• Journal of the Optical Society of Korea
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• v.18 no.6
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• pp.809-817
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• 2014

The loss in contrast-discrimination ability of the human visual system under high ambient illumination level can cause image quality degradation in mobile phones. In this paper, we propose a perceived contrast compensation method by processing the original displayed image. With consideration that the perceived contrast significantly varies across the image, this method extracts the local band contrast from the original image; it then compensates these contrast components to counteract the perceived contrast degradation. Experimental results demonstrate that this method can maintain most contrast details even in high ambient illumination levels.

• Journal of the Optical Society of Korea
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• v.18 no.1
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• pp.89-94
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• 2014

It is established that the perceived image contrast is affected by surround luminance. In order to get the same perceived image contrast, the optimum surround compensation ratios for those surround conditions is needed. Much research has been performed for dark, dim, and average surrounds. In this study, a wide range of surround luminance from dark up to $2087cd/m^2$ was considered. Using magnitude estimation method, the change in perceived brightness of six test stimuli was measured under seven surround conditions; dark, dim, 2 levels of average, bright, and 2 levels of over-bright surrounds. To drive the perceived image contrast from the perceived brightness, two different definitions of contrast were tested. Their calculated results were compared with the visual data of our previous work. And to conclude, the perceived contrast compensation ratios were 1:1.11:1.2 for average, dim and dark surrounds. These were close to CIECAM02 model (1:1.17:1.31). Besides, for average, bright, over-bright1 and over-bright2 surrounds the ratios 1:1.17:1.42:1.69 were determined. For intermediate or more extreme surround conditions, the compensation ratio was obtained from the linear interpolation or extrapolation.

• 한국정보디스플레이학회:학술대회논문집
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• 2009.10a
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• pp.1160-1163
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• 2009

Many researches showed that perceived image contrast increases as the relative surround luminance increases. However, most experiments were conducted under limited surround conditions. In this research, a psychophysical experiment was conducted to investigate the change in perceived image contrast under wide range of surround luminance up to 1820 cd/$m^2$. A large area illuminator was used as a backlight. It consists of 23 dimmable fluorescent lamps and a sheet of diffuser. The luminance could be adjusted to 7 different surround ratios: 0, 0.3, 0.56, 0.96, 2.24, 5.81, and 9.99. Results showed that perceived image contrast changes as a typical band-pass shape and the maximum contrast is found near $S_R$=1.

• 한국정보디스플레이학회:학술대회논문집
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• 2008.10a
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• pp.745-748
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• 2008

The theory of Bartleson and Breneman that the perceived image contrast changes with surround luminance (the lighter surround provides higher contrast) was tested an over bright condition($8500d/m^2$). Contrarily to the Bartleson and Breneman's results, we observed the fact that perceived constrast was decreased when surround huminance increased from dark to over bright through two sets of psychophysical experiments based upon both uniform gray patches and complex color images.

• Journal of Korean Society for Quality Management
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• v.44 no.3
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• pp.527-540
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• 2016

Purpose: The purpose of this study was to propose contrast metric which is based on the human visual perception and thus it can be used to improve the quality of digital images in many applications. Methods: Previous literatures are surveyed, and then the proposed method is modeled based on Human Visual System(HVS) such as multiscale property of the contrast sensitivity function (CSF), contrast constancy property (suprathreshold), color channel property. Furthermore, experiments using digital images are shown to prove the effectiveness of the method. Results: The results of this study are as follows; regarding the proposed contrast measure of complex images, it was found by experiments that HVS follows relatively well compared to the previous contrast measurement. Conclusion: This study shows the effectiveness on how to measure the contrast of complex images which follows human perception better than other methods.

• Journal of the Korean Society of Clothing and Textiles
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• v.30 no.4 s.152
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• pp.633-643
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• 2006

When women are exposed to images of other attractive women such as media models, it is known that many go through a social comparison process and a contrast effect occurs which results in unfavorable perception and attitudes toward the self. This paper suggests women's perception of control over their appearance as one of the factors that may moderate the contrast effect of a social comparison with attractive media models. An experiment with 211 women was conducted to examine the differential effect of viewing attractive models versus non-human images on the responses of women with high/low perceived control over appearance. A two(Stimuli Type: attractive-model image vs. non-human image) by two(Perceived Control over Appearance: High vs. Low) MANCOVA model was tested with physical appearance anxiety, self-esteem, and body satisfaction as dependent variables and appearance orientation, body mass index, age, years of schooling, ethnicity, and marital status as covariates. A significant Perceived Control main effect on Physical Appearance Anxiety and Self-Esteem and a significant Stimuli Type by Perceived Control interaction effect on Physical Appearance Anxiety and Self-Esteem were found. Those who perceived high control over their appearance were more likely to have higher self-esteem and lower appearance anxiety. However, among those who saw attractive model's images, women perceived low appearance control showed less anxiety and higher body satisfaction than those perceived high appearance control.

• International journal of advanced smart convergence
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• v.11 no.4
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• pp.253-259
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• 2022

This study aims to investigate the antecedent of consumer personal preventive equipment purchase behaviour by extending the HBM model after the pandemic. Pandemic related studies have focused on the effect of perceived susceptibility and perceived severity on consumer preventive behaviour, little studies have investigated the antecedents of consumer perceived risk. This study filled the gaps in the previous studies. This study tested all proposed hypotheses among users who have purchase the self-preventive behaviour. In final 253 valid data were collected through online survey for statistics analysis. This study found that consumer's health consciousness significantly impacted consumer's perceived severity of COVID-19 and perceived risk. Perceived risk positively impacted consumer self-preventive equipment purchase intention. In contrast, perceived susceptibility did not significantly consumer perceived risk. Based on these results, the theoretical implication will be offered on the study of health-related studies and will be given insight for disease control center to effectively manage consumer self-preventive behaviour.

• Journal of the Korean Society of Clothing and Textiles
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• v.29 no.6
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• pp.825-836
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• 2005

The purpose of this research is to analyze the harmony of contrast coloration of the traditional Korean dress as the subject of the study for women's college students in Korea and America. The sense of harmonious coloration for 64 colorations was evaluated based on a yellow and a green Korean jackets, to be contrast colorization, by combining four different tones, vivid, light, dull, and dark tones in a purple and a blue skirt with a yellow jacket, a red and a purple skirt with a green jacket. We tried to make sure of the cultural difference by the distinction in the perception of women's college students. in Korea and America. The result of the study is as follows. In the contrast coloration of a yellow jacket with a purple and a blue skirt, Korean women students, generally, perceived that the coloration that skirt is more dark than jacket, dull and dark tone is harmonious. On the other hand, American women students perceived harmonious skirt tone is various depending on the jacket tones. In the coloration of a green jacket and a red skirt, the women students of two countries are in common that the coloration of a vivid skirt with a vivid, a dull, and a dark jacket are harmonious. However, Korean women students indicated that a light jacket with a dark tone skirt as a harmonious coloration. American women students evaluated that various tones of coloration as a harmonious coloration. In the coloration of a green jacket and a purple skirt, Korean women students perceived that the coloration is incompatible coloration. American women students perceived the coloration is congruous in the coloration of a dull and a dark tone jacket and skirt. In the response of the perception for 64 contrast coloration, Korean students evaluated 14 sets and American students judged 28 sets as harmonized colors. Therefore, it drew the conclusion that Korean students had the sense of harmonious coloration of more narrow range than American students. There was a difference between two cultures in the standard far contrast coloration.

• Journal of the Institute of Electronics and Information Engineers
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• v.52 no.2
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• pp.141-147
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• 2015

The contrast of a display is generally evaluated by using the ratio of the minimum luminance to the maximum luminance of the display. However, this contrast ratio is not matched with perceived contrast because it uses only physical characteristic of display without considering human perceptual characteristics. In this paper, the proposed contrast measure that considers perceptually discriminable brightness within the range of display brightness is suggested. First, the range between the minimum and maximum brightness of display in CIECAM02 color space is calculated to measure the length of perceived brightness for the display. Next, brightness ranges which are perceptually same at each brightness level are determined by applying Weber-Fechner ratio and then, the number of brightness values within each brightness range is counted. Finally, perceptually discriminable brightness is defined as the sum of ratio between the number of brightness values in each brightness range and the perceptual contrast length of the display. In the experiments, preference test using various displays with random brightness patches is performed to evaluate perceived contrast. As a result, the proposed measure is more consistent with human perception than the previous contrast measures.

• Journal of the Korean Institute of Telematics and Electronics B
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• v.29B no.11
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• pp.93-101
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• 1992

HVS based transform coding techniques for still images take the lowest spatial frequency and luminance contrast sensitivity as the most crucial factors in determining the image quality perceived by human eye. Only the frequency weighting has been main issue. The proposed Weighted Discrete Cosine Transform (WDCT) has the lowest frequency of about 4 [cyc/deg] in 8$\times$8 subblock with the contrast-weighted DC coefficient. The error criteria have been rederived to adapt the contrast weighting for performance evaluation. The proposed scheme has produced higher quality images compared to the unweighted and other schemes.