• Journal of the Korea Institute of Information and Communication Engineering
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• v.11 no.8
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• pp.1424-1433
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• 2007

In this paper, we propose a hardware architecture to generate digital hologram using the modified CGH (Computer Generated Hologram) algorithm for hardware implementation and design to FPGA (Field Programmable Gate Array) platform. After analyzing the CGH algorithm, we propose an architecture of CGH cell which efficiently products digital hologram, and design CGH Kernel from configuring CGH Cell. Finally we implement CGH Processor using CGH Kernel, SDRAM Controller, DMA, etc. Performance of the proposed hardware can be proportionally increased through simply addition of CGH Cell in CGH Kernel, since a CGH Cell has operational independency. The proposed hardware was implemented using XC2VP70 FPGA of Xilinx and was stably operated in 200MHz clock frequency. It take 0.205 second for generating $1,280{\times}1,024$ digital hologram from 3 dimensional object which has 40,000 light sources.

• ETRI Journal
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• v.44 no.1
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• pp.85-93
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• 2022

We propose an efficient method for synthesizing mesh-based realistic computer-generated hologram (CGH). In a previous nonanalytic mesh-based CGH synthesis, the angular spectrum of the two-dimensional (2D) plane is calculated using the fast Fourier transform (FFT) with the same size as the resolution of the final hologram. Because FFT increases the computation time as the size of the input matrix increases, the previous method has a problem: The higher the resolution of the hologram, the greater the computational load, thereby delaying synthesis time. In this study, when calculating the angular spectrum of the 2D plane in mesh-based CGH synthesis, we propose a method to calculate the angular spectrum by defining the 2D plane with an arbitrary size smaller than the resolution of the final hologram. The resolution adjustment method reduces the computation time and can be applied to occlusion culling and texturing for the realistic effect of mesh-based CGH. We describe the principle, error analysis, application of realistic effect, and experimental results of the proposed method.

• Journal of Korea Society of Digital Industry and Information Management
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• v.9 no.1
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• pp.151-163
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• 2013

Recently the attention on digital hologram that is regarded as to be the final goal of the 3-dimensional video technology has been increased. Digital hologram is calculated by modeling the interference phenomenon between an object wave and a reference wave. The modeling for digital holograms is called by computer generated hologram (CGH) Generally, CGH requires a very large amount of calculation. So if holograms are generated in real time, high-speed method should be needed. In this paper, we analyzed CGH equation, optimized it for mapping general purpose graphic processing unit (GPGPU), and proposed a optimized CGH calculation technique for GPGPU by resource allocation and various experiments which include block size changing, memory selection, and hologram tiling. The implemented results showed that a digital hologram that has $1,024{\times}1,024$ resolution can be generated during approximately 24ms, using 1K point clouds. In the experiment, we used two GTX 580 GPGPU of nVidia Inc.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.16 no.4
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• pp.713-720
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• 2012

Recently, holography has received much attention as the next generation visual technology. Hologram is obtained by the optical capturing, but in recent years it is mainly produced by the method using computer. This method is named by computer generated hologram (CGH). Since CGH requires huge computational amount, if it is implemented by S/W it can't work in real time. Therefore it should use FPGA or GPU for real time operation. If it is implemented in the type of H/W, it can't obtain the same quality as S/W due to the bit limitation of the internal system. In this paper, we analyze the bit width for minimizing the degradation of the hologram and reducing more hardware resources and propose guidelines for H/W implementation of CGH. To do this, we performs fixed-points simulations according to main internal variables and arithmetics, analyze the numerical and visual results, and present the optimal bit width according to application fields.

• Journal of information and communication convergence engineering
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• v.11 no.4
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• pp.282-287
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• 2013

A real-time digital holographic display is the core technology for the next-generation 3DTV. Holographic display requires a considerably large amount of calculation. If generating a large number of digital holograms is intended, the amount of calculation and the time required increase exponentially. This is a significant obstacle in a real-time hologram service. This paper proposes an algorithm that increases the speed of generating a Fresnel hologram by using a recursive addition operation covering the entire coordinate array of a digital hologram. The 3D object designed to calculate the digital hologram uses a depth-map image produced by computer graphics. The proposed algorithm is a technique that performs the computer-generated holography (CGH) operation with only recursive addition of all of the hologram's coordinates by analyzing the regularity between the 3D object and the digital hologram coordinates. The experimental results show that the proposed algorithm increases the operation speed by 70% over the technique using the conventional CGH equation and by more than 30% over the previously proposed recursive technique.

• Korean Journal of Optics and Photonics
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• v.19 no.5
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• pp.360-364
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• 2008

The diffraction efficiencies of gratings are affected by the inner structure which is determined by modulation type. CGH (Computer generated Hologram) basically uses the principles of a diffraction grating. As like as the diffraction gratings the patterns recorded in the CGH are different according to modulation methods which result in the performances of the reconstructed images. In this paper, on this fact CGHs are recorded according to sinusoidal and rectangular modulation methods and the characteristics of reconstructed images are analyzed. Also the reconstruction performances of the amplitude and phase, phase-only and binary phase CGH are analyzed.

• Journal of the Korean Physical Society
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• v.73 no.11
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• pp.1657-1662
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• 2018

A null test method which relies on a computer generated hologram (CGH) is widely used to measure a large aspheric surface. For precise measurements of the surface shape of an aspheric optics, the CGH must precisely generate a wavefront that can fit on the ideal surface shape of the aspheric optics. If fabrication errors arise in the CGH, an unwanted wavefront will be generated and the measuring result will lack trustworthiness. Thus far, there has been limited research on wavefronts generated by CGH using only linear-type binary grating models. In this study, a theoretical error model of a circular-type zone plate, the most commonly used types for CGH patterns, is suggested. The proposed error model is checked by simulations and experiments.

• Journal of the Optical Society of Korea
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• v.18 no.6
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• pp.698-705
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• 2014

We propose a new development for calculating a computer-generated hologram (CGH) through the use of multiple general-purpose graphics processing units (GPGPUs). For optimization of the implementation, CGH parallelization, object point tiling, memory selection for object point, hologram tiling, CGMA (compute to global memory access) ratio by block size, and memory mapping were considered. The proposed CGH was equipped with a digital holographic video system consisting of a camera system for capturing images (object points) and CPU/GPGPU software (S/W) for various image processing activities. The proposed system can generate about 37 full HD holograms per second using about 6K object points.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2020.07a
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• pp.571-572
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• 2020

3D 디스플레이 산업에 있어서 홀로그램의 상용화는 여전히 많은 문제점을 가지고 있다. Computer Generated Hologram(CGH)은 홀로그램 분야 중에서도 3D 물체를 생성하는데 여러 가지 강점을 가지고 있지만 큰 해상도를 가진 CGH를 생성하는데 많은 연산시간이 걸려 상업화에 걸림돌이 되고 있다. 이 논문에서는 이를 해결하기 위하여 오목 렌즈 함수를 이용한 초 고해상도 CGH를 생성하는 알고리즘을 이용하여 초 고해상도 홀로그램을 생성하는 방법을 제안하였다. 초 고해상도 CGH를 생성하기 위하여 필요한 일반적인 방법으로 실제로 계산해야 될 CGH의 크기는 4 메가픽셀(2k X 2k) 수준의 저해상도로서, 저사양의 컴퓨터로서도 충분히 빠르고 부담 없이 계산해낼 수 있는 사이즈이다. 생성된 CGH로 Array를 형성한 후, 해당 위치에 알맞은 임의의 오목 렌즈 함수를 곱해줌으로서 임의의 크기 및 복원 거리를 가지는 초고해상도 CGH를 생성할 수 있음을 확인하였다.

• 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.