• Journal of the Korea Institute of Information and Communication Engineering
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• v.16 no.7
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• pp.1477-1486
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• 2012

In this paper, we propose Multi-view CGH Making System using method of generation of virtual view-point depth image. We acquire reliable depth image using TOF depth camera. We extract parameters of reference-view cameras. Once the position of camera of virtual view-point is defined, select optimal reference-view cameras considering position of it and distance between it and virtual view-point camera. Setting a reference-view camera whose position is reverse of primary reference-view camera as sub reference-view, we generate depth image of virtual view-point. And we compensate occlusion boundaries of virtual view-point depth image using depth image of sub reference-view. In this step, remaining hole boundaries are compensated with minimum values of neighborhood. And then, we generate final depth image of virtual view-point. Finally, using result of depth image from these steps, we generate CGH. The experimental results show that the proposed algorithm performs much better than conventional algorithms.

• Proceedings of the Korean Institute of Communication Sciences Conference
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• 2006.07a
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• pp.461-461
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• 2006

• Proceedings of the Korean Institute of Communication Sciences Conference
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• 2006.07a
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• pp.281-281
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• 2006

• The Journal of Korean Institute of Communications and Information Sciences
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• v.31 no.10C
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• pp.933-941
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• 2006

In this paper, we proposed an efficient coding method for digital hologram (fringe pattern) acquired by a CCD camera or by computer generation using multi-view prediction technique and MPEG video compression standard technique. It proceeds each R, G, or B color component separately. The basic processing unit is a partial image segmented into the size of $N{\times}N$. Each partial image retains the information of the whole object. This method generates an assembled image for a row of the segmented and frequency-transformed partial images, which is the basis of the coding process. That is, a motion estimation and compensation technique of MPEG is applif:d to the reconstructed images from the assembled images with the disparities found during generation of assembled image and the original partial images. Therefore the compressed results are the disparity of eachpartial image to form the assembled image for the corresponding row, assembled image, and the motion vectors and the compensated image for each partial image. The experimental results with the implemented algorithm showed that the proposed method has NC (Normal Correlation) values about 4% higher than the previous method, by which ours has better compression efficiency. Consequently, the Proposed method is expected to be used effectively in the application areas to transmit the digital hologram data. can be identified in comparison with the previous researches and commercial IPs.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.41 no.11
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• pp.43-51
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• 2004

In this paper, we propose a high-level optical encryption system, which is tolerant with noises and cropping, by encrypting the phase-encoded CGH pattern of original image with the phase-encoded Fresnel diffraction pattern of random key images. For encryption, the phase-encoded CGH pattern of original image is multiplied by conjugate components which are the phase-encoded Fresnel diffraction patterns of random key images. The original information can be reconstructed by multiplying encrypted image by phase-encoded Fresnel diffraction pattern of random key images and performing Fourier transform of the multiplication result. The proposed system is robust to noises and cropping due to characteristics of CGH pattern and can guarantee high-level encryption by using Fresnel diffraction information. We verified the validity of proposed system by computer simulations, numerical analysis of noises and cropping effect and optical experiment.

• Korean Journal of Optics and Photonics
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• v.15 no.4
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• pp.299-308
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• 2004

We proposed more efficient encoding methods that can design a multi-channel multi-level phase only computer-generated hologram(CGH) that can reconstruct many objects simultaneously without a conjugate image. We used a fabrication technique for the pixel oriented CGH for designing the pattern of the proposed multi-channel CGH. We investigated the difference of the optical efficiency(η), mean square error(MSE) and signal-to-noise ratio(SNR) of multi-channel CGHs that were designed by three kinds of encoding methods according to the number of quantization phase levels, and we estimated the performance of the pattern of the proposed multi-channel CGH. Generally, as the number of input objects' reference patterns stored in the CGH is increased, the reconstruction quality of the CGH is degraded. But we observed through computer simulation that the diffraction efficiency of the 1-ch CGH is 70%, and those of the 2-ch, 4-ch, 8-ch CGHs are 62%, 62% and 63%. Therefore we found that the diffraction efficiencies of the multi-channel CGHs using the newly proposed encoding method are similar to that of 1-ch CGH. We implemented the CGH optically using a liquid crystal spatial light phase modulator that consisted of a PAL-SLM efficiently coupled with a XGA type LCD by an optical lens and an LD for illuminating the LCD. We discussed the output images that are reconstructed from the PAL-SLM.