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Automatic Frame Composition Using Histogram Based Graph Cut
Daehee Kim,Hyungtae Kim,Jinho Park,Donggyun Kim,Joonki Paik 보안공학연구지원센터 2015 International Journal of Multimedia and Ubiquitous Vol.10 No.1
In this paper, we present an automatic background composition method using histogram-based graph cut. The proposed method consists of four steps: i) initial label map generation, ii) label map update, iii) object extraction by segmentation, and iv) dynamic background composition. Since the proposed method can minimize the user interaction for generating the initial label map and updating, it is suitable for simple interaction using a low-speed processor and limited memory space. Experimental results show that the proposed method provides better segmentation results compared with existing state-of-the-art methods with significantly reduced computational complexity. The proposed automatic object segmentation and background composition method can be applied to video editing, video conference, and video contents creation using low-cost mobile devices such as smart phones, smart TVs, and tablet PCs.
Inter-Conversion Matrix for Transcoding Block DCT and DWT-Based Compressed Images
Kim, Donggyun,Lim, Sanghee,Paik, Joonki The Institute of Electronics and Information Engin 2014 IEIE Transactions on Smart Processing & Computing Vol.3 No.3
This study derived the inter-conversion matrices, which can be used in heterogeneous image transcoding between the compressed images using different transforms, such as the $8{\times}8$ block discrete cosine transform (BDCT) and the one-level discrete wavelet transform (DWT). Basically, to obtain the one-level DWT coefficients from $8{\times}8$ BDCT, inverse BDCT should be performed followed by forward DWT, and vice versa. On the other hand, if the proposed interconversion approach is used, only one inter-conversion matrix multiplication makes the corresponding transcoding possible. Both theoretical and experimental analyses showed that the amount of computation of the proposed approach decreases over 20% when the inter-conversion matrices are used under specific conditions.
A Study on Intention Exchange-based Ship Collision Avoidance by Changing the Safety Domain
Donggyun Kim 해양환경안전학회 2019 海洋環境安全學會誌 Vol.25 No.3
Even if only two ships are encountered, a collision may occur due to the mistaken judgment of the positional relationship. In other words, if an officer does not know a target ship’s intention, there is always a risk of collision. In this paper, the experiments are conducted to investigate how the intention affects the action of collision avoidance in cooperative and non-cooperative situations. In non-cooperative situation, each ship chooses a course that minimizes costs based on the current situation. That is, it always performs a selfish selection. In a cooperative situation, the information is exchanged with a target ship and a course is selected based on this information. Each ship uses the Distributed Stochastic Search Algorithm so that a next-intended course can be selected by a certain probability and determines the course. In the experimental method, four virtual ships are set up to analyze the action of collision avoidance. Then, using the actual AIS data of eight ships in the strait of Dover, I compared and analyzed the action of collision avoidance in cooperative and non-cooperative situations. As a result of the experiment, the ships showed smooth trajectories in the cooperative situation, but the ship in the non-cooperative situation made frequent big changes to avoid a collision. In the case of the experiment using four ships, there was no collision in the cooperative situation regardless of the size of the safety domain, but a collision occurred between the ships when the size of the safety domain increased in cases of non-cooperation. In the case of experiments using eight ships, it was found that there are optimal parameters for collision avoidance. Also, it was possible to grasp the variation of the sailing distance and the costs according to the combination of the parameters, and it was confirmed that the setting of the parameters can have a great influence on collision avoidance among ships.
A Study on Intention Exchange-based Ship Collision Avoidance by Changing the Safety Domain
Kim, Donggyun The Korean Society of Marine Environment and safet 2019 海洋環境安全學會誌 Vol.25 No.3
Even if only two ships are encountered, a collision may occur due to the mistaken judgment of the positional relationship. In other words, if an officer does not know a target ship's intention, there is always a risk of collision. In this paper, the experiments are conducted to investigate how the intention affects the action of collision avoidance in cooperative and non-cooperative situations. In non-cooperative situation, each ship chooses a course that minimizes costs based on the current situation. That is, it always performs a selfish selection. In a cooperative situation, the information is exchanged with a target ship and a course is selected based on this information. Each ship uses the Distributed Stochastic Search Algorithm so that a next-intended course can be selected by a certain probability and determines the course. In the experimental method, four virtual ships are set up to analyze the action of collision avoidance. Then, using the actual AIS data of eight ships in the strait of Dover, I compared and analyzed the action of collision avoidance in cooperative and non-cooperative situations. As a result of the experiment, the ships showed smooth trajectories in the cooperative situation, but the ship in the non-cooperative situation made frequent big changes to avoid a collision. In the case of the experiment using four ships, there was no collision in the cooperative situation regardless of the size of the safety domain, but a collision occurred between the ships when the size of the safety domain increased in cases of non-cooperation. In the case of experiments using eight ships, it was found that there are optimal parameters for collision avoidance. Also, it was possible to grasp the variation of the sailing distance and the costs according to the combination of the parameters, and it was confirmed that the setting of the parameters can have a great influence on collision avoidance among ships.
Block-Overlapped Image Restoration with Space-Variant Motion Blur
Donggyun Kim,Sungjun Yim,Joonki Paik 대한전자공학회 2007 ITC-CSCC :International Technical Conference on Ci Vol.2007 No.7
Various image restoration methods have been proposed for removing space-variant image degradation. Most image restoration methods, which are developed to remove space-invariant degradation, cannot efficiently deal with space-invariant characteristics of natural image degradation. In this paper, we address a novel method to improve motion deblurring performance in the spacevariant manner. The first step in the proposed method processes an image overlapped small blocks. In each block, we detect frequency characteristic. We can then estimate point spread function (PSF) by combining all the information we found from the first step. Experimental results show the proposed method can efficiently remove space-variant motion blur without undesired artifacts.
The inverses of tails of the Riemann zeta function
Kim, Donggyun,Song, Kyunghwan Springer International Publishing 2018 Journal of inequalities and applications Vol.2018 No.1
<P>We present some bounds of the inverses of tails of the Riemann zeta function on [FORMULA OMISSION] and compute the integer parts of the inverses of tails of the Riemann zeta function for [FORMULA OMISSION], and [FORMULA OMISSION].</P>
Extended fisheye lens model for practical geometric correction and image enhancement.
Kim, Donggyun,Park, Jinho,Paik, Joonki Optical Society of America 2014 Optics letters Vol.39 No.21
<P>An extended fisheye lens model is presented to control the size ratio between the distorted and virtually undistorted images based on orthographic projection. The optimum size ratio is derived to correct the barrel distortion of a fisheye lens so that the maximum amount of the peripheral region is reconstructed with the minimum visual distortion. The geometric correction generates an aliasing artifact in the central region and a jagging artifact in the peripheral region. Based on the proposed lens model, a novel image enhancement algorithm is also presented to remove the aliasing and jagging artifacts in the geometrically corrected image. Experimental results demonstrate that the proposed enhancement method outperforms existing methods in the sense of objective and subjective measures.</P>
Donggyun Kim,Jinho Park,Junghoon Jung,Taechan Kim,Joonki Paik IEEE 2014 IEEE transactions on consumer electronics Vol.60 No.1
<P>In this paper, a novel image enhancement system for a wide-angle lens camera is presented. The proposed system consists of; i) lens distortion correction using space-varying interpolation kernels and ii) image restoration based on the local self-similarity. The correction process for the geometric distortion produced by a wide-angle lens results in radial distortion artifacts caused by non-linear resampling. To reduce such artifacts, the proposed algorithm uses space-varying interpolation kernels derived from the lens calibration data. The corrected image is further enhanced using self-example-based image restoration. Experimental results demonstrate the proposed method can correctly remove the geometric distortion and further enhance the quality of the radially interpolated image.</P>