• 품질경영학회지
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• 제44권3호
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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.

• 대한공간정보학회지
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• 제17권3호
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• pp.33-40
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• 2009

본 연구에서는 모자이크 영상에 대하여 정량적인 품질평가지수에 대한 적용 가능성을 제시하였다. 우선, 영상 품질평가를 위해 접합영상의 접합선을 이용한 연속성 평가와 색상을 이용한 유사성(similarity) 및 대비(contrast)를 이용하여 품질평가지수를 산정하였다. 선정된 품질평가 항목을 기반으로 최종적인 품질평가지수를 산정하여 실험자에 의한 주관적 평가와의 비교, 검증을 수행하였다. 그 결과 정량적 품질평가지수가 주관적 평가지수와 유사한 결과를 나타냄으로써 제시한 영상 품질평가지수를 이용하여 제작된 모자이크 영상에 대한 정량적이고 객관적인 모자이크 영상의 품질평가가 가능하다는 것을 보여주었다.

• Journal of Multimedia Information System
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• 제8권2호
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• pp.93-100
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• 2021

Under the time-varying temperature, the high-temperature radiation of forgings and the change of reflection characteristics of oxide skin on the surface of forgings lead to the difficulty of obtaining images to truly reflect the geometric characteristics of forgings. It is urgent to study the clear and reliable acquisition method of hot forging feature image under time-varying temperature to meet the requirements of visual measurement of hot geometric parameters of forgings. Based on this, this chapter first puts forward the quality evaluation method of forging feature image, which provides guarantee for the accurate evaluation of feature image quality. Furthermore, the factors that affect the image quality, such as the radiation characteristics of forgings and the photographic characteristics of cameras, are analyzed, and the imaging spectrum which can effectively suppress the radiation intensity of forgings is determined. Finally, aiming at the problem that the quality of image acquisition is difficult to guarantee due to the drastic change of radiation intensity of forgings under time-varying temperature, an image acquisition method based on minimum signal-to-noise ratio (SNR) based laser light intensity adaptation is proposed, which significantly improves the definition of feature light strips in forging images at high temperature, and finally realizes the clear acquisition of feature images of large-scale hot forging under time-varying temperature.

• 스마트미디어저널
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• 제8권4호
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• pp.64-71
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• 2019

The performance of an OMR (Optical Music Recognition) system is usually determined by the characterizing features of the input music score images. Low resolution is one of the main factors leading to degraded image quality. In this paper, we handle the low-resolution problem using the super-resolution technique. We propose the use of a deep neural network with instance normalization to improve the quality of music score images. We apply instance normalization which has proven to be beneficial in single image enhancement. It works better than batch normalization, which shows the effectiveness of shifting the mean and variance of deep features at the instance level. The proposed method provides an end-to-end mapping technique between the high and low-resolution images respectively. New images are then created, in which the resolution is four times higher than the resolution of the original images. Our model has been evaluated with the dataset "DeepScores" and shows that it outperforms other existing methods.

• 한국멀티미디어학회논문지
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• 제17권10호
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• pp.1205-1212
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• 2014

In this paper, we propose a high-quality stitching method of 3D multiple dental CT images. First, a weighted function is generated using the difference of two distance functions that calculate a distance from the nearest edge of an overlapped region to each position. And a blending ratio propagation function for two gradient vectors is parameterized by the difference and magnitude of gradient vectors that is also applied by the weighted function. When the blending ratio is propagated, an improved region growing scheme is proposed to decide the next position and calculate the blending intensity. The proposed method produces a high-quality stitching image. Our method removes the seam artifact caused by the mean intensity difference between images and vignetting effect. And it removes double edges caused by local misalignment. Experimental results showed that the proposed method produced high-quality stitching images for ten patients. Our stitching method could be usefully applied into the stitching of 3D or 2D multiple images.

• 한국컴퓨터정보학회논문지
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• 제14권3호
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• pp.75-82
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• 2009

영상의 비교는 PSNR을 이용하는 것이 일반적이다. PSNR이 35이상일 경우 육안으로 품질 차이를 구분하기 어렵다고 판단한다. 2006년 Lee 등은 원본 이미지 대신 원본 이미지의 MSB 비트열을 공개함으로써 소유권을 증명할 수 있는 프로토콜을 제안하면서, 두 이미지의 MSB 비트열의 유사도를 측정하기 위한 새로운 함수를 사용하였다. 이때의 유사도는 품질을 측정하기 위한 PSNR과는 그 의미가 조금 다른 측면이 있다. 즉, 원본 이미지로부터 생성된 대상 이미지가 현저히 떨어질 경우, PSNR은 매우 낮은 값을 보이지만 품질이 떨어지더라도 유사도 측면에서 본다면 두 영상의 상관관계는 매우 높게 나와야 할 것이다. 본 논문에서는 Lee 등이 제안한 MSB 비교 함수를 수정한 후, ICOR함수를 제안하였으며, 이 함수를 이용하여 두 이미지의 상관관계 판단에 적용할 수 있는지 분석하였다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제7권2호
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• pp.347-365
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• 2013

The performance of finger-vein recognition methods is limited by camera optical defocusing, the light-scattering effect of skin, and individual variations in the skin depth, density, and thickness of vascular patterns. Consequently, all of these factors may affect the image quality, but few studies have conducted quality assessments of finger-vein images. Therefore, we developed a new finger-vein recognition method based on image quality assessment. This research is novel compared with previous methods in four respects. First, the vertical cross-sectional profiles are extracted to detect the approximate positions of vein regions in a given finger-vein image. Second, the accurate positions of the vein regions are detected by checking the depth of the vein's profile using various depth thresholds. Third, the quality of the finger-vein image is measured by using the number of detected vein points in relation to the depth thresholds, which allows individual variations of vein density to be considered for quality assessment. Fourth, by assessing the quality of input finger-vein images, inferior-quality images are not used for recognition, thereby enhancing the accuracy of finger-vein recognition. Experiments confirmed that the performance of finger-vein recognition systems that incorporated the proposed quality assessment method was superior to that of previous methods.

• 한국멀티미디어학회논문지
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• 제21권9호
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• pp.1027-1034
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• 2018

CCTV has been known to possess high level of objectivity and utility. Hence, the government has recently focused on replacing low quality CCTV with higher quality ones or even by adding high resolution CCTV. However, converting all existing low-quality CCTV to high quality can be extremely costly. Furthermore, low quality videos prior to CCTV replacement are likely to be of poor quality and thus not utilized correctly. In order to solve these problems, this paper proposes a method to improve videos quality of images using SRGAN(Super Resolution Generative Advisory Networks). Through experiments, we have proven that it is possible to improve low quality CCTV videos clearly. For this experiment, a total of 4 types of CCTV videos were used and 10,000 images were sampled from each type. Those images could then be used for machine learning. The fact that the pre-process for machine learning has been done manually and the long time that required for machine learning seems to be complementary.

• ETRI Journal
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• 제38권6호
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• pp.1114-1123
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• 2016

Multi-view video plus depth (MVD) has been widely used owing to its effectiveness in three-dimensional data representation. Using MVD, color videos with only a limited number of real viewpoints are compressed and transmitted along with captured or estimated depth videos. Because the synthesized views are generated from decoded real views, their original reference views do not exist at either the transmitter or receiver. Therefore, it is challenging to define an efficient metric to evaluate the quality of synthesized images. We propose a novel metric-the reduced-reference quality metric. First, the effects of depth distortion on the quality of synthesized images are analyzed. We then employ the high correlation between the local depth distortions and local color characteristics of the decoded depth and color images, respectively, to achieve an efficient depth quality metric for each real view. Finally, the objective quality metric of the synthesized views is obtained by combining all the depth quality metrics obtained from the decoded real views. The experimental results show that the proposed quality metric correlates very well with full reference image and video quality metrics.

• 한국측량학회:학술대회논문집
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• 한국측량학회 2004년도 춘계학술발표회논문집
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• pp.285-290
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• 2004

Sensors of Landsat detect different objects with different waves, so the range of water quality conditions can be accurately checked, and their images can be displayed in colors. The present study was conducted to measure the degree of clearness and depth and to detect elements from the surface water of Hwajinpo Lake. Based on these results, water quality of the lake was analyzed, and the range of water quality was drawn graphically. According to comparison outcomes, the new technique of detecting water elements from DN of Landsat TM images and drawing the range of water quality produced a far more accurate pattern for a wide area than the direct measurement. To display the pattern more clearly, the stretching technique in particular was very effective in the pattern analysis.