• KSII Transactions on Internet and Information Systems (TIIS)
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• 제13권10호
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• pp.5112-5129
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• 2019

Image enhancement is a challenging problem in the field of image processing, especially low-light color images enhancement. This paper proposed a robust and comprehensive enhancement method based several points. First, the idea of bright channel is introduced to estimate the illumination map which is used to attain the enhancing result with Retinex model, and the color constancy is keep as well. Second, in order eliminate the illumination offsets wrongly estimated, morphological closing operation is used to modify the initial estimating illumination. Furthermore, in order to avoid fabricating edges, enlarged noises and over-smoothed visual features appearing in enhancing result, a multi-scale closing operation is used. At last, in order to avoiding the haloes and artifacts presented in enhancing result caused by gradient information lost in previous step, guided filtering is introduced to deal with previous result with guided image is initial bright channel. The proposed method can get good illumination map, and attain very effective enhancing results, including dark area is enhanced with more visual features, color natural and constancy, avoiding artifacts and over-enhanced, and eliminating Incorrect light offsets.

• 한국전자통신학회논문지
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• 제14권1호
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• pp.257-264
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• 2019

본 논문에서는 픽셀 기반 joint BDCP (bright and dark channel prior)와 계층적 양방향 필터를 적용하여 저 복잡도를 갖는 단일 영상 기반 안개 제거 기법을 제안한다. 픽셀 기반 joint BDCP는 기존의 패치 기반 DCP에 비해 연산량을 감소시키고, 픽셀 단위의 안개값 예측을 가능하게 하여 전달량 추정의 정확성을 높인다. 또한 에지를 보존하면서 평탄화 성능이 우수한 양방향 필터를 사용하여 전달량을 정련함으로써 후광 효과(halo effect)를 줄이고, 에지 성분에 대한 계층적 적용을 통해 반복 적용에 의한 연산량의 증가를 방지한다. 안개 성분이 포함된 다양한 영상에 대해 수행한 실험 결과는 제안하는 기법이 기존의 기법에 비해 우수한 안개 제거 성능을 보이면서 저 복잡도로 실행되어 다양한 분야에 응용될 수 있음을 나타낸다.

• 한국산학기술학회논문지
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• 제20권12호
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• pp.1-7
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• 2019

본 논문에서는 기상 및 환경조건에 영향을 받아 열화되기 쉬운 실외영상의 시인성을 개선하고 다양한 기기에 적용하기 위하여 저 복잡도의 단일 영상 안개 제거방법을 제안한다. 기존 방법에서는 거친 형태의 전달량을 추정한 후 연산량 및 메모리 요구량이 큰 정련 과정을 포함하는 반면, 제안하는 전달량 추정 방법은 에지 근처에서 픽셀 단위 dark channel과 패치 단위 dark channel을 비교함으로써 에지를 보존하는 특성이 우수하고 정련 과정이 필요하지 않아 저복잡도 전달량 추정이 가능하다. 또한, 픽셀 단위 JBDC(Joint Bright and Dark Channel)를 이용하여 각 픽셀마다 안개값을 예측함으로써 정밀한 전달량 추정과 영상의 특성에 따라 적응적인 안개 제거가 가능하다. 다양한 안개 영상에 대해 수행한 실험 결과는 제안하는 방법이 기존의 방법에 비해 적은 연산량으로 수행됨과 동시에 우수한 안개 제거 성능을 보여 실시간성이 요구되는 기기를 포함한 다양한 분야에 적용될 수 있음을 확인할 수 있다.

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 2008년도 International Symposium on Remote Sensing
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• pp.426-429
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• 2008

In this study, we propose the calibration algorithm for the solar channel (550 ${\sim}$ 900 nm) of MTSAT 1R which is the Japanese geostationary satellite launched on 26 Feb. 2005 and located at $140^{\circ}E$. We developed a method utilizing MODIS-derived BRDFs for the solar channel calibration over the bright desert area. Targets are selected based on the desert's brightness, spatial uniformity, temporal stability and spectral stability. The 6S model has been incorporated to account for directional effects of the surface using MODIS-derived BRDF parameters within the spectral interval in interest. Results based on the analysis for the period from November 2007 to June 2008 suggest that MTSAT-1R solar channel measurements have a low bias within 5%.

• 한국전자통신학회논문지
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• 제14권5호
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• pp.977-984
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• 2019

본 논문에서는 안개 성분을 포함한 실외영상의 효과적인 응용을 위하여 저 복잡도를 갖는 전달량 추정 및 픽셀 기반 JBDCP(: Joint Bright and Dark Channel Prior)를 이용한 단일 영상 기반 안개 제거 방법을 제안한다. 기존의 전달량 추정은 계산량과 메모리 요구량이 큰 정련과정을 포함하는 반면, 제안하는 안개 제거 방법은 픽셀단위 및 블록단위 dark channel 정보를 결합하여 에지 정보가 보존되는 전달량을 추정하고 복잡도를 크게 감소시킨다. 또한 픽셀 기반 JBDCP를 이용하여 영상의 각 위치마다 다른 안개값을 구함으로써 영상의 특성을 반영한 전달량 추정이 가능하다. 다양한 안개 영상에 대해 수행한 실험 결과는 제안하는 방법이 기존의 방법에 비해 저 복잡도로 실행되면서 우수한 안개 제거 성능을 보여 실시간 기기를 포함한 다양한 분야에 응용될 수 있음을 나타낸다.

• 한국멀티미디어학회논문지
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• 제23권2호
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• pp.135-145
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• 2020

Recently, deep-learning based methods for low-light image enhancement accomplish great success through supervised learning. However, they still suffer from the lack of sufficient training data due to difficulty of obtaining a large amount of low-/normal-light image pairs in real environments. In this paper, we propose an unsupervised learning approach for single low-light image enhancement using the bright channel prior (BCP), which gives the constraint that the brightest pixel in a small patch is likely to be close to 1. With this prior, pseudo ground-truth is first generated to establish an unsupervised loss function. The proposed enhancement network is then trained using the proposed unsupervised loss function. To the best of our knowledge, this is the first attempt that performs a low-light image enhancement through unsupervised learning. In addition, we introduce a self-attention map for preserving image details and naturalness in the enhanced result. We validate the proposed method on various public datasets, demonstrating that our method achieves competitive performance over state-of-the-arts.

• 대한원격탐사학회지
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• 제25권6호
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• pp.501-505
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• 2009

Quasi-linear bright features persistently appeared on ENVISAT ASAR images as well as X-SAR images along the tidal channels in Gyung-Gi Bay, Korea during the ebb tides. These features are induced by spatial backscatter variations caused by surface convergence (divergence) through the interaction between tidal currents and bathymetry. In order to validate this mechanism, a numerical tidal model simulation is performed on the realistic bathymetry with the tidal boundary conditions. The tide model reproduces the current convergence zone along the tidal channel during the ebb tides, which exactly coincides with the location of bright line features on SAR images.

• IEIE Transactions on Smart Processing and Computing
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• 제2권3호
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• pp.130-139
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• 2013

This paper proposes a new approach for enhancing digital images based on red channel information, which has the most analogous characteristics to invisible infrared rays. Specifically, a red channel in RGB space is used to analyze the image contents and improve the visual quality of the input images but it can cause unexpected problems, such as the over-enhancement of reddish input images. To resolve this problem, inter-channel correlations between the color channels were derived, and the weighting parameters for visually pleasant image fusion were estimated. Applying the parameters resulted in significant brightness as well as improvement in the dark and bright regions. Furthermore, simple contrast and color corrections were used to maintain the original contrast level and color tone. The main advantages of the proposed algorithm are 1) it can improve a given image considerably with a simple inter-channel correlation, 2) it can obtain a similar effect of using an extra infrared image, and 3) it is faster than other algorithms compared without artifacts including halo effects. The experimental results showed that the proposed approach could produce better natural images than the existing enhancement algorithms. Therefore, the proposed scheme can be a useful tool for improving the image quality in consumer imaging devices, such as compact cameras.

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 2007년도 Proceedings of ISRS 2007
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• pp.53-56
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• 2007

The Korean Geostationary satellite (COMS) to fly in year 2009 will carry a meteorological sensor from which visible channel measurements will be available. We developed a method utilizing satellite-derived BRDFs for the solar channel calibration over the bright desert area. The 6S model has been incorporated to account for directional effects of the surface using MODIS-derived BRDF parameters within the spectral interval in interest. Simulated radiances over the desert targets were compared with MODIS and SeaWiFS measured spectral radiances in order to examine the feasibility of the developed calibration algorithm. We also simulated TOA radiance over ocean targets to verify the consistency and reliability of the result. It was shown that simulated 16-day averaged radiances are in good agreement with the satellite-measured radiances within about ${\pm}5%$ uncertainty range for the year 2005, suggesting that the developed algorithm can be used for calibrating the COMS visible channel within about 5% uncertainty level.

• 기술사
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• 제12권3호
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• pp.18-22
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• 1979

"In summary, the freezing facilitty manufacturing industry has a bright prospects for further development. So followings are recommended: 1) The import restriction policy should be continued to expand the demand for the 10callT manufactured facilities, 2) Training of local people and import of advanced technologies should be encouraged 3) The capacities of the local manufacturing industry should be expanded to meet the: increasing demand for the facilities, 4) Further incentives should be affered to the freezing & cold storage sector for the repla¬cement of the worm-out facilities 5) The marketing channel of marine products should be reorganized into ""cold-chain system"" by providing a legislative supports."