• Journal of Broadcast Engineering
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• v.18 no.3
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• pp.416-424
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• 2013

Recently, efforts have been made to develop international standards related to 3DTV quality assessment underway in International Telecommunication Union and Video Quality Experts Group. Unlike conventional 2D displays, there are several types of 3D display monitors: passive glasses, active glasses and auto-stereoscopic. In this paper, we performed subjective video quality tests using various 3D display monitors, in order to examine whether these display monitors can produce consistent perceptual video quality scores for processed video sequences. The experimental results show that the subjective scores of those 3D monitors are highly correlated and it appears that similar subjective scores will be obtained even when different types of 3D displays are used.

• Journal of Digital Convergence
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• v.13 no.9
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• pp.351-359
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• 2015

This convergence study analyzed the effectiveness of digital radiography system of copper(Cu) filter in the added filtration for the removal of lower energy radiation through dose and image evaluation. We were analyzed from April to June 2015 result of the examination. Cu filter was applied to each non, 0.1, 0.2, 0.3 mm according to change of kV and mAs and doses were evaluated. Image quality was evaluated by PSNR, MAE, MSE, CNR, SNR and qualitative analysis was performed by seven items for resolution and contrast from chest x-ray criteria of national cancer checkup. The absorbed doses with Cu were lowered by 16-88 % than non-filter but the gaps decreased as kV increased. PSNR were over 30 dB and all significant and CNR and SNR were superior with non-filter but in the qualitative analysis, there were different statistical significant according to each item. The score of 0.1 mm filter was high at pulmonary blood vessel observation and in the 0.3 mm Cu, there were no statistical signigicant except high density and full of air portion. Cu filter can improve image quality with lower radiation dose using better radiation quality and correction power at digital radiography system.

• Journal of Broadcast Engineering
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• v.16 no.3
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• pp.552-560
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• 2011

In this paper, a new no-reference sharpness measure using frequency domain coefficients is proposed. Although most existing sharpness measures used pixel intensity to compute the blur degree, the proposed sharpness measure computes the sharpness using frequency coefficients. To assess the perceived sharpness of a given image, the image is re-blurred by a Gaussian low pass filter and a new quality measure function was defined using the frequency domain coefficients of the given image and the re-blurred image. To evaluate the proposed algorithms, TID2008 quality assessment database was used. Experimental results show that the proposed quality assessment method showed high correlation with the subjective scores.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.36 no.4B
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• pp.314-321
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• 2011

There have been considerable standardization works to measure subjective video quality. However, these standardization methods are based on the situation where they have original or reference video sequences, and measure the video quality by looking the sequence during short time duration, e.g. 10 seconds. Since people's TV watching time durations in IPTV services are very long (e.g. more than 30 minutes), the quality measurements by the standards are not practical. In this paper, we analyze the effect of video quality rating period to MOS (Mean Opinion Score), and suggest a proper rating duration of subjective video quality for IPTV services.

• Science of Emotion and Sensibility
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• v.16 no.3
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• pp.373-386
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• 2013

In this research, we specify the image consumers' preferred image quality ranges based on objective image quality evaluation factors and follow a method which measures preference of the natural image scenes. In other words, according to No-Reference, we select dynamic range, color, and contrast as factors of image quality measurements. For collecting sample images, we choose the preferred 200 landscapes which have over 30 recommendations by image consumers on the internet photo gallery. According to the scores of three objective factors of image quality measurements, the final expected score which means the image quality preference is measured and its total score is 100 points. In the main test, the actual image sample shows dynamic range 10 stop, LAB mean value L:54.7, A:2.96, B:-15.84, and RSC contrast 376.9. Total 200 image samples' normal distribution z value represents in dynamic range 0.21, LAB mean value L:0.15, A:0.38, B:0.13, and RSC contrast 0.08. In the standard normal distribution table, we can convert the z value as a percentage; dynamic range is 8.32%, LAB mean value is L:5.96%, A:14.8%, B:5.17%, and RSC contrast is 3.19%. And then, we convert the percentage values into the scores of 100; dynamic range is 91.68, LAB mean value is 91.36, and RSC contrast is 96.81. Therefore, we can conclude that the sample image's total mean score is 94.99 based on three objective image quality factors. Throughout our proposed image quality assessment model, we can measure the preference value of natural scenes. Also, we can specify the preferred image quality representation ranges and measure the expected image quality preference.

• Proceedings of the Korean Society for Emotion and Sensibility Conference
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• 2009.11a
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• pp.107-110
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• 2009

본 연구에서는 동영상 자극이 제시되었을 때 시각적으로 느껴지는 감성을 자율신경계 반응, 동공반응 그리고 주관 설문으로 평가하였다. 20~27세 사이의 대학생 남녀 20명이 실험에 참여 하였고 뉴스, 다큐멘터리1, 다큐멘터리2, 사랑, 스포츠 그리고 전쟁의 6가지 장르의 동영상에서 Gamma, Hue, Lightness 그리고 Saturation의 4가지 화질변수가 변경된 영상을 시각자극으로 제시하였다. 장르를 다르게 한 실험이 총 6회 진행되었으며 장르별로 기본영상 1개와 화질변수가 변경된 영상 16개가 무작위 순서로 제시되었다. 1회 실험이 진행되는 약 14분 동안 PPG, SKT 그리고 GSR 센서를 착용하여 생리 반응을 측정하였고 눈 영상을 기록하여 동공 반응을 측정하였다. 시각자극에 대한 주관적 평가를 위해 1~7점 척도의 불쾌도, 긴장도 그리고 피로도 항목의 설문을 실시하였다. 생리반응, 동공반응 그리고 주관설문 결과를 화질변수 별로 나누고 일원배치 분산분석을 실시하여 차이가 있는지를 확인하였다. 그 결과 시각 감성이 어떤 화질변수에 의해 유발되는지 확인할 수 있었다.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2013.11a
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• pp.128-130
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• 2013

양안식 3DTV 비디오의 효율적인 압축을 위해 다양한 기술들이 연구되었으며, 그 중 좌우영상으로 상이한 해상도의 영상을 사용하는 비대칭 양안식 영상은 인간의 시각시스템이 상이한 해상도의 양안식 양상을 높은 쪽 영상의 품질에 가깝게 인지하는 특성을 이용한 대표적인 비트레이트를 절감 방식이다. 이에 다양한 연구에서 좌우해상도 차이에 따른 화질 저하 정도를 측정하려는 시도가 이루어졌으나, 기존 연구에서는 적정 시청거리를 고려하지 않고 좌우 영상의 크기만을 고려하여 실험하였으며 따라서 각 연구별로 상이한 실험 결과가 도출되었다. 본 연구에서는 인간의 시각 시스템을 고려하여 적정 시청거리를 계산하고, 이에 따라 좌우영상 비율 별 화질평가를 수행하였다. 특히 본 연구에서는 좌영상을 IID급 방송콘텐츠로 가정하고, 우영상을 모바일 방송콘텐츠로 가정함으로써, 실험 결과의 방송 서비스 활용가능성을 높였다.

• Korean Journal of Optics and Photonics
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• v.9 no.3
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• pp.205-211
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• 1998

The MTF(modulation transfer function) measuring system with a linear CCD(charge coupled-device) was constructed to cvaluate a color CRT(catode ray tube). The measured MTF values were corrected by considering the spectral response and the pixel sizes of CCD. The effects of a spot size, video bandwidth, pitch of shadow mask holes, display luminance, and ambient illumination on image quality were studied. The uniformity of resolution and the contrast Ioss by ambient light of the color CRT monitor were measured, and the results were analyzed by MTFA(modulation threshold area).

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2006.11a
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• pp.27-30
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• 2006

본 논문은 디지털 모바일 비디오에 대한 객관적 화질 평가 방법을 제안한다. 본 논문에서 제시하는 화질 평가 방법은 경계 영역을 구한 뒤, 그 주변 영역에서의 에러 값에 근거한 경계영역 특징과 영상 압축 코덱에 의하여 발생하는 블로킹 효과를 측정함으로써 주관적 화질을 객관화 하였다. 제안한 알고리듬의 성능 평가를 위하여 Mean Opinion Score (MOS)값과 기존의 방법/제안한 방법의 결과를 비교하였다. 본 논문에서는, 인간 시각에 의한 MOS값과의 상관도가 제안한 방법이 기존의 방법에 비하여 비교적 큼을 보였다.

• Journal of radiological science and technology
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• v.40 no.3
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• pp.393-400
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• 2017

The purpose of this study is to suggest a method to reduce the dose by Analyzing the dose area product (DAP) and image quality according to the change of tube current using NEMA Phantom. The spatial resolution and low contrast resolution were used as evaluation criteria in addition to signal to noise ratio (SNR) and contrast to noise ratio (CNR), which are important image quality parameters of intervention. Tube voltage was fixed at 80 kVp and the amount of tube current was changed to 20, 30, 40, and 50 mAs, and the dose area product and image quality were compared and analyzed. As a result, the dose area product increased from $1066mGycm^2$ to $6160mGycm^2$ to 6 times as the condition increased, while the spatial resolution and low contrast resolution were higher than 20 mAs and 30 mAs, Spatial resolution and low contrast resolution were observed below the evaluation criteria. In addition, the SNR and CNR increased up to 30 mAs, slightly increased at 40 mAs, but not significantly different from the previous one, and decreased at 50 mAs. As a result, the exposure dose significantly increased due to overexposure of the test conditions and the image quality deteriorated in all areas of spatial resolution, low contrast resolution, SNR and CNR.