• Korean Journal of Optics and Photonics
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• v.11 no.2
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• pp.85-90
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• 2000

The image quality of CRT displays is descnbed by the physical characteristics such as luminance, contrast, address ability, viewing distance, and so on. However, the final evaluation of rmage quality is deteITIlllled by not phYSICal data, but subjective perceived Image quality. Therefore the correlation is compared the score of subjective image qualIty accompli~hed by several persons with calculated SQRI (SQuate Root Integral) value uSlllg 4 kInds of CRT monitors. And the influence of tile physical chatac1eristics for subjective Image quality is analyzed on the basis of the validity of SQRI method as a metric for the evaluation of subjective image quality. ality.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2012.07a
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• pp.392-393
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• 2012

영상에서의 화질 평가는 학술적으로나 산업적으로나 중요한 문제이지만 지금까지 주로 쓰여온 PSNR 과 같은 방법은 실제 사람이 인식하는 평가에 잘 부합하지 못하는 문제점이 있었다. 본 논문에서는 모든 밝기 영역에서 영상을 평가할 수 있는 HDR-VDP2 와 주목도 지도를 결합하여 범용적으로 사용이 가능하며 성능도 뛰어난 화질 측정 방법을 제시하고, 다양한 주목도 지도에 대하여 그 성능과 화질 평가 성능 사이의 관계를 살펴본다. 구현에는 주목도 지도를 가중치로 사용함으로써 간단하게 더 좋은 성능의 화질 평가 시스템을 만들었고 이를 실험으로 보였다. 또한 주목도 지도의 성능과 화질 평가 시스템의 성능 사이에는 약한 양의 상관관계가 있는 것으로 나타났는데 주목도 지도와 함께 구조적 특징점들의 정보를 성능 평가 시스템에 포함시키면 더 좋은 결과를 얻을 것으로 기대된다.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2008.11a
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• pp.185-188
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• 2008

영상의 화질을 평가하는 방법은 어떤 정보를 기준으로 평가하느냐에 따라서 전체 기준법 (Full Reference), 부분기준법 (Reduced Reference) 그리고 무기준법 (No Reference)으로 나눌 수 있다. 이중 무기준법은 수신 영상만을 가지고 측정하기 때문에, 다른 방법보다 활용범위가 넓다. 또한, 최근 사람의 눈의 특성을 고려한 인지적(Perceptual)화질평가 방법이 많이 논의되어, 사람이 실제 보고 느끼는 바를 객관화 시키는 방법이 개발되어 왔다. 이들 화질평가 방법들에 대해 많은 연구가 수행되고 있으며, 국제기구들을 통하여 이들 지표들에 대한 표준화가 진행되고 있다. 본 논문에서는 휘도, 색차의 분포도를 분석하여 원본의 화질을 예측하는 방법을 통해서, 기존 무기준법의 정확도를 높이고자 한다. 영상신호의 양자화나 부호화로 인해 임계값을 벗어나는 값들이 생기게 되며, 이 값을 휘도, 색차의 분포도 분석으로 예측하여 화질평가를 수행하게 된다. 실험 결과 제안된 방법의 상관도는 다른 방법보다 높은 것으로 나타났다.

• Proceedings of the Korea Information Processing Society Conference
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• 2004.11a
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• pp.225-228
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• 2004

본 논문은 이동통신을 위한 입력영상을 취득할 때 사용되는 웨이블릿, 소벨 필터 기반의 화질평가 방식을 다양한 실험을 통해 검증하고 영상과 전처리 기법에 따라 주관적 평가에 근접한 화질평가방식을 제안한다.

• Journal of Broadcast Engineering
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• v.14 no.4
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• pp.387-396
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• 2009

No-Reference video-quality assessments are divided into two kinds of metrics based on decoding pixel domain or the bitstream one. Traditional full-/reduced- reference methods have difficulty to be deployed as realtime video transmission because it has problems of additional data, complexity, and assessment accuracy. This paper presents simple and highly accurate no-reference video-quality assessment in realtime video transmission. Our proposed method uses quantization parameter, motion vector, and information of transmission error. To evaluate performance of the proposed algorithm, we perform subjective test of video quality with the ITU-T P.910 Absolute Category Rating(ACR) method and compare our proposed algorithm with the subjective quality assessment method. Experimental results show the proposed quality metric has a high correlation (85%) in terms of subjective quality assessment.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.41 no.6
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• pp.81-88
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• 2004

In this paper, we propose a new objective quality assessment method considering the human visual perception characteristics. A subjective quality assessment is obtained by the response of the receptive field in the primary visual cortex and a human's eye can't focus on all of the visual range in a moment. Take advantage of two facts above, we apply Gabor wavelet transform which is well fit the receptive field in the cortex, to divided constant sized subblocks. Then a local distortion of the subblocks and a global distortion for the entire image are calculated in order. The proposed method has been evaluated using video test sequences provided by the Video Quality Experts Group (VQEG). The experimental results show that good correlation with human perception is obtained using the proposed metric, which is what we called GPSNR.

• Journal of the Institute of Electronics and Information Engineers
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• v.51 no.7
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• pp.180-189
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• 2014

Display quality assessment has been a long standing issue due to the diversity of display devices and the rapid growth of display technology. The conventional display quality assessment methods are mostly those methods which evaluate qualities of a display by measuring physical quantities, but the results from the methods are not equal to the perceived results which are acquired with subjective experiments. Thus, we need to solve the above contrariety as well as establish the quantitative correlation between physical and perceived results. This paper proposes the systematic method of evaluating relative perceived qualities among various display devices and quantifies these relative perceived qualities. The proposed method is based on Analytic Network Process(ANP), which is one of the most popular decision making methods in the business administration field. We also adopted three evaluation criteria, which consist of color, shape and depth, in order to reflect the human visual system and chose eight sub-criteria related to display characteristics via question investigation. We carried out a subjective experiment and the proposed method which evaluated perceived qualities of two display devices(TFT-LCD, OLED) in order to prove the similarity between their results. As a result, it is proved that the order relationship between perceived qualities was the same as the order of results got through the subjective experiment.

• Proceedings of the Korean Society for Emotion and Sensibility Conference
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• 2000.04a
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• pp.412-416
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• 2000

본 연구는 TV 화질 설정치를 조절하여 제시된 실제 TV 화질에 대한 감성 평가를 실시하여, TV 화질에 대한 심리적 차원이 어떻게 구성되어 있는지를 알아보고, 또한 TV 최적 화질을 결정하는 감성요인을 규명하기 위해 수행되었다. 피험자들은 다섯가지 TV 화질 변인 (밝기, 명암, 선명도, 색상, 색농도) 각각을 각각 네 수준으로 조절하여 제시하는 네 종류의 자극 (인물, 실내, 정물, 풍경)을 본 후, 각 화질에 대한 감성을 평가하였다. 그 결과 TV 화질에 대한 감성 차원은 "깔끔함"과 "화려함" 두 주된 요인으로 구분되었다. 그리고 가장 만족스러운 TV 화질을 결정하는 감성 요인으로는 "자연스럽다", "침울하다-산뜻하다", "거칠다-매끄럽다" 순으로 나타났다. 네 자극중에서 TV 최적 화질을 결정하는 공통적인 요인은 "자연스럽다"였다.로 나타났다. 네 자극중에서 TV 최적 화질을 결정하는 공통적인 요인은 "자연스럽다"였다.다"였다.t;였다.

• Journal of the Korean Society of Radiology
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• v.2 no.2
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• pp.5-10
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• 2008

Most of the diagnostic medical radiography are rapidly replaced by digital imaging systems recently. Although with the current transition of analog to digital most of the exposure conditions and parameters are still on the basis of film-screen analog system. Moreover the evaluation of acquired digital radiographic image is not fulfilled normally because of the difficulties in handling the digital raw data. The user friendly windows program for the evaluations of digital radiographic image was developed on the MatLab platform. The program has functions for the calculation of the contrast profile, NPS(noise power spectrum), MTF(modulation transfer function), and NEQ(noise equivalent quanta).

• The KIPS Transactions:PartB
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• v.15B no.5
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• pp.383-390
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• 2008

Block based transform coding is most popular approach for image and video compression. However it suffers from severe quality degradation especially from blocking artifacts. The subjective quality degradation caused by such blocking artifacts in general does not agree well with an objecive quality measurement such as PSNR. Hence new quality evaluation technique is necessary. We propose a new image quality assessment method by measuring blocking artifacts for block based transform coded images. In order to characterize blocking artifacts, proposed method utilizes the facts that, blocking artifacts, when occur, have different pixel values along the block boundaries and such differences usually continuously span along the whole boundaries. This method does not require the original uncompressed image. It operates on single block boundary and quantifies the amount of blocking artifacts on it. Experiments on various compressed images various bitrates show that proposed quantitative measure of blocking artifacts matches well with the subjective quality of them judged by human visual system.