• Title/Summary/Keyword: Low Contrast

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An Image Contrast Enhancement Technique Using Integrated Adaptive Fuzzy Clustering Model (IAFC 모델을 이용한 영상 대비 향상 기법)

  • 이금분;김용수
    • Proceedings of the Korean Institute of Intelligent Systems Conference
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    • 2001.12a
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    • pp.279-282
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    • 2001
  • This paper presents an image contrast enhancement technique for improving the low contrast images using the improved IAFC(Integrated Adaptive Fuzzy Clustering) Model. The low pictorial information of a low contrast image is due to the vagueness or fuzziness of the multivalued levels of brightness rather than randomness. Fuzzy image processing has three main stages, namely, image fuzzification, modification of membership values, and image defuzzification. Using a new model of automatic crossover point selection, optimal crossover point is selected automatically. The problem of crossover point selection can be considered as the two-category classification problem. The improved MEC can classify the image into two classes with unsupervised teaming rule. The proposed method is applied to some experimental images with 256 gray levels and the results are compared with those of the histogram equalization technique. We utilized the index of fuzziness as a measure of image quality. The results show that the proposed method is better than the histogram equalization technique.

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Image saliency detection based on geodesic-like and boundary contrast maps

  • Guo, Yingchun;Liu, Yi;Ma, Runxin
    • ETRI Journal
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    • v.41 no.6
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    • pp.797-810
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    • 2019
  • Image saliency detection is the basis of perceptual image processing, which is significant to subsequent image processing methods. Most saliency detection methods can detect only a single object with a high-contrast background, but they have no effect on the extraction of a salient object from images with complex low-contrast backgrounds. With the prior knowledge, this paper proposes a method for detecting salient objects by combining the boundary contrast map and the geodesics-like maps. This method can highlight the foreground uniformly and extract the salient objects efficiently in images with low-contrast backgrounds. The classical receiver operating characteristics (ROC) curve, which compares the salient map with the ground truth map, does not reflect the human perception. An ROC curve with distance (distance receiver operating characteristic, DROC) is proposed in this paper, which takes the ROC curve closer to the human subjective perception. Experiments on three benchmark datasets and three low-contrast image datasets, with four evaluation methods including DROC, show that on comparing the eight state-of-the-art approaches, the proposed approach performs well.

A Study on Comparative Analysis of Diffusion Weighted Image Examination before and after Contrast Injection (조영제 사용 전 후 확산강조영상 검사의 비교 분석에 대한 연구)

  • Goo, Eun-Hoe
    • Korean Journal of Digital Imaging in Medicine
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    • v.11 no.2
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    • pp.51-57
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    • 2009
  • The purpose of this study would evaluate if having clinical effects on diffusion image with quantitative analysis through ADC values of brain's normal tissue and lesions before and after contrast injections using a 3.0T. From November in 2007 until December in 2008, a total of 32 patient was performed on 3.0T(Signa Excite, GE Medical System, USA) with the normal or lesions in the patient who requests diffusion weighted image with 8channel head coil. The pulse sequence was used with spin echo EPI(TR: 10000msec, TE: 72.2 msec, Matrix: 128*128, FOV: 240 mm, NEX: 1, diffusion direction: 3, b-value: 1000). Measurement results of ADC values on lesions, CSF, white matter, gray matter, lesions after contrast injection were measured less 75% than before contrast injection, infarction: 100%, CSF: 78%(high), white matter: 71.4%(low), gray matter: 50%(high, low). The results of paired t-test on the deference of ADC values which statically is significant in three(lesions, CSF, white matter)regions except for white matter(p<0.05). Quantitative analysis of lesions, CSF, white matter, gray matter have difference on all regions. ADC values were low in lesions and white matter, normal CSF after contrast injection commonly is high than before contrast injection, ADC values which white matter were high and low (50:50) after contrast injection. 3.0T diffusion weighted image clinically supposed that performing DWI examination after contrast injection was not desirable because of having effects on brain tissue.

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How Computed Tomography Contrast Media and Magnetic Resonance Imaging Contrast Media Affect the Changes of Uptake Counts of 201Tl

  • Lee, Jin-Hyeok;Lee, Hae-Kag;Cho, Jae-Hwan;Cheon, Miju
    • Journal of Magnetics
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    • v.19 no.4
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    • pp.372-377
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    • 2014
  • The purpose of the study is to investigate how uptake counts of $^{201}Tl$ of radioisotopes in the human body could change, when taking computed tomography and magnetic resonance imaging right after injecting contrast media. $^{201}Tl$ radioisotope substances of iodine contrast medium, which is a computed tomography contrast medium, and paramagnetic contrast medium, which is an magnetic resonance imaging contrast medium, were used as study materials. First, $^{201}Tl$ was put into 4 cc of normal saline in test tube, and then a computed tomography contrast medium of Iopamidol$^{(R)}$ or Dotarem$^{(R)}$, was put into 2 cc of normal saline in test tube. An magnetic resonance imaging contrast medium of Primovist$^{(R)}$ or Gadovist$^{(R)}$ was also put into 2 cc of normal saline in test tube. Each contrast medium was distributed to make $^{201}Tl$ as 3 mCi, with a total of 4 cc. Gamma camera, low energy high resolution collimator, and pinhole collimator were used to obtain images. The uptake count of $^{201}Tl$ was measured with 1000 frames of images, and obtained after 10 times of repetition. This study revealed that the use of Gadovist$^{(R)}$, which is an magnetic resonance imaging contrast medium, showed the smallest number of uptake count, after measuring $^{201}Tl$ uptake count by low energy high resolution collimator. On the other hand, the use of Iopamidol$^{(R)}$, which is a computed tomography contrast medium, showed the biggest difference in uptake count, when measuring $^{99m}Tc$ uptake count by Pinhole collimator. When examining with gamma camera, using contrast medium and $^{201}Tl$, identifying the changes of uptake count is very important for improving the value of diagnosis.

A Comparative Study on Image Enhancement Methods for Low Contrast Images (저대비 영상을 위한 영상향상 기법들의 비교연구)

  • Kim Yong-Soo;Kim Nam-Jin;Lee Se-Yul
    • Proceedings of the Korean Institute of Intelligent Systems Conference
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    • 2005.04a
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    • pp.269-272
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    • 2005
  • The principal objective of enhancement methods is to process an image so that the result is more suitable than the original image for a specific application. Images taken in the night can be low-contrast images because of poor environments. In this paper, we compare the structure of ICECA(Image Contrast Enhancement technique using Clustering Algorithm) with the structures of HE(Histogram Equalization), BBHE(Brightness preserving Bi-Histogram Equalization), and Multi -Scale Retinex(MSR). We compared performances of image enhancement methods by applying these methods to a set of diverse images.

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A Study on the Classification of Surface Defect Based on Deep Convolution Network and Transfer-learning (신경망과 전이학습 기반 표면 결함 분류에 관한 연구)

  • Kim, Sung Joo;Kim, Gyung Bum
    • Journal of the Semiconductor & Display Technology
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    • v.20 no.1
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    • pp.64-69
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    • 2021
  • In this paper, a method for improving the defect classification performance in low contrast, ununiformity and featureless steel plate surfaces has been studied based on deep convolution neural network and transfer-learning neural network. The steel plate surface images have low contrast, ununiformity, and featureless, so that the contrast between defect and defect-free regions are not discriminated. These characteristics make it difficult to extract the feature of the surface defect image. A classifier based on a deep convolution neural network is constructed to extract features automatically for effective classification of images with these characteristics. As results of the experiment, AlexNet-based transfer-learning classifier showed excellent classification performance of 99.43% with less than 160 seconds of training time. The proposed classification system showed excellent classification performance for low contrast, ununiformity, and featureless surface images.

New Address Waveform for Improvement of the Priming Effect and the Contrast Ratio (AC-PDP에서 프라이밍 효과를 이용한 대조비 향상에 관한 연구)

  • Kwon, Shi-Ok;Kim, Ji-Sun;Joung, Bong-Kyu;Hwang, Ho-Jung
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.17 no.10
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    • pp.1120-1124
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    • 2004
  • Recently, Plasma Display Panel(PDP) has been in the spotlight as one of the next generation flat-panel-display device. However, it has several drawbacks like the low contrast ratio and the low luminance. In this study, a new address waveform is suggested to improve the priming effect and contrast ratio at the address period in the Address Display period Separated(ADS) method. We modified waveform, instead of a conventional waveform, to an address period, for operating on the Plasma Display Panels, which used the conventional gas [He-Ne-Xe〕. When the ramp pulse is added to the address period at the sustain electrode, it is improved on the priming effect and contrast ratio.

Effects on the Escapement of Juvenile Bastard Halibut Paralichthys olivaceus of Actively Stimulating Devices Inside a Model Cod End

  • Kim, Yong-Hae
    • Fisheries and Aquatic Sciences
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    • v.14 no.1
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    • pp.62-69
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    • 2011
  • The effects of actively stimulating devices (ASD) on juvenile flatfish escape were studied to increase escape rates from the cod end by encouraging fish to approach the net wall. Two kinds of ASD were designed: a fluttering net panel, i.e., a free-end flag-like net panel, and a double conical rope array. Escape responses of juvenile bastard halibut were observed in a circulating water channel using two model cod ends, one made with diamond-shaped 43-mm-mesh-size polyethylene (PE) as a high-contrast cod end and the other with polyamid (PA) mono-ply as a low-contrast cod end. Retention rate was significantly lower with the double conical rope-array ASD in the PE cod end than with conventional PE cod ends only or the fluttering net-panel ASD inside the PE cod end. Mean retention rate with the low-contrast PA cod end was also significantly lower than that with the high-contrast PE conventional cod end. Therefore, active fluttering devices using a double conical rope array together with less visible low-contrast netting in the cod end could help to reduce the bycatch of juvenile flatfish by weakening their optomotor response and actively driving fish to the side net panel.

Blind Quality Metric via Measurement of Contrast, Texture, and Colour in Night-Time Scenario

  • Xiao, Shuyan;Tao, Weige;Wang, Yu;Jiang, Ye;Qian, Minqian.
    • KSII Transactions on Internet and Information Systems (TIIS)
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    • v.15 no.11
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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.

Spontaneous Echo Contrast Observed on Carotid Duplex Ultrasonography (경동맥이중초음파검사에서 관찰된 자발에코대조)

  • Minho HAN
    • Korean Journal of Clinical Laboratory Science
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    • v.56 no.3
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    • pp.273-276
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    • 2024
  • Spontaneous echo contrast is a swirling, smoke-like echographic pattern observed in B-mode ultrasound imaging, typically arising in areas of blood stasis or low-flow states. This hemodynamic disturbance generates low shear stress due to sluggish flow, leading to endothelial dysfunction and facilitating the activation of fibrinogen, a coagulation factor. Consequently, blood cells, including erythrocytes, readily aggregate, forming a spontaneous echo contrast, a precursor to thrombus formation. Spontaneous echo contrast is primarily found in the left atrium of patients with left atrial enlargement or the left atrial appendage of patients with atrial fibrillation. While less common, it can also be observed in the carotid arteries. This case report presents the imaging findings of spontaneous echo contrast detected during carotid duplex ultrasonography in a patient with metastatic cancer and discusses its clinical implications.