• 한국멀티미디어학회논문지
• /
• 제19권5호
• /
• pp.881-889
• /
• 2016

Ocular region recently emerged as a new biometric trait for overcoming the limitations of iris recognition performance at the situation that cannot expect high user cooperation, because the acquisition of an ocular image does not require high user cooperation and close capture unlike an iris image. This study proposes a new method for ocular image recognition based on BRISK (binary robust invariant scalable keypoints). It uses the distance ratio of the two nearest neighbors to improve the accuracy of the detection of corresponding keypoint pairs, and it also uses geometric constraint for eliminating incorrect keypoint pairs. Experiments for evaluating the validity the proposed method were performed on MMU public database. The person recognition rate on left and right ocular image datasets showed 91.1% and 90.6% respectively. The performance represents about 5% higher accuracy than the SIFT-based method which has been widely used in a biometric field.

• Journal of information and communication convergence engineering
• /
• 제13권4호
• /
• pp.270-274
• /
• 2015

In this paper, we propose an improved framework to analyze an N-ocular imaging system under fixed constrained resources such as the number of image sensors, the pixel size of image sensors, the distance between adjacent image sensors, the focal length of image sensors, and field of view of image sensors. This proposed framework takes into consideration, for the first time, the defocusing effect of the imaging lenses according to the object distance. Based on the proposed framework, the N-ocular imaging system such as integral imaging is analyzed in terms of depth resolution using two-point-source resolution analysis. By taking into consideration the defocusing effect of the imaging lenses using ray projection model, it is shown that an improved depth resolution can be obtained near the central depth plane as the number of cameras increases. To validate the proposed framework, Monte Carlo simulations are carried out and the results are analyzed.

• 대한전자공학회논문지
• /
• 제24권5호
• /
• pp.856-862
• /
• 1987

An local adaptive image segmentatin algorithm for local feature detection and effective clustering of unimodal histogram shape are proposed. Local adaptive difference image and its histogram are obtained from the input image. The parameters are derived from the histogram and used for the segmentation based on relaxatin process. The results showed effective region segmentation and good noise cleaning for the ocular fundus fluorescein angiogram which has low contrast and unimodal histogram.

• 한국산학기술학회논문지
• /
• 제7권6호
• /
• pp.1257-1263
• /
• 2006

다양한 의료진단 자동화 기기들이 개발되고 있으나 대부분 서양의학에 집중되어 있는 현실이고, 한의학의 진단시 자동화 및 정량화를 위한 장치 개발은 미미하다. 한편, 한의학에서의 네가지 진단 방법 중 하나인 망진은 환자의 관형과 찰색을 통해 질병의 유무와 경중을 진단한다. 망진을 시행할 때 얼굴에서 이목구비와 명당 부위의 상태가 특히 중요하다. 본 논문에서는 얼굴 영상으로부터 망진을 위한 얼굴 요소들을 추출하기 위한 방법을 제안하고, 남여 얼굴 영상에 대한 실험을 통해 제안한 방법의 유용성을 보이고자 한다.

• Current Optics and Photonics
• /
• 제3권6호
• /
• pp.597-604
• /
• 2019

This study was performed to evaluate objective visual quality and ocular scattering in myopic refractive-surgery patients, compared to emmetropes. Optical vision-quality parameters (modulation transfer function (MTF) cutoff and Strehl ratio) and objective scattering index (OSI) were measured using an optical quality analysis system (OQAS II) based on the double-pass technique. In all subjects, the higher the MTF cutoff and Strehl ratio, the lower the OSI and ocular higher-order aberrations (HOAs). The MTF cutoff and Strehl ratio for the laser-assisted subepithelial keratectomy (LASEK) group were lower than those for the emmetropia group, while the OSI, ocular HOAs, and spherical aberration (SA) for the LASEK group were higher than those for emmetropia group. Ocular scattering would be one of the important factors in regard to visual quality. Therefore, the quality of the retinal image in the LASEK patients has been shown to reduce the quality of vision more than in the emmetropes.

• Annals of Clinical Neurophysiology
• /
• 제1권2호
• /
• pp.173-181
• /
• 1999

Eye movements serve vision by placing the image of an object on the fovea of each retina, and by preventing slippage of images on the retina. The brain employs two modes of ocular motor control, fast eye movements (saccades) and smooth eye movements. Saccades bring the fovea to a target, and smooth eye movements prevent retinal image slip. Smooth eye movements comprise smooth pursuit, the optokinetic reflex, the vestibulo-ocular reflex (VOR), vergence, and fixation. Saccades achieve rapid refixation of targets that fall on the extrafoveal retina by moving the eyes at peak velocities that can exceed $700^{\circ}/s$. Various brain lesions can affect saccadic latency, velocity, or accuracy. Smooth pursuit maintains fixation of a slowly moving target. The pursuit system responds to slippage of an image near the fovea in order to accelerate the eyes to a velocity that matches that of the target. When smooth eye movements velocity fails to match target velocity, catch-up saccades are used to compensate for limited smooth pursuit velocities. The VOR subserves vision by generating conjugate eye movements that are equal and opposite to head movements. If the VOR gain (the ratio of eye velocity to head velocity) is too high or too low, the target image is off the fovea, and head motion causes oscillopsia, an illusory to-and-fro movement of the environment.

• 대한의용생체공학회:의공학회지
• /
• 제26권3호
• /
• pp.133-138
• /
• 2005

This paper presents a new method for measuring ocular torsion using the optical flow. Images of the iris were cropped and transformed into rectangular images that were orientation invariant. Feature points of the iris region were selected from a reference and a target image, and the shift of each feature was calculated using the iterative Lucas-Kanade method. The feature points were selected according to the strength of the corners on the iris image. The accuracy of the algorithm was tested using printed eye images. In these images, torsion was measured with $0.15^{\circ}$ precision. The proposed method shows robustness even with the gaze directional changes and pupillary reflex environment of real-time processing.

• Annals of Clinical Neurophysiology
• /
• 제25권2호
• /
• pp.55-65
• /
• 2023

The ultimate role of ocular movements is to keep the image of an object within the fovea and thereby prevent image slippage on the retina. Accurate evaluations of eye movements provide very useful information for understanding the functions of the oculomotor system and determining abnormalities therein. Such evaluations also play an important role in enabling accurate diagnoses by identifying the location of lesions and discriminating from other diseases. There are various types of ocular movements, and this article focuses on saccades, fast eye movements, smooth pursuit, and slow eye movements, which are the most important types of eye movements used in evaluations performed in clinical practice.

• 한국안광학회지
• /
• 제16권1호
• /
• pp.83-90
• /
• 2011

목적: 일반 2D영상과 anaglyph 3D입체 영상을 시청했을 때 나타나는 자각 증상과 입체시 관련성을 비교 평가하고자 하였다. 방법: 20-30세의 대학생 70명(남 38명, 여 32명)을 대상으로 2D영상과 적록안경방식의 anaglyph 3D영상을 각각 30분 시청한 후 자각 증상을 설문 조사하였고, 2D영상과 3D영상 시청 전 후의 Titmus circles 및 TNO입체시를 평가하여 시각적 자각 증상과 입체시의 상관관계를 평가하였다. 결과: 2D영상과 3D영상 시청 후의 시각과 비시각적 자각 증상 모두 3D영상에서 높게 나타났다. 편광방식의 Titmus circles 입체시는 2D 및 3D영상 시청전과 후의 변화는 없는 것으로 나타났지만 적록안경방식의 TNO 입체시는 3D영상을 시청 후 더 좋은 것으로 나타났다. 3D영상 시청 후 시각적 자각 증상과 TNO 입체시는 증가하였고, 뚜렷한 상관관계(r=0.605)를 보였다. 결론: 시청 전의 입체시가 좋으면 3D영상 시청에서 상대적으로 시각적 자각 증상은 낮았다. 그러나 단시간 anaglyph 3D영상 시청에서 자각 증상이 증가되며, TNO 입체시의 향상은 시각적 자각 증상 완화와 관련성이 낮은 것으로 평가된다. 이러한 경향은 적록안경방식의 anaglyph 3D영상에 대한 적응 과정의 하나로 여겨진다.

• 대한의용생체공학회:의공학회지
• /
• 제11권1호
• /
• pp.31-38
• /
• 1990

Image correction of the fluorescein angiogram with the low contrast and geometrically distorted is studied. The procedure is divided into two steps : A template matching step and a geometrical transformation step. Based on the sequential similiarity detection algorithm, more Improved matching results are obtained with edge enhanced image. For the reference points and the corresponding matchimg points, the geometrical transformationss by the use of the average value of the X, Y translational shifts and a pair of these points, respectively are described. Then the corrected images are obtained using bilinear interpolation. It is proven that the usefullness of this study for the image correction of the ocular fundus fluoresceln angiogram with low contrast and geometrically distorted mainly due to the eye movements.