• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2012.07a
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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.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.38A no.11
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• pp.919-927
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• 2013

In this paper, we present a perception-based tone mapping technique using histogram modification for displaying high dynamic range image. HDR (high dynamic range) tone mapping algorithms are used to display HDR image on LDR (low dynamic rnage) devices. Although perception-based tone mapping methods provides better performance, it dose not always produce good results for a wide variety of images. The proposed method reduces dynamic range by using the perception-based tone mapping function and histogram modification. A derivative of perception-based tone mapping function is used as constraint function of histogram and additional compensation process is performed. This method not only improves contrast by adopting different constraints on each pixel value, but also preserves more visual details. In order to prevent over enhancement, histogram modification technique is applied. Furthermore, it can control the rate of image contrast using control parameters. Subjective and objective evaluations show that proposed algorithm is better than existing algorithms.

• Korean Journal of Radiology
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• v.2 no.1
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• pp.28-36
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• 2001

Objective: To provide a systematic overview of the effects of various parameters on contrast enhancement within the same population, an animal experiment as well as a computer-aided simulation study was performed. Materials and Methods: In an animal experiment, single-level dynamic CT through the liver was performed at 5-second intervals just after the injection of contrast medium for 3 minutes. Combinations of three different amounts (1, 2, 3 mL/kg), concentrations (150, 200, 300 mgI/mL), and injection rates (0.5, 1, 2 mL/sec) were used. The CT number of the aorta (A), portal vein (P) and liver (L) was measured in each image, and time-attenuation curves for A, P and L were thus obtained. The degree of maximum enhancement (Imax) and time to reach peak enhancement (Tmax) of A, P and L were determined, and times to equilibrium (Teq) were analyzed. In the computed-aided simulation model, a program based on the amount, flow, and diffusion coefficient of body fluid in various compartments of the human body was designed. The input variables were the concentrations, volumes and injection rates of the contrast media used. The program generated the time-attenuation curves of A, P and L, as well as liver-to-hepatocellular carcinoma (HCC) contrast curves. On each curve, we calculated and plotted the optimal temporal window (time period above the lower threshold, which in this experiment was 10 Hounsfield units), the total area under the curve above the lower threshold, and the area within the optimal range. Results: A. Animal Experiment: At a given concentration and injection rate, an increased volume of contrast medium led to increases in Imax A, P and L. In addition, Tmax A, P, L and Teq were prolonged in parallel with increases in injection time The time-attenuation curve shifted upward and to the right. For a given volume and injection rate, an increased concentration of contrast medium increased the degree of aortic, portal and hepatic enhancement, though Tmax A, P and L remained the same. The time-attenuation curve shifted upward. For a given volume and concentration of contrast medium, changes in the injection rate had a prominent effect on aortic enhancement, and that of the portal vein and hepatic parenchyma also showed some increase, though the effect was less prominent. A increased in the rate of contrast injection led to shifting of the time enhancement curve to the left and upward. B. Computer Simulation: At a faster injection rate, there was minimal change in the degree of hepatic attenuation, though the duration of the optimal temporal window decreased. The area between 10 and 30 HU was greatest when contrast media was delivered at a rate of 2 3 mL/sec. Although the total area under the curve increased in proportion to the injection rate, most of this increase was above the upper threshould and thus the temporal window was narrow and the optimal area decreased. Conclusion: Increases in volume, concentration and injection rate all resulted in improved arterial enhancement. If cost was disregarded, increasing the injection volume was the most reliable way of obtaining good quality enhancement. The optimal way of delivering a given amount of contrast medium can be calculated using a computer-based mathematical model.

• KIPS Transactions on Software and Data Engineering
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• v.6 no.4
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• pp.211-216
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• 2017

This paper proposes image processing techniques that improve usability and performance in a diagnostic system of the contrast-enhanced ultrasonography. For a methodology for visualizing diagnostic parameter data in an ultrasonic medical image, an expression of transition time data with successive pixel values and a method of generating a lesion diagnostic parameter image with four categorized values are presented. We also introduce a MRF-based image enhancement technique to eliminate noises from generated parametric images. Such parametric image generation technique can overcome the difficulty of discriminating dynamic change in patterns in the ultrasonography. The technique clarifies the contour of the region in the original image and facilitates visual determination of the characteristics of the lesion through four colors. With regard to this MRF-based image enhancement, we define the energy function of consecutive pixel values and develop a technique to optimize it, and the usability of the proposed theory is examined through experiments with medical images.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2006.05a
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• pp.656-659
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• 2006

MD (DLP, LCoS) Projection TV is appropriate for large screen display with high definition at a relatively low price and thus, has been popular in the digital TV market. In order to realize high resolutions in the DLP projection TV, we successfully developed the Pixel Enhancement Actuator. Furthermore, it is also required that the contrast ratio of projected video signals onto a large screen should be improved. Therefore, we propose a contrast enhancer which adjusts the amount of projected lights by a dynamic aperture and a attached position sensor.

• Journal of the Korea Society of Computer and Information
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• v.24 no.6
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• pp.73-80
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• 2019

In this paper, we propose an effective dynamic range compression (DRC) method of infrared images. A histogram of infrared images has narrow dynamic range compared to visible images. Hence, it is important to apply the effective DRC algorithm for high performance of an infrared image analysis. The proposed algorithm for high dynamic range divides an infrared image into the overlapped blocks and calculates Shannon's entropy of overlapped blocks. After that, we classify each block according to the value of entropy and apply adaptive histogram modification method each overlapped block. We make an intensity mapping function through result of the adaptive histogram modification method which is using standard-deviation and maximum value of histogram of classified blocks. Lastly, in order to reduce block artifact, we apply hanning window to the overlapped blocks. In experimental result, the proposed method showed better performance of dynamic range compression compared to previous algorithms.

• Proceedings of the IEEK Conference
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• 2008.06a
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• pp.829-830
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• 2008

In modern days, many of the images are captured by using various devices, such as PDA, digital camera, or cell phone camera. Because all these devise have a limited dynamic range, images captured in real world scenes with high dynamic ranges usually exhibit poor visibility and low contrast, which may make important image features lost or hard to tell by human viewers. In this paper, the efficient color image enhancement method is presented. Experimental result show that the proposed method yields better performance of color enhancement over the previous work for test color images.

• Journal of radiological science and technology
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• v.20 no.2
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• pp.73-78
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• 1997

The goal of this paper is that we know the usefulness of echo-planar imaging(EPI) for discriminate between hepatocellular carcinoma(HCC) and hemangioma. We get a time signal intensity curve for liver diseases from the dynamic contrast enhancement images and compared and analyze both the contrast ratio(CR) and the contrast to noise ratio(CNR) using echo planar imaging. The obtained results are follows : 1. Hepatocellular carcinoma was shown the best contrast after about 20 seconds when Is the earlist time in the main artery, and then reduced. The center where is disease was shown the characteristic that the best contrast is appeared after about 35-45 seconds and then slowly reduced. Liver parenchyma was shown the best contrast and reduced after 60 seconds. 2. The peripheral nodular of hemangioma was shown the better contrast soon. On the other hend, the contrast of center where is disease started to increase after 60 seconds and was equal to that of liver parenchyma. Increasing of the contrast continued after. 3. Turbo SE technic was used, the average of CR for hepatocellular carcinoma was $36.7{\pm}1.2$ and the average of CNR was $2.4{\pm}3.2$, while the average of CNR for hemangioma was $54.9{\pm}1.0$ and the average of CNR was $9.7{\pm}1.3$. 4. EPI technic was used, the average of CR for hepatocellular carcinoma was $47.8{\pm}1.2$ and the average of CNR was $3.4{\pm}2.1$, while the average of CNR for hemangioma was $75.7{\pm}2.2$ and the average of CNR was $9.5{\pm}1.1$. According to above we can find that hemangioma is more bright than hepatocellular carcinoma and the difference of brightness between hepatocellular carcinoma and hemangioma is useful sequence.

• Current Optics and Photonics
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• v.5 no.4
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• pp.351-361
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• 2021

Speckle imaging is capable of dynamic data acquisition at high spatiotemporal resolution, and has played a vital role in the functional study of biological specimens. The presence of various optical scatterers within the tissue causes alteration of speckle contrast. Thus structures like blood vessels can be delineated and quantified. Although laser speckle imaging is frequently used, an optimization process to ensure the maximum speckle contrast has not been available. In this respect, we here report an experimental procedure to optimize speckle contrast via applying different combinations of varying polarization of the illuminating laser light and multiple analyzer angles. Specifically, samples were illuminated by the p-polarization, 45°-polarization, and s-polarization of the incident laser, and speckle images were recorded without and with the analyzer rotated from 0° to 180° (Δ = 30°). Following the baseline imaging of a solid diffuser and a fixed brain sample, laser speckle contrast imaging (LSCI) was successfully performed to visualize in vivo mouse-brain blood flow. For oblique laser illumination, the maximum contrast achieved with p-polarized and s-polarized light was perpendicular to the analyzer's axis. This study demonstrates the optimization process for maximizing the speckle contrast, which can improve blood-flow estimation in vivo.

• Journal of IKEEE
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• v.13 no.4
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• pp.116-124
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• 2009

Recently the CPU performance of modem chipsets or multimedia processors of mobile phone is as high as notebook PC. That is why mobile phone has been emerged as a leading ICON on the convergence of consumer electronics. The various applications of mobile phone such as DMB, digital camera, video telephony and internet full browsing are servicing to consumers. To meet all the demands the image quality has been increasingly important. Mobile phone is a portable device which is widely using in both the indoor and outside environments, so it is needed to be overcome to deteriorate image quality depending on environmental light source. Furthermore touch window is popular on the mobile display panel and it makes contrast loss because of low transmittance of ITO film. This paper presents the image enhancement algorithm to be embedded on image enhancement SoC. In contrast enhancement, we propose Clipped histogram stretching method to make it adaptive with the input images, while S-shape curve and gain/offset method for the static application And CIELCh color space is used to sunlight readability enhancement by controlling the lightness and chroma components which is depended on the sensing value of light sensor. Finally the performance of proposed algorithm is evaluated by using histogram, RGB pixel distribution, entropy and dynamic range of resultant images. We expect that the proposed algorithm is suitable for image enhancement of embedded SoC system which is applicable for the small-sized mobile display.