• ETRI Journal
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• 제42권2호
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• pp.258-271
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• 2020

A correlation exists between luminance samples and chrominance samples of a color image. It is beneficial to exploit such interchannel redundancy for color image compression. We propose an algorithm that predicts chrominance components Cb and Cr from the luminance component Y. The prediction model is trained by supervised learning with Laplacian-regularized least squares to minimize the total prediction error. Kernel principal component analysis mapping, which reduces computational complexity, is implemented on the same point set at both the encoder and decoder to ensure that predictions are identical at both the ends without signaling extra location information. In addition, chrominance subsampling and entropy coding for model parameters are adopted to further reduce the bit rate. Finally, luminance information and model parameters are stored for image reconstruction. Experimental results show the performance superiority of the proposed algorithm over its predecessor and JPEG, and even over JPEG-XR. The compensation version with the chrominance difference of the proposed algorithm performs close to and even better than JPEG2000 in some cases.

• 한국해양공학회지
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• 제22권4호
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• pp.90-96
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• 2008

In general, the swing motions of a crane are controlled and suppressed by controlling the trolley motion. In many of our previous studies, we suggested a new type of anti-sway control system for a crane. In this proposed control system, a small auxiliary mass (moving-mass) is installed on the spreader and moving this auxiliary mass controls tire swing motion. The actuator reaction against the auxiliary mass applies inertial control forces to the container in order to reduce the swing motion in the desired manner. However, measuring systems based on a laser sensor or other means are not veryuseful in real-worldapplications. So, in this paper, animage sensor is used to measure the motions of the spreader and the measured data are fed back to the controller in real time. The applied image processing technique is a kind of robust template matching method called Vector Code Correlation (VCC), which was devised to consider real environmental conditions. The H $\infty$ based control technique is applied to suppress the swing motion of the crane. Experimental results showed that the proposed measurement and control system based on an image sensor is useful and robust to disturbances.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1988년도 한국자동제어학술회의논문집(국내학술편); 한국전력공사연수원, 서울; 21-22 Oct. 1988
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• pp.183-186
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• 1988

The problem addressed in this paper is the accurate tracting of a dynamic target using outputs from a forward - looking infrared(FLIR) sensor as measurements. The important variations are 1) the spread of the target intensity pattern in the FLIR image plane, 2) target motion characteristics, and 3) the rms value and both spartial and temporal correlation of the back - ground noise. Based on this insights. design modifications and on - line adaptation copabilities are incorporated to enable this type of filter track highly maneuverable targets such as air-to-air missiles, with spatially distributed and changing image intensity profiles, against, background clutter.

• Journal of Electrical Engineering and Technology
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• 제10권6호
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• pp.2384-2392
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• 2015

The technical development and practical applications of big-data for health is one hot topic under the banner of big-data. Big-data medical image fusion is one of key problems. A new fusion approach with coding based on Spherical Coordinate Domain (SCD) in Wireless Sensor Network (WSN) for big-data medical image is proposed in this paper. In this approach, the three high-frequency coefficients in wavelet domain of medical image are pre-processed. This pre-processing strategy can reduce the redundant ratio of big-data medical image. Firstly, the high-frequency coefficients are transformed to the spherical coordinate domain to reduce the correlation in the same scale. Then, a multi-scale model product (MSMP) is used to control the shrinkage function so as to make the small wavelet coefficients and some noise removed. The high-frequency parts in spherical coordinate domain are coded by improved SPIHT algorithm. Finally, based on the multi-scale edge of medical image, it can be fused and reconstructed. Experimental results indicate the novel approach is effective and very useful for transmission of big-data medical image(especially, in the wireless environment).

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 2002년도 Proceedings of International Symposium on Remote Sensing
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• pp.518-523
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• 2002

Nowadays the Rational Function Model (RFM), an abstract sensor model, is substituting physical sensor models for highly complicated imaging geometry. But RFM is algorithm to be required many Ground Control Points (GCP). In case of RFM of the third order, At least forty GCP are required far RFM generation. The purpose of this study is to research more efficient algorithm on GCP and accurate algorithm similar to RFM. The Polynomial Camera Model is relatively accurate and requires a little GCP in comparisons of RFM. This paper introduces how to generate Polynomial Camera Model and fundamental algorithms for construction of 3-D topographic data using the Polynomial Camera Model information in the Kompsat stereo pair and describes how to generate the 3-D ground coordinates by manual matching. Finally we tried to extract height information for the whole image area with the stereo matching technique based on the correlation.

• 한국측량학회지
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• 제38권2호
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• pp.165-172
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• 2020

There is growing interest in Vision-based video image matching owing to the constantly developing technology of unmanned-based systems. The purpose of this paper is the development of a fast and effective matching technique for the UAV oblique video image. We first extracted initial matching points using NCC (Normalized Cross-Correlation) algorithm and improved the computational efficiency of NCC algorithm using integral image. Furthermore, we developed a triangulation-based outlier removal algorithm to extract more robust matching points among the initial matching points. In order to evaluate the performance of the propose method, our method was quantitatively compared with existing image matching approaches. Experimental results demonstrated that the proposed method can process 2.57 frames per second for video image matching and is up to 4 times faster than existing methods. The proposed method therefore has a good potential for the various video-based applications that requires image matching as a pre-processing.

• Current Optics and Photonics
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• 제5권4호
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• pp.362-369
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• 2021

Absolute position sensors are widely used in machine tools and precision measuring instruments because measurement errors are not accumulated, and position measurements can be performed without initialization. The laser speckle-based absolute position sensor, in particular, has advantages in terms of simple system configuration and high measurement accuracy. Unlike traditional absolute position sensors, it does not require an expensive physical length scale; instead, it uses a laser speckle image database to measure a moving surface position. However, there is a problem that a huge database is required to store information in all positions on the surface. Conversely, reducing the size of the database also decreases the accuracy of position measurements. Therefore, in this paper, we propose a new method to measure the surface position with high precision while reducing the size of the database. We use image stitching and approximation methods to reduce database size and speed up measurements. The absolute position error of the proposed method was about 0.27 ± 0.18 ㎛, and the average measurement time was 25 ms.

• 한국광학회지
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• 제17권5호
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• pp.383-390
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• 2006

Shack-Hartmann 파면측정 센서는 적응광학 분야에서 파면측정용으로 가장 널리 사용되고 있다. Shack-Hartmann 센서에서 파면측정 알고리즘은 크게 점영상의 중심점 탐색 알고리즘과 파면복원 알고리즘으로 나눌 수 있다. 이 중 점영상의 중심점 탐색은 파면측정 결과에 크게 영향을 미치나 많은 연구결과에도 불구하고 최적의 중심점 측정 알고리즘 및 내부 변수 설정에 대한 일반적인 해결책은 아직 제시되지 못하고 있다. 현재, 중심점 탐색 알고리즘으로는 무게중심법(center of gravity)이 가장 널리 사용되고 있다. 본 연구에서는 중심점 탐색 알고리즘에 의한 측정 정확도 분석을 위해 무게중심법과 상관관계법(correlation)을 함께 고려하였다. 이를 위해 Shack-Hartmann 센서의 파면측정 과정을 전산모사하였고, 이로부터 중심점 탐색 알고리즘과 관련하여 무게중심법 및 상관관계법에서의 노이즈 특성을 비교, 분석하였다. 또한, 무게중심법에서 문턱값(threshold value)의 설정에 따른 파면측정의 정확도에 대한 분석을 통하여 노이즈 제거를 위한 최적의 문턱값을 제안하였다. 이와 더불어 Shack-Hartmann 센서 시스템을 구성하여 디포커스(defocus)를 발생시키고 이를 측정하는 실험을 수행함으로써 파면측정 알고리즘 및 전산모사 결과를 검증하였다.

• 한국군사과학기술학회지
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• 제26권1호
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• pp.22-30
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• 2023

When tracking small UAVs and drone targets in cloud clutter environments, MWIR sensors are often unable to track targets continuously. To overcome this problem, the SWIR sensor is mounted on the same gimbal. Target tracking uses sensor information fusion or selectively applies information from each sensor. In this case, parallax correction using the target distance is often used. However, it is difficult to apply the existing method to small UAVs and drone targets because the laser rangefinder's beam divergence angle is small, making it difficult to measure the distance. We propose a tracking method which needs not parallax correction of sensors. In the method, images from MWIR and SWIR sensors are captured simultaneously and a tracking error for gimbal driving is chosen by effectiveness measure. In order to prove the method, tracking performance was demonstrated for UAVs and drone targets in the real sky background using MWIR and SWIR image sensors.

• 한국측량학회지
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• 제29권2호
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• pp.175-181
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• 2011

원격탐사 분야에서 고해상도의 멀티스펙트럴 영상은 위성센서의 기술적인 제약 때문에 직접적으로 취득하기 어렵다. 이러한 문제를 극복하기 위하여 다양한 위성영상 융합 기법이 제안되어졌다. 그러나, 대부분의 영상융합기법들은 원 멀티스펙트럴 영상의 분광정보를 왜곡시키거나 고해상도 흑백영상의 공간해상도에 비하여 융합영상의 공간해상도가 저하되는 문제점을 지닌다. 최근 들어 융합영상의 분광왜곡을 최소화시키면 서 공간해상도를 효율적으로 증가시킬 수 있는 공간상관도 기반의 하이브리드 융합 기법이 제안되었다. 본 연구에서는 하이브리드 융합기법에 다양한 공간상관도 추출 식을 적용하여 보고 이에 따른 분광/공간정보 왜곡의 양을 비교 평가하였다. 실험 결과 라플라시안 필터를 이용한 하이브리드 융합 기법이 다른 고주파 정보 추출 기법에 비하여 하이브리드 융합 기법에 효과적으로 적용할 수 있다는 것을 확인할 수 있었다.