• Journal of Korea Multimedia Society
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• v.19 no.5
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• pp.881-889
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• 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
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• v.13 no.4
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• pp.270-274
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• 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.

• Journal of the Korean Institute of Telematics and Electronics
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• v.24 no.5
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• pp.856-862
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• 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.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.7 no.6
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• pp.1257-1263
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• 2006

Many automatic medical devices have been invented and developed mostly for the western medicine, not for the oriental medicine. Facial ocular inspection is one of the four diagnosis methods of oriental medicine, which makes a diagnosis of disease by observing the shape and color of patient's vital organs. In facial ocular inspection, the regions of five sensory organs and Myungdang are specially important. In this paper, we propose a novel method to extract the five sensory organ and Myungdang from a facial image for facial ocular inspection. Finally, we show the usefulness of the proposed method by experiments.

• Current Optics and Photonics
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• v.3 no.6
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• pp.597-604
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• 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
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• v.1 no.2
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• pp.173-181
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• 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.

• Journal of Biomedical Engineering Research
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• v.26 no.3
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• pp.133-138
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• 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
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• v.25 no.2
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• pp.55-65
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• 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.

• Journal of Korean Ophthalmic Optics Society
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• v.16 no.1
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• pp.83-90
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• 2011

Purpose: This study aimed to compare and assess whether there was a relation between self-reported symptom and stereopsis in viewing an anaglyph 3D and a general 2D image. Methods: Seventy subjects (38 males, 32 females) were students ranging in age from 20 to 30 years. Subjects' symptoms were investigated by a questionnaire after viewing the 2D image and the anaglyph 3D image using red-green glasses for 30 minutes. Titmus circles and TNO stereopsis tests were performed before and after the images. A correlation between symptom and stereopsis was evaluated. Results: Both ocular and nonocular symptom in viewing 3D image were higher than those in 2D image. Titmus circles stereopsises using polarized filters were not changed before and after viewing images, but TNO stereopsises using color filters such as red-green glasses were increased after viewing 3D image. Ocular symptom and TNO stereopsis were increased after viewing 3D image, and there was a good correlation between them (r=0.605). Conclusions: Better stereopsises before viewing 3D are relatively lower ocular symptoms in viewing 3D image. But symptoms are increased in viewing anaglyph 3D image for a short-time and improvement of TNO steropsis is poorly associated with the relief of ocular symptoms. This tendency seems to be related with an adaptation to anaglyph 3D image with red-green glasses.

• Journal of Biomedical Engineering Research
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• v.11 no.1
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• pp.31-38
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• 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.