• Proceedings of the Korea Information Processing Society Conference
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• 2011.11a
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• pp.422-424
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• 2011

시각장애인이 책을 읽을 수 있는 방법은 점자책 또는 오디오북이 있다. 그러나 점자책과 오디오북은 그 개수가 한정적이다. 또한, 점자책과 오디오북을 제작하는 데에는 상당한 시간이 소요된다. 이로 인해 시각장애인의 기본적인 독서권이 침해 받고 있다. 이러한 문제점을 해결하기 위해 영상처리, OCR, TTS 기법을 적용해 시각장애인용 독서 스탠드를 개발하였다. 제안하는 시스템에서는 문자 인식률 향상을 위해 왜곡된 이미지를 보정한 후 단편 블록화 과정을 추가로 적용하여 문자 인식률을 93%까지 증가시켜 실용성을 높였다. 개발된 시스템은 도서관 및 서점 등에 설치되어 시각장애인의 독서권을 확보하는데 도움이 될 것으로 기대된다.

• Journal of Korea Multimedia Society
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• v.11 no.1
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• pp.53-60
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• 2008

Fingerprint verification method based on minutiae has been widely used for its speed and size stemming from utilizing only a few data, but it is vulnerable to some errors caused by the false minutiae extractions. A number of suggestions have been made to correct these problems. However, because it is very difficult to avoid all the external factors, such as noises that occur when fingerprints are collected, and all the internal factors that occur during the process of them, there is a limit in minimizing errors by improving the whole process. On the other hand, a fingerprint verification method based on images yields fewer errors because it makes direct comparison between images not using minutiae. Image-based fingerprint verification method has its limitations in aligning images with accuracy. Therefore, this paper proposes a new methodology to improve the performance utilizing both image-based and minutiae-based verification methods effectively. As the result of experimenting with both images and minutiae, the false accept rate and the false reject rate have been improved from 2.7% to 0.8% and from 6.5% to 5.5%, respectively.

• Journal of Korea Multimedia Society
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• v.3 no.6
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• pp.586-591
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• 2000

Color pictures on CPT are generally affected by the receiver characteristic and the condition of exterior illuminants. Moreover, readjustment of incorrect color in the CPT causes color distortion on a given picture. This paper describes a color adjustment method for modelling of CPT at the view point of observer in the ordinary lighting condition. To develop this method, we proposed ways of luminance recompensation under the gamma transformation for the intensity of illuminant, hue/saturation compensation for the types of illuminant and control of specific color for the reference. Based on these method, a color correlation system is suggested with the goal of reducing the color errors which are represented due to the influence of reflectance component of illuminants, the gamma transformation of CPT and the frequently adjustment of reference scene to set a optimum color.

• Journal of Broadcast Engineering
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• v.19 no.5
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• pp.677-686
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• 2014

This paper analyzes the 3D accuracy of stereo images captured from a mobile phone. For 3D accuracy evaluation, we have compared the accuracy result according to the amount of the convergence angle. In order to calculate the 3D model space coordinate of control points, we perform inner orientation, distortion correction and image geometry estimation. And the quantitative 3D accuracy was evaluated by transforming the 3D model space coordinate into the 3D object space coordinate. The result showed that relatively precise 3D information is generated in more than $17^{\circ}$ convergence angle. Consequently, it is necessary to set up stereo model structure consisting adequate convergence angle as an measurement distance and a baseline distance for accurate 3D information generation. It is expected that the result would be used to stereoscopic 3D contents and 3D reconstruction from images captured by a mobile phone camera.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.10 no.3
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• pp.556-563
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• 2006

We should extract lines and data which consist of the table in order to classify the table region and analyze its structure in document image. But it is difficult to extract lines and data exactly because the lines are cut and their lengths are changed, or characters or noises are merged to the table lines. These problems result from the error of image input device or image reduction. In this paper, we propose the better method of extracting lines and data for table region classification and structure analysis than the previous ones including commercial softwares. The prposed method extracts horizontal and vertical lines which consist of the table by the use of one dimensional median filter. This filter not only eliminates the noises which attach to the line and the lines which are orthogonal to the filtering direction, but also connects the cut line of which the gap is shorter than the length of the filter tap in the process of extracting lines to the filtering direction. Furthermore, texts attached to the line are separated in the process of extracting vertical lines. This is an example of ABSTRACT format.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.39C no.1
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• pp.28-35
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• 2014

Surveillance cameras in national border and coastline area often occur the video distortion because of rapidly changing weather and light environments. It is positively necessary to enhance the distorted video quality for keeping surveillance. In this paper, we propose an adaptive video enhancement algorithm in the various environment changes. To solve an unstable performance problem of the existing method, the proposed method is based on Retinex algorithm and uses enhanced curves which is adapted in foggy and low-light conditions. In addition, we mixture the weighted HSV color model to keep color constancy and reduce noise to obtain clear images. As a results, the proposed algorithm improves the performance of well-balanced contrast enhancement and effective color restoration without any quality loss compared with the existing algorithm. We expect that this method will be used in surveillance camera systems and offer help of national defence with reliability.

• Journal of Korea Multimedia Society
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• v.15 no.1
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• pp.9-17
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• 2012

Recently, a new image appearance model, named iCAM06, was developed for High-Dynamic-Range (HDR) image rendering. The dynamic range of a HDR image needs to be mapped on the range of output devices, which is called the tone reproduction or tone mapping. The iCAM06, the representative HDR rendering algorithm also uses the tone compression using a S-curve mapping function for image reproduction on the dynamic range of output devices. However the iCAM06 occurs white point shift during its tone compression process. Therefore, we propose a compensation method for white point shift problem using the corrected channel gain function. Experiment results show that the proposed method has better performance than the iCAM06.

• The Bulletin of The Korean Astronomical Society
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• v.37 no.2
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• pp.229.2-229.2
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• 2012

지금까지 해외의 여러 달 궤도선에서 달의 영상을 다양한 방법으로 관측한 것에서 알 수 있듯이 영상 관측은 달 탐사에서 중요한 부분이다. 특히 그 중에서 입체 영사기(Stereo Imager)는 달의 3차원적 영상을 관측하여 달 표면의 구조를 파악할 수 있고 분광 카메라(Hyperspectral Camera)는 달 표면을 이루고 있는 물질을 분광 정보를 통해서 알아낼 수 있다. 본 연구에서는 우리나라가 2020년경 독자적인 달 궤도선을 계획하고 있는 것에 발맞추어 이 두 관측 장비를 설계해 보았다. 본 연구에서 설계한 탑재체는 하나의 광학계를 이용해 가시광 영역에서 동시에 입체 영상과 분광 영상을 얻을 수 있는 장치이며, 달 표면에서의 궤도선의 속도와 저장 가능한 정보의 양을 고려하여 100 km의 고도에서 속도를 1.6 km/s로 가정할 때 interline CCD가 17.5 m의 공간 분해능을 갖기 위해 92 frame/s 이상의 frame rate로 관측을 수행할 수 있게 하였다. 특히 분광 카메라는 wedge filter를 사용하여 광학계의 부담을 줄였으며 검출기로는 interline CCD를 사용하여 channel 수를 조절할 수 있도록 하였다. 또한 달 표면을 구성하는 입자의 크기에 대한 정보를 얻을 수 있는 편광판도 설치 하였다. 시험 모델의 문제점을 분석하여 새롭게 개선된 탑재체를 설계하여 개발하였다. 렌즈를 수정해 vignetting과 왜곡 현상을 보정하였고 전체 무게를 1.5 kg으로 줄여서 시험 모델보다 30% 이상 줄일 수 있었다. 파장 분해능은 20nm로 시험모델보다 더 개선된 분해능을 얻을 수 있었다. 출력 효율의 증대를 위해 power board의 수정을 수행하였다.

• Sleep Medicine and Psychophysiology
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• v.25 no.2
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• pp.82-91
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• 2018

Objectives: Synchronous electroencephalogram (EEG) and functional magnetic resonance imaging (fMRI) has been used to explore sleep stage dependent functional brain networks. Despite a growing number of sleep studies using EEG-fMRI, few studies have conducted network analysis on whole night sleep due to difficulty in data acquisition, artifacts, and sleep management within the MRI scanner. Methods: In order to perform network analysis for whole night sleep, we proposed experimental procedures and data processing techniques for EEG-fMRI. We acquired 6-7 hours of EEG-fMRI data per participant and conducted signal processing to reduce artifacts in both EEG and fMRI. We then generated a functional brain atlas with 68 brain regions using independent component analysis of sleep fMRI data. Using this functional atlas, we constructed sleep level dependent functional brain networks. Results: When we evaluated functional connectivity distribution, sleep showed significantly reduced functional connectivity for the whole brain compared to that during wakefulness. REM sleep showed statistically different connectivity patterns compared to non-REM sleep in sleep-related subcortical brain circuits. Conclusion: This study suggests the feasibility of exploring functional brain networks using sleep EEG-fMRI for whole night sleep via appropriate experimental procedures and signal processing techniques for fMRI and EEG.

• Korean Journal of Optics and Photonics
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• v.34 no.3
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• pp.99-105
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• 2023

The performance of astronomical telescopes can be negatively affected by atmospheric turbulence. To address this issue, techniques for atmospheric turbulence correction have been developed, requiring the simulation of atmospheric turbulence in the laboratory. The most practical way to simulate atmospheric turbulence is to use a phase plate. When measuring a phase plate that simulates strong turbulence, a Shack-Hartmann wave-front sensor is commonly used. However, the laser power decreases as it passes through the phase plate, potentially leading to a weak laser signal at the sensor. This paper investigates the need to control the laser power when measuring a phase plate that simulates strong atmospheric turbulence, and examines the effects of the laser power on the measured wavefront. For phase plates with relatively high Fried parameter r₀, the laser power causes a variation of over 10% in r₀. For phase plates with relatively low r₀, the laser power causes a variation of less than 5%, which means that the influence of the laser power is negligible for phase plates that simulate strong atmospheric turbulence. Based on the system described in this paper, a phase plate simulating strong atmospheric turbulence can be measured at a laser power of 5 mW or higher. Therefore, controlling the laser's output power is necessary when measuring a phase plate for simulating atmospheric turbulence, especially for phase plates with low r₀ values.