• Journal of Korea Society of Digital Industry and Information Management
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• v.9 no.2
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• pp.99-109
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• 2013

In this paper, we propose a new system which captures real depth and color information from natural scene and implemented it. Based on it, we produced stereo and multiview images for 3-dimensional stereoscopic contents and introduced the production of a digital hologram which is considered to the next-generation image. The system consists of both a camera system for capturing images which correspond to RGB and depth images and softwares (SWs) for various image processings which consist of pre-processing such as rectification and calibration, 3D warping, and computer generated hologram (CGH). The camera system use a vertical rig with two paris of depth and RGB camera and a specially manufactured cold mirror which has the different transmittance according to wavelength for obtaining images with the same view point. The wavelength of our mirror is about 850nm. Each algorithm was implemented using C and C++ and the implemented system can be operated in real-time.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.37 no.8
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• pp.67-75
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• 2000

In this paper, we proposed a new method to find dive parameters of an ellipse from the optical Hough transform (HT) results. The method employs the HT for detection of a straight line and the one-dimensional analysis of the resultant parameter domain. Using this algorithm, we simulated about the ellipses with different positions, and obtained the information of the ellipse with 94% accuracy in the worst case. To compare the simulation results with the experimental ones, we performed optical experiments using a HT Computer Generated Hologram (CGH) filter. Through the experiments, we showed that our results were very similar to the simulation results.

• Korean Journal of Optics and Photonics
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• v.17 no.6
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• pp.519-524
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• 2006

In general, the Lohmann-type binary hologram represents its amplitude and phase by using the rectangular cell. In this paper, we adapts a circular cell to represents the amplitude and phase of holograms. In order to compare the characteristics of the circular cell with the rectangular one, we analyzed the results based on the computer simulations and various optical experiments. The results show that a clearer reconstructed image can be obtained by dividing one cell into many pixels. In the case of a uniform reconstructed image, the rectangular cell is better than the circular cell. However, as for the brightness of the reconstructed image, the circular cell is better than the rectangular one.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.16 no.11
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• pp.2355-2364
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• 2012

Recently, the novel loop-up table(N-LUT) method to solve the tremendous memory problem of the conventional look-up table (LUT) method as well as to increase the generation speed of hologram patterns has been proposed. But, as the resolution of an input 3-D object is enhanced, the number of object points to be calculated for generation of its hologram pattern also increases, which results in a sharp increase of the computation time. Therefore, in this paper, a new approach for fast generation of the hologram pattern of 3-D object images is proposed by using the block redundancy feature of 3-D object images and the N-LUT method. Experimental results show that in the proposed method the number of object points and the overall computation time have been reduced by 43.3 % and 47.9 %, respectively compared to those of the conventional method for the case of the $5{\times}5$ block size. These good experimental results finally confirm the feasibility of the proposed method.

• Journal of the Institute of Electronics and Information Engineers
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• v.49 no.11
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• pp.86-94
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• 2012

In this paper we propose a hardware architecture of high-speed CGH (computer generated hologram) generation processor, which particularly reduces the number of memory access times to avoid the bottle-neck in the memory access operation. For this, we use three main schemes. The first is pixel-by-pixel calculation rather than light source-by-source calculation. The second is parallel calculation scheme extracted by modifying the previous recursive calculation scheme. The last one is a fully pipelined calculation scheme and exactly structured timing scheduling by adjusting the hardware. The proposed hardware is structured to calculate a row of a CGH in parallel and each hologram pixel in a row is calculated independently. It consists of input interface, initial parameter calculator, hologram pixel calculators, line buffer, and memory controller. The implemented hardware to calculate a row of a $1,920{\times}1,080$ CGH in parallel uses 168,960 LUTs, 153,944 registers, and 19,212 DSP blocks in an Altera FPGA environment. It can stably operate at 198MHz. Because of the three schemes, the time to access the external memory is reduced to about 1/20,000 of the previous ones at the same calculation speed.

• Journal of Broadcast Engineering
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• v.17 no.4
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• pp.695-706
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• 2012

The purpose of this paper is to propose a service system for a digital hologram video, which has not been published yet. This system assumes the existing service frame for 2-dimensional or 3-dimensional image/video, which includes data acquisition, processing, transmission, reception, and reconstruction. This system also includes the function to service the digital hologram at the viewer's view point by tracking the viewer's face. For this function, the image information at the virtual view point corresponding to the viewer's view point is generated to get the corresponding hologram. Here in this paper, only a prototype that includes major functions of it is implemented, which includes camera system for data acquisition, camera calibration and image rectification, depth/intensity image enhancement, intermediate view generation, digital hologram generation, and holographic image reconstruction by both simulation and optical apparatus. The proposed prototype system was implemented and the result showed that it takes about 352ms to generate one frame of digital hologram and reconstruct the image by simulation, or 183ms to reconstruct image by optical apparatus instead of simulation.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.12 no.10
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• pp.1751-1758
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• 2008

Digital holography interference pattern generated by a computer calculation (CGH) is one of the most expensive contents and its usage is being expanded. Thus, it is highly necessary to protect the ownership of digital hologram. In this paper a hologram-domain and a frequency-domain electronic watermarking schemes were proposed. The hologram-domain scheme was only to compare the results to the ones from frequency-domain scheme and the frequence-domain scheme used 2-dimensional against the attaks. Especially the MDWT-domain scheme was very high robustness such that th error ratio at the worst case was only 3%. Thus, we expect that it is used as a good watermarking scheme of digital hologram with high performance.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2010.11a
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• pp.21-22
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• 2010

본 논문에서는 디지털 홀로그래피 방식의 비디오 서비스를 위한 서비스 시스템의 구조를 제안하고자 한다. 실사 영상의 디지털 홀로그래피 서비스를 위해서 레이저를 이용한 광학적인 홀로그램 획득이 아닌 실사 기반의 홀로그램 획득 방법을 이용한다. 실사 기반의 홀로그램 획득 방법에는 스테레오 및 다시점 카메라, 그리고 깊이 카메라를 이용하는 것들이 포함된다. 각 카메라 시스템으로 획득된 정보는 깊이와 RGB 정보로 만들어진 후에 컴퓨터 생성 홀로그램(computer-generated hologram, CGH) 과정을 거치면서 홀로그램이 된다. 생성된 홀로그램은 SLM(spatical light modulator)를 통해서 복원되어 영상 서비스를 제공한다. 또한 디지털 홀로그램 기반의 비디오 서비스를 위한 신호처리 기법들을 종합적으로 논의하고, 마지막으로 스테레오 및 깊이 카메라 기반의 홀로그램 생성 결과들을 보인다.

• Journal of the Korean Society for Precision Engineering
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• v.33 no.10
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• pp.845-850
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• 2016

A direct laser lithography system is widely used to fabricate various types of DOEs (Diffractive Optical Elements) including lenses made as CGH (Computer Generated Hologram). However, a parametric study that uniformly and precisely fabricates the diffractive patterns on a large area (up to $200mm{\times}200mm$) has not yet been reported. In this paper, four parameters (Focal Position Error, Intensity Variation of the Lithographic Beam, Patterning Speed, and Etching Time) were considered for stabilization of the direct laser lithography system, and the experimental results were presented.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2010.07a
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• pp.108-111
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• 2010

본 논문에서는 기존의 2차원 영상/비디오 압축 기술을 홀로그램의 특성에 적합하게 변형시켜서 홀로그램 데이터를 압축하는 압축 기법을 제안하였다. 컴퓨터 생성 홀로그램(computer generated holograms, CGH) 기법을 이용해 생성한 디지털 홀로그램을 사용하였다. 본 논문에서는 전처리된 디지털 홀로그램에 대해 분할, 주파수 변환, 움직임 예측과 주파수 영역에서의 잔여영상 생성 기법을 적용하여 데이터 압축을 수행한다. 압축은 H.264/AVC, 무손실 압축기법인 BinHex와, 선형 양자화를 이용하였고, 실험 결과를 보면 제안한 데이터 압축 기법은 전체 압축률이 10:1~90:1까지 변화함에따라 25.4dB~16.5dB로 감소함을 확인할 수 있다. 그러나 시각적인 영상의 품질은 앞서 제시한 PSNR값 보다 훨씬 우수함을 확인 할 수 있다.