• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2017.11a
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• pp.193-196
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• 2017

본 논문에서는 콘트라스트 복원 기법을 통한 효과적인 비 제거 알고리즘을 제안한다. 기존의 비 제거 알고리즘은 영상에 나타난 비를 제거하는 과정에서 빗줄기로 인한 콘트라스트 감소 현상을 제거하지 못하는 단점이 존재한다. 이에 본 논문에서는 합성곱 신경망을 이용하여 빗줄기를 제거하는 기존의 알고리즘에 덧붙여 빗줄기로 인해 발생된 콘트라스트 변화량을 추정하여 복원하는 과정을 추가함으로써 기존의 알고리즘보다 효과적으로 비를 제거하는 방법을 제시한다. 실험을 통해 성능을 분석한 결과, 제안하는 알고리즘은 모든 결과 영상에 대하여 기존의 알고리즘에 비해 높은 화질 평가 수치를 나타내었으며 주관적으로도 더 선명한 결과를 보여주었다.

• Journal of Korea Multimedia Society
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• v.5 no.1
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• pp.38-46
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• 2002

In this paper, we present an adaptive contrast controller for improving the Quality of motion-picture in the video signals on the display. Using a median of image signals, we can improve the contrast according to the middle brightness, adaptively. In addition, the proposed method is useful for real-time image processing and can be composed of simpler hardware structure than other conventional methods because it does not require field and frame memory for computed data. The proposed method can be applied for video signals as well as the still image, while existing methods are confined to only the static image Also, we designed the algorithm through the VHDL, and implemented it through the FPGA. From the testing results, we see that the proposed method can effectively improve the image contrast.

• Journal of Korea Multimedia Society
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• v.5 no.6
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• pp.609-615
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• 2002

In this paper, we propose a contrast for the improvement of multi-gray scale image on display system. The proposed method distinguishes a maximum value and a minimum value in input fields or frames. By this judgement, the improvement degree of image quality is decided. This method does not require field and frame memory. Moreover, its lower hardware complexity than conventional methods make it easy to apply this method for flat panel display(FPD) which requires real-time processing. And the contrast of input gray level can be controled flexibly by varying the weight the weight value which controls the contrast range. The proposed method gives an image by controlling weighting slope selectively at intervals according to the brightness-control algorithm and the type of image in the look-up table. The function of the proposed method has been verified through Synopsys VHDL and computer simulation. And its results show that the proposed method can improve the quality of image.

• Journal of Broadcast Engineering
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• v.20 no.5
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• pp.770-773
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• 2015

The contrast of the intensity components of color images usually needs to be improved in order to enhance the visual quality of color images. However, pure color regions can be saturated due to the excessive enhancement of that color. In this paper, a new method for enhancing the visual quality of color images using saturation components in the HSI color space is proposed, and the same enhancement technique in the YCbCr color space is proposed. Computer simulations show that the proposed method provides improved visual quality compared to the conventional methods.

• Proceedings of the Korea Information Processing Society Conference
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• 2001.04b
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• pp.867-870
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• 2001

본 논문에서는 디스플레이상에서 영상 향상을 위한 다계조 콘트라스트 조절장치를 제안하였다. 제안한 방식은 추가적인 메모리를 필요하지 않고, 입력 계조 레벨에 상관없이 영상향상이 가능하다. 또한 입력 영상의 자기 정보를 고려하여 원화상의 밝기정보를 최대한 보상할 수 있으며 기존의 방식에 비해 하드웨어 구성이 간단하여 실시간 처리를 요하는 분야에 쉽게 적용 가능하고 입력되는 콘트라스 영역의 가중치 값을 사용자가 임의적으로 변화시킴으로써 콘트라스트 조정이 가능하다. 제안한 콘트라스트 조정장치는 컴퓨터 시뮬레이션을 통하여 검증하였으며, 시뮬레이션 결과 영상 향상을 확인하였다.

• Proceedings of the Acoustical Society of Korea Conference
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• spring
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• pp.395-398
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• 1999

본 연구에서는 초음파현미경에서 다중의 동작주파스를 사용하여 얻어진 영상을 합성하여 깊이분해능이 개선된 초음파영상을 복원하는 방법을 연구하였다. 실험을 위하여 중심주파수가 5MHz이고 비대역폭이 $35\%$인 초음파변환기를 사용하여 초음파현미경을 구성하였다. 시편은 알루미늄을 이용하여 표면에 깊이가 $100{\mu}m$이고 지름이 2mm인 원형결함을 제작하였다. 실험결과, 동작주파수가 5MHz인 단일 주파수를 사용하여 얻어진 영상에서 결함이 존재하는 면과 그렇지 않은 면에 대한 콘트라스트가 0.098로 나타났다. 반면에 동작주파수를 $4.4MHz\~5.6MHz$ 범위에서 200kHz씩 변화시키면서 획득한 데이터를 합성하여 얻어진 영상에서 결함이 존재하는 면과 그러하지 않은 면에 대한 영상 콘트라스트가 0.398로 나타났다. 따라서 초음파현미경에서 다중의 동작주파수를 사용한 경우, 피사체의 깊이 변화에 대한 영상의 콘트라스트가 단일주파수를 사용한 경우에 비하여 개선되어 나타났으며 깊이분해능이 향상되었다. 앞으로의 과제는 초음파현미경에서 음향렌즈의 집속도 변화에 대한 적절한 동작주파수의 동작범위와 영상의 분해능과의 관계에 대한 연구가 계속되어져야 한다고 본다.

• Journal of the Institute of Electronics and Information Engineers
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• v.53 no.6
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• pp.101-109
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• 2016

The images captured by digital still cameras or mobile phones are not always satisfactory because the devices have limited dynamic ranges compared with that of the real world. To cope with the problems, tone mapping function based methods and retinex theory based methods are studied. However, these methods generate a halo artifact or limited enhancement of global and local contrasts. The proposed method estimates illumination information used for image enhancement by optimizing a dynamic range of input image. The estimated illumination information has smoothness characteristic where the luminance is flat and does not have where the luminance changes to prevent the halo artifact. Additionally, the estimated illumination information and surrounding pixel values are considered when the tone mapping function is applied to overcome the limitations of the conventional tone mapping function approach. Experimental results show that the proposed algorithm outperforms the conventional methods on objective and subjective criteria.

• The Journal of the Acoustical Society of Korea
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• v.29 no.8
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• pp.504-508
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• 2010

In conventional diagnostic ultrasound strain imaging, when displaying strain image on a monitor, human visual characteristics are utilized such that hard regions are displayed as dark and soft regions are displayed as bright. Thus, hard regions representing tumor or cancer are displayed as dark, decreasing the contrast inside the lesion. Because the lesion area is stiff and thus displayed as dark, a method of inverting the image brightness and thereby increasing the contrast in the lesion for better diagnostic purposes is proposed wherein a postcompression signal is extended in the time domain by a factor corresponding to the reciprocal of the amount of the applied compression using a technique termed globally uniform stretching. Experiments were carried out to verify the proposed method on an ultrasound elasticity phantom with radio-frequency data acquired from a diagnostic ultrasound clinical scanner. It is found that the new method improves the contrast-to-noise ratio by a factor of up to about 1.8 compared to a conventional strain imaging method that employs a reversed gray color map without globally uniform stretching.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.39 no.6
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• pp.27-33
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• 2002

This paper proposes a method to drive an AC plasma display panel(PDP) with a significantly improved contrast ratio. In the proposed method, during the first sub-field of one frame, all PDP cells are reset by the ramp waveform, and during the other sub-fields, only the cells turned on in the previous sub-field are reset. No light is emitted during the reset period of every sub-field except the first sub-field. For a 10-bit picture, the luminance of the dark level for the proposed method is 10 times lower than that for the conventional method, in which the ramp waveform for the reset is used in every sub-field. Accordingly, the contrast ratio for the proposed method is 10 times higher than that for the conventional method. For the 10-bit picture, the measured contrast ratio was about 3080:1 for the proposed method and about 285:1 for the conventional method, resulting in 10.8 times increase in the contrast ratio. This result shows that the proposed method can realize an image with high contrast ratio.

• Electrical & Electronic Materials
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• v.2 no.2
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• pp.117-126
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• 1989

9/65/35 PLZT 세라믹을 그레인 크기에 따라 2단소성법으로 제조하여 그 전기적, 광학적특성을 관찰하고 횡모드 복굴절방식의 반사형 디스플레이소자를 제작하여 그 동작특성을 조사하였다. P-E곡선은 슬림형의 히스테리시스를 타나냈으며 그레인이 커질수록 유기분극과 광투과율은 증가하지만 복굴절율은 감소하여 디스플레이소자 구동시 콘트라스트 비가 감소 하였다. 디스플레이소자의 동작개시 전압은 1mm전극 간격에서 300V이고, $V_{(CR.Max)}$ 전압은 550V였으며 가시각도에 따른 콘트라스트 비의 비율((60.deg./90.deg.), $G_{S}$:4.mu.m)은 0.67이었다.다.