• 한국정보디스플레이학회:학술대회논문집
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• 2008.10a
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• pp.870-872
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• 2008

It is known that AC electric field to drive IPS mode of liquid crystal display (LCD) causes reduction of the contrast after long period of display operation. Our results are presented in this paper on a base of a model of interaction between surface of PI alignment film and LC molecules. We conclude that the surface viscosity of PI alignment film is one of the most important factors for the contrast reduction phenomenon.

• IEIE Transactions on Smart Processing and Computing
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• v.3 no.6
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• pp.358-365
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• 2014

This paper proposes a method that reduces the flickering effect caused by A-GLG (Adaptive Gray-Level Grouping) during video contrast enhancement. Of the GLG series, A-GLG shows the best contrast enhancement performance. The GLG series is based on histogram grouping. Histogram grouping is calculated differently between the continuous frames with a similar histogram and causes a subtle change in the transformation function. This is the reason for flickering effect when the video contrast is enhanced by A-GLG. To reduce the flickering effect caused by A-GLG, the proposed method calculates a modified transformation function. The modified transformation function is calculated using a previous and current transformation function applied with a weight separately. The proposed method was compared with A-GLG for flickering effect reduction and video contrast enhancement. Through the experimental results, the proposed method showed not only a reduced flickering effect, but also video contrast enhancement.

• Journal of the Optical Society of Korea
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• v.14 no.2
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• pp.152-162
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• 2010

This study examined the effects of surround luminance on the shape of the spatial luminance contrast sensitivity function (CSF). The reduction in brightness of uniform neutral patches shown on a computer controlled display screen is also assessed to explain the change of CSF shape. Consequently, a large amount of reduction in contrast sensitivity at middle spatial frequencies can be observed; however, the reduction is relatively small for low spatial frequencies. In general, the effect of surround luminance on the CSF appears similar to that of mean luminance. Reduced CSF responses result in less power of the filtered image; therefore, the stimulus should appear dimmer with a higher surround luminance.

• The Korean Journal of Nuclear Medicine Technology
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• v.28 no.1
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• pp.23-29
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• 2024

Purpose: 99mTc-mebrofenin hepatobiliary scintigraphy (HBS) is an important and clinically useful diagnostic imaging study for detecting complications after liver transplantation. CT contrast agents due to their high atomic numbers, lead to a decrease in gamma ray count rates. This study investigated the impact of CT contrast agents on the uptake of 99mTc-mebrofenin in the liver. Materials and Methods: The quantitative HBS was performed on sixty-two liver transplantation patients (male:female=36:26), with a mean age of 59.4±6.4 years. Statistical comparison of hepatic uptake reduction ratio (HURR%) before and after the injection of CT contrast agents was performed using a paired t-test. Results: Hepatic uptake of the reduction ratio was 94.47±3.65% for the pre-CT contrast agents and 92.17±4.00% for the post-CT contrast agents. HURR% after CT contrast agent injection showed a statistically significant difference compared to before the injection (t=11.09, P<0.001). Conclusion: It will be necessary to pay attention when examining the HBS of patients with liver transplantation after the injection of CT contrast medium. It is advisable to schedule the examination on a different day to prevent residual contrast medium in the body from interfering with the quantitative evaluation of the nuclear medicine examination.

• Journal of radiological science and technology
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• v.23 no.1
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• pp.91-96
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• 2000

This work was on the reduction of exposure dose and contrast improvement by Use of Heavy Elements Filter From the result of experimental evaluation, it was found that the beam harding of X-ray was not showed in Ho and Gd, heavy elements filters, contrast to Cu and Al filters In which the harding showed. And the ratio of transit dose to surface dose and the load of X-ray tube increase in order of Al, Cu, Gd and Ho, respectively. The contrast of X-ray images using the intensifying screen and the input phosphor showed the higher value in order of Cu, Al, Gd and Ho. Therefore, in the case of using contrast media and phosphor in region of diagnostic radiology, X-ray image quality depends primarily on kVp and heavy elements filters.

• International Journal of Naval Architecture and Ocean Engineering
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• v.6 no.4
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• pp.840-866
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• 2014

Visibility in underwater images is usually poor because of the attenuation of light in the water that causes low contrast and color variation. In this paper, a new approach for underwater image quality improvement is presented. The proposed method aims to improve underwater image contrast, increase image details, and reduce noise by applying a new method of using contrast stretching to produce two different images with different contrasts. The proposed method integrates the modification of the image histogram in two main color models, RGB and HSV. The histograms of the color channel in the RGB color model are modified and remapped to follow the Rayleigh distribution within certain ranges. The image is then converted to the HSV color model, and the S and V components are modified within a certain limit. Qualitative and quantitative analyses indicate that the proposed method outperforms other state-of-the-art methods in terms of contrast, details, and noise reduction. The image color also shows much improvement.

• Journal of Digital Contents Society
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• v.5 no.1
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• pp.79-86
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• 2004

In this paper we implemented the Real Time Contrast Enhancer for image quality enhancement of moving picture. Also we proposed adaptive contrast method that use mean and variance of input video signal. The Designed the contrast Enhancer is measured in comparison with conventional picture and interfaced to 30inch TFT LCD TV of the LG Electronics.

• 한국정보디스플레이학회:학술대회논문집
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• 2005.07b
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• pp.1183-1186
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• 2005

A new reset method for high contrast ratio and reduction of the reset time is presented. In this new reset method, except the first subfield, a new reset pulse with only ramp-up period is adopted. In this reset method, from the third subfield, the background luminance generated during the reset period is theoretically zero until the first subfield of the following frame. Employing the new reset method, the dark room contrast ratio improved to 3084.7:1 from 189.1:1 of the conventional reset method. The new reset method reduced the required time for reset per subfield to 160us except the first subfield.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.9 no.7
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• pp.1594-1600
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• 2005

Recently many researches have been studied in the human vision model to solve the Wblem of the machine vision. Starting from research on the human visual system, first, we investigate the mechanisms of retina through physiological and biological evidence. In retina, input data was processed information processing that was data reduction edge detection, and emphasizing region. The processed image was recognized by region. In this paper, we proposed retinal algorithms that process data reduction and edge detection by the wavelet transform and emphasize region contrast. In experiments, the proposed model simulates processing the retina outputs in the levels and compares with outputs.

• 한국정보디스플레이학회:학술대회논문집
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• 2009.10a
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• pp.972-974
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• 2009

This paper presents smart regional contrast enhancement technique of partitioned image for local dimming backlight on small-sized mobile display to reach two goals. One is to save the power consumption, and the other to improve contrast ratio of display image. Recently new advanced method is proposed, named local dimming method, that backlight LED is positioned on backside of the display panel. So it is important to partition an image by sub blocks and then post-processing independantly. This means regional contrast enhancement. After partitioning, we compare the mean luminance(Y) value of each sub-block image with the one of original whole image. If some blocks have the mean value lower than the one of whole image, they are processed with the proposed method and others are bypassed. Simultaneously the information of the processed blocks are transferred to BLC(Backlight LED Controller). And then the supply current of each backlight LED is reduced to realize the contrast ratio enhancement and at the same time to power consumption reduction. In addition, we verify this proposed method is free from blocking artifacts.