• The Transactions of the Korean Institute of Electrical Engineers A
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• v.48 no.10
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• pp.1311-1316
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• 1999

A visual servoing method has been proposed based on disturbance observer to eliminate the effect of the off-diagonal component of image feature Jacobian, since performance indices such as measurement sensitivity of visual features, sensitivity of the control to noise and controllability could be improved when an image feature Jacobian was given as a block diagonal matrix. In this paper, experimental results of disturbance observer-based visual servoing are discussed where Samsung FARAMAN-AS1 6-axis industrial robot manipulator is employed. Also, the feature saturator is proposed to stabilize the disturbance observer loop by saturating the differential changes of the image features.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.5 no.2
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• pp.390-407
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• 2011

Three-dimensional (3D) video technologies are becoming increasingly popular, as it can provide users with high quality and immersive experiences. However, color inconsistency between the camera views is an urgent problem to be solved in multi-view imaging. In this paper, a perception-based color correction method for multi-view images is proposed. In the proposed method, human visual sensitivity (VS) and visual attention (VA) models are incorporated into the correction process. Firstly, the VS property is used to reduce the computational complexity by removing these visual insensitive regions. Secondly, the VA property is used to improve the perceptual quality of local VA regions by performing VA-dependent color correction. Experimental results show that compared with other color correction methods, the proposed method can greatly promote the perceptual quality of local VA regions greatly and reduce the computational complexity, and obtain higher coding performance.

• Journal of Broadcast Engineering
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• v.19 no.4
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• pp.468-477
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• 2014

This paper proposes a novel perceptual quality-based (PQ-based) video coding method with foveated contrast sensitivity (FCS). Conventional methods on PQ-based video coding with FCS achieve minimum loss on perceptual quality of compressed video by exploiting the property of human visual system (HVS), that is, its sensitivity differs by the spatial frequency of visual stimuli. On the other hand, PQ-based video coding with foveated masking (FM) exploits the difference of the sensitivity of the HVS between the central vision and the peripheral vision. In this study, a novel FCS model is proposed which considers both the conventional DCT-based JND model and the FM model. Psychological study is conducted to construct the proposed FCS model, and the proposed model is applied to PQ-based video coding algorithm implemented on HM10.0 reference software. Experimental results show that the proposed method decreases bitrate by the average of 10% without loss on the perceptual quality.

• Asian Pacific Journal of Cancer Prevention
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• v.14 no.12
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• pp.7761-7762
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• 2013

Alternative strategies such as visual inspection of cervix with acetic acid, are real time, economical and easily implemented methods for cervical cancer screening. However, variable sensitivity and specificity have been observed in various community based studies. The possible reasons could include variation in man power training, light source used for visualization, and preparation of diluted (4-5%) acetic acid and its storage. A standardized protocol for training, teaching material (easy to understand in the local language) for trainees, supervision and reinforcement by intermittent and supplementary training to check the quality of their observation, a standard protocol for preparation dilute acetic acid and its storage and a standard good light source (equivalent to day light) are needed to minimize the variation in sensitivity and specificity of VIA in community settings.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2014.11a
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• pp.248-251
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• 2014

We develop the signal processing method for implementing the human perceptual variant on frequency and space. The human visual perceptual sensitivity varies as frequency components and the human perceivable resolution diminishes as the distances further from the eye-focused point. For realizing the frequency sensitivity, we developed the signal direction adaptive multiband energy scaling method to weight the frequency components. The low-pass filtering is designed on the developed energy scaling method for diminishing perceivable resolutions as the deviated distance from the eye-focused point. The developed method not only enhances the frequency components of image signals at the eye-focused region but also smoothes non-perceivable detailed image signals at non-focused regions. The proposed method is verified by the subjective and objective evaluations that it can improve human perceptual visual quality.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.48 no.3
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• pp.294-303
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• 1999

To improve the visual servoing performance, several strategies were proposed in the past such as redundant feature points, using a point with different height and weighted selection of image features. The performance of these visual servoing methods depends on the configuration between the camera and object. And redundant feature points require much computation efforts. This paper proposes the visual servoing method based on the disturbance obsever, which compensates the upper off-diagonal component of image feature jacobian to be the null. The performance indices such as sensitivity for a measure of richness, sensitivity of the control to noise, and comtrollability are shown to be improved when the image feature Jacobian is given as a block diagonal matrix. Computer simulations are carried out for a UUMA560 robot and show some results to verify the effectiveness of the proposed method.

• Proceedings of the KIEE Conference
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• 1999.07g
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• pp.3077-3079
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• 1999

A visual servoing method has been proposed based on disturbance observer to eliminate the effect of the off-diagonal component of image feature Jacobian, since performance indices such as measurement sensitivity of visual features, sensitivity of the control to noise and controllability could be improved when an image feature Jacobian was given as a block diagonal matrix. In this paper, experimental results of disturbance observer-based visual servoing are discussed where Samsung FARAMAN-ASl 6-axis industrial robot manipulator is employed. Also, the feature saturator is proposed to stabilized the disturbance observer loop by saturating the differential changes of the image features.

• Journal of Korean Ophthalmic Optics Society
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• v.20 no.4
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• pp.477-484
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• 2015

Purpose: This study was investigated to evaluate the effect of the variation of the face form angle(FFA) of spectacle frame on the visual acuity and the visual function. Methods: The visual acuity, the contrast sensitivity, the stereopsis, and the phoria were measured with the spectacle frame whose the FFA is at $5^{\circ}$ and $25^{\circ}$ and the surveys were conducted on subjective symptoms. Here, 30 adults (14 men and 16 women, average age:$25.46{\pm}3.9$), who did not have ocular diseases and were fully corrected in case of having had refractive error, were to act as experimental subjects for this measurement. Results: The visual acuity and the contrast sensitivity was decreased and the phoria was tended to increase to the esophoria direction at the FFA $25^{\circ}$ than at the FFA $5^{\circ}$. The stereopsis was significantly reduced at the FFA $25^{\circ}$ than at the FFA $5^{\circ}$. Also when the FFA was larger, the higher the degree of refractive error was, the more the increase of the subjective symptoms such as being blurred characters, being disturbed head, and having sore eyes was, which reveals a statistically significant correlation between them. Conclusions: If the FFA increases, the visual acuity, the contrast sensitivity and the stereopsis was found to decrease and the phoria to increase to the esophoria direction. Therefore it shows that the variation of the FFA of spectacle frame can influence the visual acuity and the visual function.

• Journal of Korean Ophthalmic Optics Society
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• v.14 no.1
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• pp.39-45
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• 2009

Purpose: The purpose of this study is to compare the visual performance by contrast sensitivity (CS) and disability glare (DG) in low astigmatic eyes corrected with toric soft lenses and other optical corrections. Methods: Twenty university students with myopia (-1.00 to -6.50D Sph. with astigmatism up to 1.50 cyl) were enrolled and corrected by five different methods: 1) soft toric lenses; 2) spherical soft contact lenses; 3) RGP lenses; 4) best spectacle corrected visual acuity; 5) spherical equivalent spectacles. All subjects had corrected vision acuity of 20/20 or better. Contrast sensitivity and disability glare were measured using the OPTEC 6500 contrast sensitivity view-in tester included the EyeView Functional Vision Analysis software at photopic or mesopic conditions with glare. Results: At photopic condition, best corrected spectacle wearers had the highest monocular contrast sensitivity at all spatial frequency followed by soft toric lenses, RGP lenses, spherical equivalent spectacles, and spherical soft contact lenses. However, all of them were in normal contrast sensitivity value at photopic condition. At mesopic condition with glare, toric soft lenses were the highest and followed by RGP lenses, spherical equivalent spectacles, best spectacle corrected visual acuity and spherical soft contact lenses. It was observed that spherical soft contact lens wearers demonstrated lower range than normal contrast sensitivity value at mesopic condition with glare. Conclusion: Toric soft lenses gave better visual performance than spherical soft lenses in low astigmatic eyes. Subjects requiring the use of contact lenses under mesophic conditions could benefit from toric soft lenses.

• Science of Emotion and Sensibility
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• v.18 no.2
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• pp.3-18
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• 2015

Numerosity perception is considered as an innate ability of human being where its sensivitiy may widely vary across each individual person. The present study explored the relationship between visual working memory (VWM), visual search efficiency, and numerosity sensitivity. To accomplish this, we calculated each participant's K-value from change detection performance representing one's storage capacity in VWM, slopes of search RTs representing the search efficiency, and discrimination sensitivity for a quantity difference across two sets of dot arrays representing the numerosity sensitivity. The correlational analysis across the measurements revealed that participants with a high VWM capacity better discriminated the numerosity difference in the arrays when the spatial information in the two dot arrays was preserved. In contrast, the participants with high search efficiency discriminated better the difference in the arrays when the spatial information in the arrays was not preserved. The results indicate high VWM-capacity individuals were presumably able to use a strategy of storing the dot arrays by grouping them into a smaller pattern of dot arrays while high search-efficiency individuals were able to use a strategy of rapidly switching their focused attention across the dots in the arrays to count each individual dot. These in sum suggest that individual differences in numerosity sensitivity rely on one's working memory capacity as well as their efficient use of switching focused attention.