• 제목/요약/키워드: contrast analysis

검색결과 3,295건 처리시간 0.028초

Retinex 처리에 기반한 적외선 열상 이미지의 화질 개선 (Thermal Infrared Image Enhancement Method Based on Retinex)

  • 이원석;김경희;이상원
    • 전자공학회논문지 IE
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    • 제48권2호
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    • pp.32-39
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    • 2011
  • 비냉각형 적외선 검출기를 사용한 적외선 열상 카메라의 영상은 다이나믹 레인지가 좁고 신호 증폭에 의한 노이즈로 인하여 피사체를 식별하기 어려운 단점이 있다. 인간의 시각모델을 기반으로 한 레티넥스 알고리즘은 콘트라스트 향상 및 컬러 재현성에 있어서 매우 효과적인 방법으로 알려져 있다. 하지만, 적외선 열상 이미지와 같이 다이나믹 레인지가 좁은 영상에 레티넥스 알고리즘을 적용할 경우 오히려 콘트라스트가 감소하고 이미지 품질이 저하된다. 본 논문에서는 적외선 열상 이미지의 특성에 적합한 레티넥스 알고리즘 기반의 화질 개선 방법을 제안한다. 콘트라스트 개선 성능을 향상시키기 위해 새로운 다이나믹 레인지 압축 함수를 사용하였고, 국부적인 윤곽과 노이즈를 개선하기 위해 콘트라스트 보상 처리를 영상의 합성 과정에 적용하였다. 실험 결과 영상의 비교와 분석을 통해 제안한 알고리즘이 기존의 알고리즘보다 적외선 열상 이미지의 화질 개선에 더 효과적인 방법임을 확인하였다.

Quantitative Analysis of Microperfusion in Contrast-Induced Nephropathy Using Contrast-Enhanced Ultrasound: An Animal Study

  • Nieun Seo;Hyewon Oh;Hyung Jung Oh;Yong Eun Chung
    • Korean Journal of Radiology
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    • 제22권5호
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    • pp.801-810
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    • 2021
  • Objective: To investigate imaging biomarkers of microperfusion in contrast-induced nephropathy (CIN) using contrast-enhanced ultrasound (CEUS). Materials and Methods: The CIN model was fabricated by administering indomethacin (10 mg/kg), L-NAME (15 mg/kg), and iopamidol (10 mL/kg) to Sprague-Dawley rats. After 24 hours, CEUS was performed on CIN (n = 6) and control (n = 6) rats with sulphur hexafluoride microbubbles (SonoVue). From time-intensity curves obtained from the kidney arriving time (AT), acceleration time (AC), time to peak (TTP), and peak enhancement (PE) were measured and compared between the groups. After CEUS, the rats were sacrificed, and cell apoptosis markers were evaluated to confirm the development of CIN. Results: Among CEUS parameters, AT (7.8 ± 1.6 vs. 4.2 ± 0.5 s, p = 0.002), AC (4.7 ± 1.4 vs. 2.0 ± 0.4 s, p = 0.002), and TTP (12.5 ± 2.9 vs. 6.2 ± 0.6 s, p = 0.002) were significantly prolonged in the CIN group compared to controls. PE was significantly higher in the control group than in the CIN group (17.1 ± 1.9 vs. 12.2 ± 2.0 dB, p = 0.004). In kidney tissue, mRNA and protein levels of the apoptotic makers were significantly higher in the CIN group than in the control group (p = 0.003 and p = 0.002). Conclusion: CEUS parameters can be used as imaging biomarkers for microperfusion in CIN. In rats with CIN, AT, AC, and TTP were significantly prolonged, while PE was significantly lower compared to controls.

Luminance enhancement in single image dehazing

  • ;김원하
    • 한국방송∙미디어공학회:학술대회논문집
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    • 한국방송공학회 2013년도 하계학술대회
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    • pp.322-324
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    • 2013
  • Haze is an extreme reason of the reduction of contrast when capturing image in the outdoor. Recently, there are several single image dehazing techniques, but they are not robust in dynamic variations of natural environment caused by the thickness, coverage of haze and appearance of sunlight. In this paper, we propose an effective and robust method to enhance luminance for image dehazing depending on histogram analysis. Compare with conventional methods, our proposal have better performance in term of contrast, and computation time.

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Histogram-based luminance enhancement for image dehazing

  • Bui, Minh-Trung;Kim, Won-Ha
    • 한국방송∙미디어공학회:학술대회논문집
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    • 한국방송공학회 2012년도 하계학술대회
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    • pp.16-18
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    • 2012
  • Haze is an extreme reason of the reduction of contrast when capturing image in the outdoor. Recently, there are several single image dehazing techniques, but they are not robust in dynamic variations of natural environment caused by the thickness, coverage of haze and appearance of sunlight. In this paper, we propose an effective and robust method to enhance luminance for image dehazing depending on histogram analysis. Compare with conventional methods, our proposal have better performance in term of contrast, and computation time.

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연안수리현상 파악을 위한 LANDSAT MSS Data의 처리와 해석 -인천해역을 중심으로- (Processing and Analysis of LANDSAT MSS Data for Extraction of Coastal Flow Patterns - around Incheon Bay -)

  • 안철호;안기원;안호준
    • 한국측량학회지
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    • 제4권2호
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    • pp.59-75
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    • 1986
  • 본 연구는 LANDSAT MSS Data를 연안해역의 수리현상파악을 목적으로 이용하는 경우의 가장 효과적인 화상해석방법을 모색한 것이다. 우리나라 인천지역을 대상으로, 육역에 비하여 CCT Data값이 낮은 해역의 LANDSAT MSS Data를 사용하여 화상강조의 기법인 Contrast 강조처리, Color 합성처리 및 비연산처리 등 화상처리를 실행함으로써, 연안해수역의 유동특성을 파악하기 위한 가장 효과적인 LANDSAT MSS Data의 화상해석순서를 제안하였다.

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Aortic arch를 포함한 Carotid angio 검사 시 Time of flight(TOF)의 유용성 평가 (Usefulness estimating of Time of flight(TOF) during Carotid angio inspection including Aortic arch)

  • 유영준
    • 대한디지털의료영상학회논문지
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    • 제15권1호
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    • pp.1-7
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    • 2013
  • Purpose : The Carotid Angio inspection including Aortic arch applied to wide area is conducted as the Contrast Enhance MR Angiography(CEA) which is using a contrast medium. However it is a burden not only for someone such as infants, pregnant women and patients suffering from kidney failure but continuous use of contrast medium also can be a burden for patients who has been taken follow up inspection since diagnose lesion already. The purpose of this study is to estimate a usefulness of the Time of Flight (TOF) by comparing with CEA. Materials and methods : 10 patients with an average age of 58 (from 45 to 75) who had MRA inspection in our hospital were studied using 3.0 Tesla Aachieva (Philips, Netherland) MRI system and Sense Neuro-Vascular 16 Channels Coil. The same patient was inspected both TOF and CEA simultaneously. The TOF inspection included from Aortic arch to Willis Circle by connecting 3 TOF stacks and so did CEA inspection. The quantitative analysis was conducted through signal to noise ratio(SNR) and contrast to noise ratio(CNR) with soft tissue by setting up an area of interest on CCA bifurcatoin, ICA, ECA, MCA and VA concerning obtained image. In case of qualitative analysis, 3 radiological technologists and 1 radiologist evaluated 4 items (1: Visibility of the blood vessel, 2: Image distortion measure, 3: Overlapping measure with vein, 4: Peripheral blood vessel description measure) into five points scale (1: Very bad, 2: Bad, 3: Normal 4: Good, 5: Very good). Results : Results for the quantitative analysis was obtained by calculating the average of 5 ROIs in case of SNR and CNR separately. Results of SNR, TOF were generally measured higher than CEA (In case of TOF were 166.1, 205.2, 154.39, 172.23, 161.95, and CEA were 92.05, 95.43, 84.76, 73.69, 88.3). But according to the result of CNR, both TOF and CEA were measured similarly as 67.62, 106.71, 55.9, 73.74, 63.46 for TOF and 67.82, 71.19, 60.52, 49.45, 64.07 for CEA. Throughout every results of each ROI, SNR showed statistically meaningful consequence (0.050.05). In case of qualitative analysis the average of each evaluated item was 4.2points and 4.28points in the item1, 2.93points and 4.55points in the item2, 4.6points and 3.13points in the item3, 2.88points and 4.6points in the item4. According to the results TOF was measured higher in the item3 while in the item2 and item4 CEA was higher and in case of the item1, both CEA and TOF were similar. To sum up statistically meaningful results (p<0.05) were shown in the item2, item3 and item4 but not in the item1 (p>0.05). Conclusions : Both TOF and CEA are complementary because each inspection has pros and cons, but when inspect wide area including Aortic arch normally CEA is conducted. But TOF inspection also can be considered as alternative in terms of patients who has difficulty in the contrast medium such as infants, pregnant women and patients suffering from kidney failure and patients during follow up.

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Prognostic Value of Dynamic Contrast-Enhanced MRI-Derived Pharmacokinetic Variables in Glioblastoma Patients: Analysis of Contrast-Enhancing Lesions and Non-Enhancing T2 High-Signal Intensity Lesions

  • Yeonah Kang;Eun Kyoung Hong;Jung Hyo Rhim;Roh-Eul Yoo;Koung Mi Kang;Tae Jin Yun;Ji-Hoon Kim;Chul-Ho Sohn;Sun-Won Park;Seung Hong Choi
    • Korean Journal of Radiology
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    • 제21권6호
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    • pp.707-716
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    • 2020
  • Objective: To evaluate pharmacokinetic variables from contrast-enhancing lesions (CELs) and non-enhancing T2 high signal intensity lesions (NE-T2HSILs) on dynamic contrast-enhanced (DCE) magnetic resonance (MR) imaging for predicting progression-free survival (PFS) in glioblastoma (GBM) patients. Materials and Methods: Sixty-four GBM patients who had undergone preoperative DCE MR imaging and received standard treatment were retrospectively included. We analyzed the pharmacokinetic variables of the volume transfer constant (Ktrans) and volume fraction of extravascular extracellular space within the CEL and NE-T2HSIL of the entire tumor. Univariate and multivariate Cox regression analyses were performed using preoperative clinical characteristics, pharmacokinetic variables of DCE MR imaging, and postoperative molecular biomarkers to predict PFS. Results: The increased mean Ktrans of the CEL, increased 95th percentile Ktrans of the CELs, and absence of methylated O6-methylguanine-DNA methyltransferase promoter were relevant adverse variables for PFS in the univariate analysis (p = 0.041, p = 0.032, and p = 0.083, respectively). The Kaplan-Meier survival curves demonstrated that PFS was significantly shorter in patients with a mean Ktrans of the CEL > 0.068 and 95th percentile Ktrans of the CEL > 0.223 (log-rank p = 0.038 and p = 0.041, respectively). However, only mean Ktrans of the CEL was significantly associated with PFS (p = 0.024; hazard ratio, 553.08; 95% confidence interval, 2.27-134756.74) in the multivariate Cox proportional hazard analysis. None of the pharmacokinetic variables from NE-T2HSILs were significantly related to PFS. Conclusion: Among the pharmacokinetic variables extracted from CELs and NE-T2HSILs on preoperative DCE MR imaging, the mean Ktrans of CELs exhibits potential as a useful imaging predictor of PFS in GBM patients.

An Optimized Multiple Fuzzy Membership Functions based Image Contrast Enhancement Technique

  • Mamoria, Pushpa;Raj, Deepa
    • KSII Transactions on Internet and Information Systems (TIIS)
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    • 제12권3호
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    • pp.1205-1223
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    • 2018
  • Image enhancement is an emerging method for analyzing the images clearer for interpretation and analysis in the spatial domain. The goal of image enhancement is to serve an input image so that the resultant image is more suited to the particular application. In this paper, a novel method is proposed based on Mamdani fuzzy inference system (FIS) using multiple fuzzy membership functions. It is observed that the shape of membership function while converting the input image into the fuzzy domain is the essential important selection. Then, a set of fuzzy If-Then rule base in fuzzy domain gives the best result in image contrast enhancement. Based on a different combination of membership function shapes, a best predictive solution can be determined which can be suitable for different types of the input image as per application requirements. Our result analysis shows that the quality attributes such as PSNR, Index of Fuzziness (IOF) parameters give different performances with a selection of numbers and different sized membership function in the fuzzy domain. To get more insight, an optimization algorithm is proposed to identify the best combination of the fuzzy membership function for best image contrast enhancement.

스캔 인자에 따른 4D 위상 대조 자기공명영상을 이용한 스캔 시간 분석: 팬텀 연구 (Scan Time Analysis Using 4D Phase-Contrast MRI According to Scan Parameter: A Phantom Study)

  • 박지은;김정훈;황문정;이종민
    • 대한의용생체공학회:의공학회지
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    • 제41권5호
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    • pp.179-184
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    • 2020
  • Purpose: The purpose of this study was to evaluate the effect according to the NEX, VENC, targeted cardiac phases on the velocity measurement of 4D phase-contrast MRI. Materials and Methods: The abdominal aortic phantom was made to experiment. The working fluid was mixed with water and glycerin to mimic the density and viscosity of human blood. The inlet velocity was Reynolds number 2000. The experimental conditions were NEX 1 and 4, VENC 102 cm/s and 200 cm/s, and 10 and 15 targeted cardiac phases, respectively. The average flow rate, average velocity, maximum velocity, and cross-section area were measured. Results: As a result of the case-by-case comparison, the error rate was less than 5%. There was no significant difference (p > 0.05). Conclusion: It is expected that this result will be useful for acquiring blood flow information in clinical practice.