• Korean Journal of Cognitive Science
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• v.14 no.3
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• pp.51-59
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• 2003

Various perceptual distortions in spatial vision occur during eye movements. Most of the studies on perceptual distortion have focused on the conjunctive eye movements. Recently, Li, Kham, Kim & Yoon (2002) reported that subjects experienced perceptual distortion of 3D slant of an object defined by the spatiotemproal pattern of occlusion. The present research examined whether the subjects experienced the same perceptual distortion in the target object whose luminance is different from that of background. It also examined the effect of the reference on the perceptual distortion of 3D slant of an object.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.21 no.3
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• pp.587-599
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• 1996

In general fractal imge compression, each range block is approximated by a contractive transform of the matching domain block under the mean squared error criterion. In this paper, a distortion measure reflecting the properties of human visual system is defined and applied to a fractal image compression. the perceptual distortion measure is obtained by multiplying the mean square error and the noise sensitivity modeled by using the background brightness and spatial masking. In order to compare the performance of the mean squared error and perceptual distortion measure, a simulation is carried out by using the 512*512 Lena and papper gray image. Compared to the results, 6%-10% compression ratio improvements under improvements under the same image quality are achieved in the perceptual distortion measure.

• Journal of Broadcast Engineering
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• v.14 no.2
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• pp.210-218
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• 2009

The 3D shape as well as the depth of an object presented on a 3D display is perceptually distorted depending on viewing distance. It is quite undesirable that different observers perceive different depth and shape from an object displayed on a 3D monitor. To resolve the problem of perceptual distortion of 3D depth and shape, the degree of the distortion should be measured appropriately. As a basis for resolving these problems, the present research suggests an instrument for measuring the degree of the perceptual distortion of 3D depth and shape.

• Phonetics and Speech Sciences
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• v.6 no.1
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• pp.85-93
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• 2014

This paper investigated the effects of frequency band limitation on perceptual characteristics of Korean vowels. Monosyllabic speech (144 syllables of CV type, 56 syllables of VC type, 8 syllables of V type) produced by two announcers were low- and high-pass filtered with cutoff frequencies ranging from 300 to 5000 Hz. Six listeners with normal hearing performed perception tests by types of filter and cutoff frequencies. We reported phoneme recognition rates and types of perception error of band-limited Korean vowels to examine how frequency distortion in the process of speech transmission affect listener's perception.

• The Research Journal of the Costume Culture
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• v.7 no.5
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• pp.68-79
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• 1999

The purposes of the study, based on the social comparison theory, were 1) to examine the body image and the body distortion of the late adolescent through the attitudinal and perceptual measurement of the body image and to examine the self-esteem, 2) to examine the difference of the clothing behaviors depending on the level of the body image, the body distortion and the self-esteem, 3) to examine the difference in the clothing behavior, the body image and the self-esteem according to sex. The sampling method was a convenient sampling and the subjects were 137 undergraduate students in Chungnam national University. The results of this study were as follows : The results of analysing the factors to the response of attitudinal body image emerged three factors (appearance interest, weight concern, and body satisfaction). The results of analysing the response of the clothing behavior showed four factors (fashion interest, psychological dependence of clothing, conformity to clothing, and exhibitionism of clothing). The positive group to the body image showed more interest in the fashion and had the tendency of depending on the clothing psychologically, and also showed that the group revealed much exhibitive attitude by using the clothing. The group of perceiving the face rather correctly tends to do the conformity behaviors, but the group distorting the shoulder width wider than tends to reveal more conformity behaviors. The group with the higher self-esteem had little interested in the fashion and also did the conformity behaviors slightly.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2011.07a
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• pp.122-125
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• 2011

In real environment, background noise exists everywhere and degrades the performance of system. To reduce this distortion, a speech enhancement algorithm can be very useful and variety methods have been proposed. In this paper, we propose a postfilter to improve the performance of optimally modified log-spectral amplitude (OM-LSA) estimator. Proposed algorithm uses the formant postfilter to minimize perceptual distortion caused by background noise. We adjust an emphasizing parameter which is varied by spectral flatness and first reflection coefficient. The performance of the proposed algorithm is evaluated by measuring the log-spectral distance (LSD) and the perceptual evaluation of speech quality (PESQ) score. The test results show the improvement of proposed algorithm compared to conventional OM-LSA.

• 제어로봇시스템학회:학술대회논문집
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• 2005.06a
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• pp.225-228
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• 2005

According to a popularization of the Internet and digital lifestyle, digital watermarks have been proposed for protection of copyrighted multimedia content. In blind watermark detection, which an original image is not provided, robustness against geometric distortion and compression remains challenging. In this paper, we propose a new perceptual blind discrete wavelet transform - discrete Fourier transform (DWT-DFT) composite watermarking scheme that is robust against both general linear transform and JPEG compression. This algorithm constructs an image-dependent watermark in the most significant DWT coefficients, which is determined by using a hierarchical tree structure. Strength of watermark is determined from a just-noticeable difference (JND) profile of a perceptual model. Furthermore, a desired template is inserted into DFT domain of the watermarked image. In new manner, a cross-ratio of four collinear points is used for detecting the template. Experimental results have showed that the proposed scheme is robust against general linear distortion, JPEG compression and various general kinds of attacks in the Stirmark 3.1 watermark evaluation tool.

• Phonetics and Speech Sciences
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• v.6 no.1
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• pp.95-101
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• 2014

This paper investigated the effects of frequency band limitation on perceptual characteristics of Korean consonants. Monosyllabic speech (144 syllables of CV type, 56 syllables of VC type, 8 syllables of V type) produced by two announcers were low- and high-pass filtered with cutoff frequencies ranging from 300 to 5000 Hz. Six listeners with normal hearing performed perception test by types of filter and cutoff frequencies. We reported phoneme recognition rates and types of perception error of band-limited Korean consonants to examine how frequency distortion in the process of speech transmission affect listener's perception. The results showed that recognition rates varied with the following factors: position in a syllable, manner of articulation, place of articulation, and phonation types. Consonants in the final position were stronger to the frequency band limitation than those in the initial position. Fricatives and Affricates are stronger than stops. Fortis consonants were less stronger than their lenis or aspirated counterparts. Types of perception error also varied depending on such factors as consonant's place of articulation: In case of bilabial stops, they were perceived as alveolar stops with while in cases of alveolar and velar stops, there were changes in phonation types without any change in the place of articulation.

• Journal of the Korean Institute of Telematics and Electronics B
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• v.32B no.1
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• pp.64-72
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• 1995

We propose a new image coding method which takes into account both statistical redundancy and perceptual irrelevancy of the DCT coefficients so as to provide a high quality of the reconstructed images with a reduced transmission bit rate First, a block of DCT coefficients are decomposed into 16 subvectors so as for a subvector to convey key information about one of the low-pass or the dirctional filtered images. Then, the most significant subvector is selected as the principal edge of the block and then vector quantized. After that, the residuals of the block are computed and then sequentially quantized through aforementioned procedure until the quantization distortion is smaller than the target distortion. The proposed scheme is good at encoding images with a variety of transmission bit rates, especially at very low bit rate coding. In addition, it is another benifit of the proposed scheme that an image can be quantized with a wide range of the transmission bit rates by simply adapting the stopping criterion of the sequential vector quantizer according to the target distortion of the reconstructed image.

• Korean Journal of Cognitive Science
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• v.16 no.3
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• pp.175-188
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• 2005

Recently, Li, Brenner, Cornelissen and Kim (2002) reported that 2D shape perception during pursuit eye movement just reflected the retinal image, and this result implies that the visual system ignored the extra-retinal information. In reality, however, we usually do not experience the perceptual distottion of 2D shape during pursuit eye movement. One Possibility is that the visual system night exploit the fact that the relative location between objects on retinal image is constantly maintained even during pursuit eye movement. The present research examined this possibility. Interestingly, perceptual distortion of 2D shape was observed even in the presence of reference, however, the amount of distortion decreased compared to when the reference does not exist. The distance between the reference and the target affected the perceptual distortion. These results imply that reference information is used in 2D shape perception during pursuit eye movement but it cannot completely explain the stable and accurate representation of 2D shape perception during pursuit eye movement.