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An Optimal Low Dynamic Range Image Generation Method Using a Neural Network
Park, Kwanwoo,Yu, Soohwan,Park, Seonhee,Lee, Sangkeun,Paik, Joonki IEEE 2018 IEEE transactions on consumer electronics Vol.64 No.1
<P>This paper presents a neural network-based method to generate multiple images with different exposures from a single input low dynamic range (LDR) image for improved high dynamic range (HDR) imaging. The proposed algorithm consists of three steps: 1) 2-D histogram estimation; 2) neural network-based LDR images estimation; and 3) generation of an optimal set of differently exposed images. The proposed method first generates image features by estimating a patched-based 2-D histogram. The extracted features are used in an input layer of the neural network, which plays a role to select an optimal set of LDR images. A set of LDR images is generated using a curvature-based contrast enhancement method. Experimental results show that the proposed method can generate an optimal set of LDR images using neural network and provide improved HDR images. In addition, the proposed method can be implemented as a preprocessing step in most existing HDR frameworks. The proposed HDR approach is considered as a single-input method that gives almost the same performance to multiple image-based HDR method.</P>
Low-light image restoration using bright channel prior-based variational Retinex model
Park, Seonhee,Moon, Byeongho,Ko, Seungyong,Yu, Soohwan,Paik, Joonki Springer (Biomed Central Ltd.) 2017 EURASIP journal on image and video processing Vol.2017 No.-
<P>This paper presents a low-light image restoration method based on the variational Retinex model using the bright channel prior (BCP) and total-variation minimization. The proposed method first estimates the bright channel to control the amount of brightness enhancement. Next, the variational Retinex-based energy function is iteratively minimized to estimate the improved illumination and reflectance using the BCP. Contrast of the estimated illumination is enhanced using the gamma correction and histogram equalization to reduce a color distortion and noise amplification. Experimental results show that the proposed method can provide the better restored result than the existing methods without unnatural artifacts such as noise amplification and halo effects near edges.</P>
Low-light image enhancement using variational optimization-based retinex model
Seonhee Park,Soohwan Yu,Byeongho Moon,Seungyong Ko,Joonki Paik IEEE 2017 IEEE transactions on consumer electronics Vol.63 No.2
<P>This paper presents an optimization-based low-light image enhancement method using spatially adaptive l(2)-norm based Retinex model. The proposed method adaptively enforces the regularization parameter using the spatially adaptive weight map, which is generated using the bright channel prior (BCP) and local variance map. Since the proposed weight map assigns the smaller weight value at the bright and edge region, the proposed method can perform weak noise reduction to preserve the edges and textures. In addition, the simplified version of the proposed method is presented using the FFT and quantized weight values for the application to consumer devices. Experimental results show that the proposed method can provide better enhanced result without the l(2)-norm minimization artifacts at the low computational cost.</P>
( Seonhee Park ),( Jae Young Leem ) 대한금속재료학회(구 대한금속학회) 2016 대한금속·재료학회지 Vol.54 No.4
ZnO thin films were spin-coated onto a Zn seed layer that was deposited on a quartz substrate by thermal evaporation. This was found to enhance the structural and optical properties of the resulting ZnO thin film, with a particular improvement in its optical transmittance. Furthermore, by varying the temperature at which the Zn seed layer was thermally annealed, a temperature of 100℃ was identified as being optimal to ensure a maximum increase in the crystallinity and optical properties of a ZnO thin film. On the basis of these results, it is proposed that the use of a thermally annealed Zn seed layer is an effective means of achieving high-quality ZnO thin films.
Contrast Enhancement for Low-light Image Enhancement: A Survey
Seonhee Park,Kiyeon Kim,Soohwan Yu,Joonki Paik 대한전자공학회 2018 IEIE Transactions on Smart Processing & Computing Vol.7 No.1
In this paper, various contrast and low-light image enhancement methods are described and classified into three categories: i) histogram-based, ii) transmission map–based, and iii) retinexbased. The performance of the image enhancement algorithms is evaluated by comparing the resulting images using low-contrast and low-light images acquired under different illumination conditions. Various image enhancement algorithms are analyzed for both performance and efficiency. The described image enhancement algorithms can be applied to various visual surveillance or video analytics applications with low-light, low-contrast video input.
우리나라 16개 시도의 주택가격과 주택담보대출 간의 연계성
박선희 ( Seonhee Park ),황진영 ( Jinyoung Hwang ) 한국재정정책학회 2017 財政政策論集 Vol.19 No.4
The purpose of this study is to investigate the impacts of the level and change rate of housing prices (both owner and rental housing prices) on the change rate of mortgage loans, using the balanced panel data over the period 2008∼2015. The empirical results are summarized as follows. First of all, the change rate of housing price has a statistically significant and positive impact on the change rate of the mortgage loan of deposit bank, regardless of the model specifications. However, the statistical significances of the estimation coefficients of housing price itself depend on the estimation models. This implies that the impact of the change rate of housing price on the deposit bank’s mortgage loan may be more significant compared with that of housing price itself. In addition, the level and change rate of owner housing price are estimated to have negative and positive impacts on the change rate of mortgage loan in non-bank depository institutions, respectively, regardless of the estimation methods. However, both the level and change rate of the rental housing price does not have significant impacts on the change rate of mortgage loan in non-bank depository institutions. It suggests that the higher mortgage value of the house, the easier it will be to get a mortgage loan from deposit banks rather than non-bank depository institutions.
Lee, Seonhee,Park, Juhwan,Park, Je-Kyun Elsevier 2018 Sensors and actuators. B, Chemical Vol.273 No.-
<P><B>Abstract</B></P> <P>The rapid on-site detection of organophosphate compounds such as nerve agents and pesticides is essential due to their lethal effect, which irreversibly inhibits the activity of acetylcholinesterase (AChE). In this study, we demonstrate a foldable paper-based analytical device (PAD) that is capable of detecting an AChE inhibitor in a semiquantitative manner. An angle-based readout of the yellow area in the ring-type paper channel was used for the semiquantitative analysis with the naked eye. The color of the paper channel was changed to yellow as a result of oxidized cerium oxide nanoparticles by hydrogen peroxide produced from the enzymatic reactions. All reagents required for enzyme reactions were preadsorbed on the pop-up card shaped PAD to minimize the manual steps for dealing with multiple reagents for sequential enzyme reactions. As a proof of concept, we were able to semiquantitatively analyze a nerve agent simulant called dimethyl methylphosphonate (DMMP), one of the AChE inhibitors, by simply reading the angle of the yellow area in the paper channel. The foldable PAD proposed here would serve as a valuable tool that allows unskilled people to semiquantitatively detect AChE inhibitors in the field, including nerve agents and organophosphate pesticides.</P> <P><B>Highlights</B></P> <P> <UL> <LI> A foldable 3D paper device was designed for sequential enzyme reactions. </LI> <LI> Semiquantitative analysis with the naked eye was achieved by an angle-based readout. </LI> <LI> All reagents required for enzyme reactions were preadsorbed on the paper device. </LI> <LI> Dimethyl methylphosphonate as one of the AChE inhibitors was analyzed. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>