• Journal of Information Technology Applications and Management
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• 제25권2호
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• pp.41-52
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• 2018

This paper presents a method for accurate camera self-calibration based on SIFT Feature Detection and image quality assessment. We performed image quality assessment to select high quality images for the camera self-calibration process. We defined high quality images as those that contain little or no blur, and have maximum contrast among images captured within a short period. The image quality assessment includes blur detection and contrast assessment. Blur detection is based on the statistical analysis of energy and standard deviation of high frequency components of the images using Discrete Cosine Transform. Contrast assessment is based on contrast measurement and selection of the high contrast images among some images captured in a short period. Experimental results show little or no distortion in the perspective view of the images. Thus, the suggested method achieves camera self-calibration accuracy of approximately 93%.

• 한국멀티미디어학회논문지
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• 제14권11호
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• pp.1365-1372
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• 2011

본 논문은 어두운 영상의 낮은 인지적인 대비를 향상하기 위해 비선형 마스킹 기법을 이용한 영상의 인지적 대비 향상 방법을 제안한다. 영상의 주요 속성인 색도의 변화를 최소화 하면서 어두운 영역의 밝기를 향상시키기 위해, 비선형 마스킹 기법 기반으로 영상에 적응적인 파라미터를 이용한 대비 향상방법을 제안하 였다. 제안하는 방법의 성능을 평가하기 위해 테스트 영상에 대해 SSR(Single-Scale Retinex), MSR(Multi-Scale Retinex), 기존의 비선형 마스킹 기법의 결과와 색도 및 채도에 대한 정량적인 평가와, z-score를 이용한 정성적 평가를 수행하였다. 결과 제안한 방법이 낮은 색도 변화와 향상된 인지적 대비를 보임을 확인하였다.

• 대한자기공명의과학회:학술대회논문집
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• 대한자기공명의과학회 2003년도 제8차 학술대회 초록집
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• pp.93-93
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• 2003

To test the feasibility of rBF and rBVin the assessment of R004 sarcomas of the rat and to compare the results obtained by using Gd-DTPA and Gadomer-17 as a MR contrast agent, on the basis of the histological findings of tumor necrosis.

• 한국조경학회지
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• 제32권4호
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• pp.94-104
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• 2004

This study creates the LCP (Landscape Control Point) through the survey of spot sites for the quality of landscape assessment, which is based on an objective and departmentalized data base; the landscape assessment was achieved by production of weight value with the AHP (Analytic Hierarchy Process) technique, selection of requisites for the landscape assessment with the IVERSON method and visual area analysis with GIS (Geographic Information System). Futhermore, validity of the landscape assessment was verified by analysis of the correlation between physical amount and aesthetic amount. The purpose of this study is to suggest the basic essential data for landscape assessment and landscape planning by the characteristics of landscape based on verification of the suggested landscape assessment methods. The results of this study are summarized below. 1. In the adaptation of landscape assessment using GIS, the landscape assessment points of LCP 18, 17 and 16, which have more visible elements such as hill area, mountain area, and forest and farm land, were indicated to be higher than the others. In contrast, the landscape assessment points of LCP 13, 6 and 10, which have less visible elements, were relatively lower than the others. 2. In the visible preference measuring method, LCP 4, 14, and 16 showed high points of landscape assessment with 3.46, 3.4, and 3.18 each. With the more natural environments such as hill area, mountain area, and forest and farm land, higher results were shown. In contrast, LCP 7, 1, and 9 showed low points of landscape assessment with 2.24, 2.36, and 2.53 each. 3. In this study, a coefficient of 0.746 was gained by the analysis of correlation between the points of landscape assessment method and the points of visual preference from a slide show. This has 99 percent of probability in statistical data. 4. In conclusion, with the demonstration of the correlation between the landscape assessment method based on the AHP technique and the aesthetic amount (preference proportion), the practical use of landscape assessment can be demonstrated by the suggested landscape assessment method.

• The Journal of the Acoustical Society of Korea
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• 제24권1E호
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• pp.28-33
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• 2005

This study was designed to suggest an assessment tool for analyzing the characteristics of Korean phonetic contrast intelligibility among dysarthric individuals. The intelligibility deficit factors of phonetic contrast in Korean dysarthric patients were analyzed through stepwise regression analysis. The 19 acoustic-phonetic contrasts proposed by Kent et al. (1999) have been claimed to be useful for clinical assessment and research on dysarthria. However, the test cannot be directly applied to Korean patients due to linguistic differences between English and Korean. Thus, it is necessary to devise a Korean word intelligibility test that reflects the distinct characteristics of the Korean language. To identify the speech error characteristics of a Korean dysarthric group, a Korean word list was audio-recorded by 3 spastic, 4 flaccid, and 5 mixed type of dysarthric patients. The word list consisted of monosyllabic consonant-vowel-consonant (CVC) real word pairs. Stimulus words included 41 phonemic contrast pairs and six triplets. The results showed that the percentage of errors in final position contrast was higher than in any other position. Unlike the results of previous studies, the initial-position contrasts were crucial in predicting the overall intelligibility among Korean patients.

• 방사선산업학회지
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• 제12권4호
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• pp.325-332
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• 2018

Carotid angiography covering the aortic arch includes contrast-enhanced magnetic resonance angiography (CEA), which is applied to a large region and usually employs contrast media. However, the use of contrast media can be dangerous in infants, pregnant women, and patients with chronic renal failure (CRF). Follow-up patients informed of a lesion may also want to avoid constant exposure to contrast media. We aimed to apply time-of-flight (TOF) angiography to a large region and compare its usefulness with that of CEA. Ten patients (mean age, 58 years; range, 45~75 years) who visited our hospital for magnetic resonance angiography (MRA) participated in this study. A 3.0 Tesla Achieva magnetic resonance imaging (MRI) system (Philips, Netherland) and the SENSE NeuroVascular 16-channel coil were employed for both methods. Both methods were applied simultaneously to the same patient. Three TOF stacks were connected to cover the aortic arch through the circle of Willis, and CEA was applied in the same manner. For the quantitative assessment, the acquired images were used to set the regions of interest (ROIs) in the common carotid artery (CCA) bifurcation, internal carotid artery, external carotid artery, middle cerebral artery, and vertebral artery, and to obtain the signal-to-noise ratio (SNR) and the contrast-to-noise ratio (CNR) for the soft tissues. Three radiologists and one radiological resident performed the qualitative assessment on a 5-point scale - 1 point, "very bad"; 2 points, "bad"; 3 points, "average"; 4 points, "good"; and 5 points, "very good" - with regard to 4 items: (1) sharpness, (2) distortion, (3) vein contamination, and (4) expression of peripheral vessels. For the quantitative assessment, we estimated the mean SNR and CNR in each of the 5 ROIs. In general, the mean SNR was higher in TOF angiography (166.1, 205.2, 154.39, 172.23, and 161.95) than in CEA(92.05, 95.43, 84.76, 73.69, and 88.3). Both methods had a similar mean CNR: 67.62, 106.71, 55.9, 73.74, and 63.46 for TOF angiography, and 67.82, 71.19, 60.52, 49.45, and 64.07 for CEA. In all ROIs, the mean SNR was statistically significant (p<0.05), whereas the mean CNR was insignificant (p>0.05). The mean values of TOF angiography and CEA for each item in the qualitative assessment were 4.2 and 4.28, respectively for item 1; 2.93 and 4.55, respectively, for item 2; 4.6 and 3.13, respectively, for item 3; and 2.88 and 4.65, respectively, for item 4. Therefore, TOF angiography had a higher mean for item 3, and CEA had a higher mean for items 2 and 4; there was no significant difference between the two methods for item 1. The results for item 1 were statistically insignificant (p>0.05), whereas the results for items 2~4 were statistically significant (p<0.05). Both methods have advantages and disadvantages and they complement each other. However, CEA is usually applied to a large region covering the aortic arch. Time-of-flight angiography may be useful for people such as infants, pregnant women, CRF patients, and followup patients for whom the use of contrast media can be dangerous or unnecessary, depending on the circumstance.

• 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.

• 전기학회논문지P
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• 제62권2호
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• pp.90-94
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• 2013

In this paper, we propose a new algorithm to improve the contrast ratio, to preserve information of bright regions and to maintain the color of backlight image that appears with a great relative contrast. Backlight images of the natural environment have characteristics for difference of local brightness; the overall image contrast improvement is not easy. To improve the contrast of the backlight images, MSR (Multi-Scale Retinex) algorithm using the existing multi-scale Gaussian filter is applied. However, existing multi-scale Gaussian filter involves color distortion and information loss of bright regions due to excessive contrast enhancement and noise because of the brightness improvement of dark regions. Moreover, it also increases computational complexity due to the use of multi-scale Gaussian filter. In order to solve these problems, a linear MSR is performed that reduces the amount of computation from the HSV color space preventing the color distortion and information loss due to excessive contrast enhancement. It can also remove the noise of the dark regions which is occurred due to the improved contrast through edge preserving filter. Through experimental evaluation of the average color difference comparison of CIELAB color space and the visual assessment, we have confirmed excellent performance of the proposed algorithm compared to conventional MSR algorithm.

• 대한수의학회지
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• 제55권1호
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• pp.47-52
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• 2015

The purpose of this study was to determine if contrast media would enhance visualization of the endocardium for assessment of left ventricle (LV) function. In addition, differences between pre- and post-contrast evaluation for the cardiac output measurements including the modified Simpson's method and automated contour tracking (ACT) method were examined. Ten clinically healthy adult beagle dogs (three males and seven females) between 2~3 years old and weighing 6.6~10.8 kg were used. Echocardiographic examinations were performed to compare pre- and post-contrast LV endocardium visualization using a segmental scoring method. Two different methods for measuring cardiac output were also compared. LV visualization was significantly enhanced in post-contrast echocardiography (p < 0.01). Significant differences between pre- and post-contrast measurements for the modified Simpson's method (p < 0.05) were also observed. No significant difference was found for the ACT method. Contrast echocardiography provides better LV chamber opacification and significantly improves wall segment visualization. Furthermore, contrast echocardiography for measuring cardiac output is helpful for the modified Simpson's method.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제15권11호
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• pp.4043-4064
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• 2021

Night-time image quality evaluation is an urgent requirement in visual inspection. The lighting environment of night-time results in low brightness, low contrast, loss of detailed information, and colour dissonance of image, which remains a daunting task of delicately evaluating the image quality at night. A new blind quality assessment metric is presented for realistic night-time scenario through a comprehensive consideration of contrast, texture, and colour in this article. To be specific, image blocks' color-gray-difference (CGD) histogram that represents contrast features is computed at first. Next, texture features that are measured by the mean subtracted contrast normalized (MSCN)-weighted local binary pattern (LBP) histogram are calculated. Then statistical features in Lαβ colour space are detected. Finally, the quality prediction model is conducted by the support vector regression (SVR) based on extracted contrast, texture, and colour features. Experiments conducted on NNID, CCRIQ, LIVE-CH, and CID2013 databases indicate that the proposed metric is superior to the compared BIQA metrics.