within the stable block that do not have motions. And we reduced the possibilities falling into the local minima in the course of estimation of motion vectors by applying DFD to DS algorithm. So, we knew that proposed constrained DS algorithm achieved enhanced results as aspects of error ratio and the number of search points to be necessary compared with conventional DS algorithm, four step search (FSS) algorithm, and block-based gradient-descent search algorithm

• The KIPS Transactions:PartB
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• v.19B no.2
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• pp.113-122
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• 2012

This paper presents a new stereo matching technique which is based on the matching of feature windows and feature links. The proposed method uses the FAST feature detector to find image features in stereo images and determines the correspondences of the detected features in the stereo images. We define a feature window which is an image region containing several image features. The proposed technique consists of two matching steps. First, a feature window is defined in a standard image and its correspondence is found in a reference image. Second, the corresponding features between the matched windows are determined by using the feature link technique. If there is no correspondence for an image feature in the standard image, it's disparity is interpolated by neighboring feature sets. We evaluate the accuracy of the proposed technique by comparing our results with the ground truth of in a stereo image database. We also compare the matching accuracy and computation time with two conventional feature-based stereo matching techniques.

• Proceedings of the KSRS Conference
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• 2006.03a
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• pp.169-172
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• 2006

본 논문에서는 1m 해상도의 위성영상으로부터 건물의 경계선을 검출하기 위해 영상분할과 변이지도(disparity map)를 이용하는 새로운 방법을 제안한다. Watershed 방법으로 영상을 분할하고 분할된 영역 내부의 변이를 다중정합창틀(multiple matching window)과 결합된 다차원특징벡터정합(multi-dimensional feature vector matching)을 이용하여 계산한다 분할된 인접 영역들 가운데 panchromatic 및 multispectral 밝기값과 변이의 평균값이 유사하면 두 영역을 결합하여 하나의 영역을 생성하고 이 과정을 반복적으로 수행한다. 영역의 평균 변이값이 기준 값보다 크면 이를 건물 지붕 영역으로 결정한다. IKONOS 위성영상에 제안한 방법을 적용하여 작은 건물이 밀집되어 있는 도시 지역에서 건물 지붕의 영역과 경계선을 효과적으로 검출할 수 있었다.

• Journal of Biomedical Engineering Research
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• v.19 no.3
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• pp.233-242
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• 1998

In anatomical aspects, magnetic resonance image offers more accurate information than other medical images such as X ray ultrasonic and CT images. This paper introduces a method that recognizes disk diseases from spine MR images. In this method, image enhancement, image segmentation and feature extraction for sagittal plane and axial plane images are performed to separate the disk region. And then template matching method is used to extract disease region for axial plane imges. Finally, disease feature vectors are integrated and disease discrimination processes are performed. Experimental results show that the proposed method discriminates between normal and diseased disk with a considerable recognition ratio.