• The Journal of Korean Institute of Communications and Information Sciences
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• v.33 no.3C
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• pp.255-261
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• 2008

Conventional look-up table(LT) has gained a lot of speed increase in generation of digital holograms for 3D objects, but it has required an enormous memory size of the LT. In this paper, a novel approach to dramatically reduce the size of the conventional LT, still keeping its advantage of fast computational speed is proposed, which is called here a N-LT(novel look-up table) method. In the proposed method, only the fringe patterns of the center points on each image plane are pre-calculated, called elemental fringe patterns and stored in the look-up table. Then, the fringe patterns for other object points on each image plane can be obtained by simply shifting this pre-calculated elemental fringe pattern according to the displaced values from the center to those points and adding them together. Some experimental results revealed that the computational speed and the required memory size of the proposed approach are found to be 48.7 times faster than that of the ray-tracing method and 217 times smaller than that of the conventional LT method, respectively.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.30 no.11C
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• pp.1053-1059
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• 2005

The computer generated hologram (CGH) designs and produces digital information for generating 3-D (3-Dimension) image using computer and software instead of optically-sensed hologram of light interference, and it can synthesis a virtual object which is physically not in existence. Since digital hologram includes an amount of data as can be seen at the process of digitization, it is necessary that the data representing digital hologram is reduced for storing, transmission, and processing. As the efforts that are to handle hologram with a type of digital information have been increased, various methods to compress digital hologram called by fringe pattern are groped. Suitable proposal is encoding of hologram. In this paper, we analyzed the properties of CGH using tools of frequency transform, assuming that a generated CGH is a 2D image by introducing DWT that is known as the better tool than DCT for frequency transform. The compression and reconstruction result which was extracted from the wavelet-based codecs illustrates that it has better properties for reconstruction at the maximum 2 times higher compression rate than the Previous researches of Yoshikawa[2] and Thomas[3].

• Electronics and Telecommunications Trends
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• v.31 no.3
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• pp.50-59
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• 2016

Light-field(LF) 기술은 자연스러운 완전 입체영상을 재현하면서도 홀로그램에 앞서 실현 가능한 기술로 알려져 있으며, 이에 대한 기술개발이 국내외에서 활발히 진행되고 있다. LF 기술은 카메라로 빛의 세기와 방향 정보를 획득 후 디스플레이로 그대로 재현함으로써 시각적으로 왜곡이 없는 완전 입체의 실감영상을 시청하게 하는 것이다. 조밀한 시점영상, 깊이영상의 제공으로 3D 단말 분야뿐만 아니라, 초점조절 기능을 통해 다양한 2D 응용 기술로 활용할 수 있다. LF 기술은 대형 디스플레이에서 완전 입체영상 제공을 목적으로 개발이 시작되었지만, 최근에는 모바일 단말, HMD와 같은 개인용 단말에 LF 기술을 적용하기 위한 기술개발이 시도되고 있다. 본고에서는 LF 카메라 및 단말 기술의 원리와 개발동향에 대해 살펴보고자 한다.

• Journal of the Korean Institute of Telematics and Electronics D
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• v.34D no.5
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• pp.67-74
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• 1997

In this paper, we psresent a new scheme to synthetically generate a HPO digital hologram for a three-dimensional image that is modelled as the horizontally stacked two-dimensional images. The proposed method transforms a lightwave field into the angular spectrum of planewaves, which enables this method to use FFT routines, rather than using numerous arithmetic calculations. Hence, this method may be able to not only lead to the dramatically less computation but provide relatively excellent performances due to the phase error-free transformation. We present sampling constraints and implementaton procedure to obtian a hololine for each image and also point out the necessity of interpolation. Simulatioj results are presented to show the comparison with the conventional method in terms of computation time and performances, including the behaviors resulting form the different selection of parameter values to be used in the interpolations.

• Proceedings of the IEEK Conference
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• 2006.06a
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• pp.415-416
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• 2006

In this paper, we proposed a new coding technique of digital hologram video using 3D scanning method and video compression technique. The proposed coding consists of capturing a digital hologram to separate into RGB color space components, localization by segmenting the fringe pattern, frequency transform using $M{\tiems}N$ (segment size) 2D DCT (2 Dimensional Discrete Cosine Transform) for extracting redundancy, 3D scan of segment to form a video sequence, motion compensated temporal filtering (MCTF) and modified video coding which uses H.264/AVC.

• Journal of Broadcast Engineering
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• v.26 no.3
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• pp.296-307
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• 2021

A digital hologram (DH) is an ultra-high value-added video content that includes 3D information in 2D data. Therefore, its intellectual property rights must be protected for its distribution. For this, this paper proposes a watermarking method of DH using a deep neural network. This method is a watermark (WM) invisibility, attack robustness, and blind watermarking method that does not use host information in WM extraction. The proposed network consists of four sub-networks: pre-processing for each of the host and WM, WM embedding watermark, and WM extracting watermark. This network expand the WM data to the host instead of shrinking host data to WM and concatenate it to the host to insert the WM by considering the characteristics of a DH having a strong high frequency component. In addition, in the training of this network, the difference in performance according to the data distribution property of DH is identified, and a method of selecting a training data set with the best performance in all types of DH is presented. The proposed method is tested for various types and strengths of attacks to show its performance. It also shows that this method has high practicality as it operates independently of the resolution of the host DH and WM data.

• Proceedings of the Optical Society of Korea Conference
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• 2009.02a
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• pp.167-168
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• 2009

We propose a new computing method for Fourier hologram of 3D objects captured by lens array. Fourier hologram of the two objects which positioned at different distances can be calculated using multiple orthographic view images. The size of the Fourier hologram is in proportion to the number of the orthographic view images. By repeating the orthographic view images, the size of the Fourier hologram can be increased. The principle is verified by numerically reconstructing the hologram which is synthesized from the orthographic images captured optically.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2018.05a
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• pp.281-282
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• 2018

In this paper, we will analyze the domestic and overseas technology development trends of the multi-view video content Depth Map.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2018.06a
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• pp.294-296
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• 2018

최근 디지털 홀로그래피는 3차원 영상을 획득, 처리 및 재생을 하지만, 디스플레이 전자 소자 특성에 의한 시야각이 작아서 사용자의 관찰 가능한 시역이 제한적인 단점이 있으며, 따라서 복원된 입체 영상과 사용자 사이에 상호작용 서비스 제공이 용이하지 않는 한계를 지니고 있다. 본 논문에서 우리는 $360^{\circ}$ 전방향 (1,024 시점)의 홀로그래픽 3D 콘텐츠를 FFT 알고리즘을 이용하여 생성하고, 이 콘텐츠를 디스플레이할 수 있으면서 동시에 이 콘텐츠와 사용자 간 상호작용이 가능한, 광시야각 (${\pm}60^{\circ}$) 홀로그래픽 디스플레이 시스템의 설계 및 제작한 결과를 실증한다.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.43 no.10 s.352
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• pp.22-27
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• 2006

In this paper, we propose a method that can generate a computer-generated hologram (CGH) from the depth stream and color image outputs provided by an active sensor add-on camera. Distinguished from an existing holographic display system that uses a computer graphic model to generate CGH, this method utilizes a real camera image including a depth information for each object captured by the camera, as well as color information. This procedure consists of two steps that the acquirement of a depth-annotated image of real object, and generation of CGH according to the 3D information that is extracted from the depth cue. In addition, we display the generated CGH via a holographic display system. In experimental system we reconstruct an image made from CGH with a reflective LCD panel that had a pixel-pitch of 10.4um and resolution of 1408X1050.