• Proceedings of the Optical Society of Korea Conference
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• 1998.08a
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• pp.96-97
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• 1998

• Proceedings of the Optical Society of Korea Conference
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• 1998.08a
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• pp.228-229
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• 1998

• Proceedings of the Optical Society of Korea Conference
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• 1999.08a
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• pp.34-35
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• 1999

• Proceedings of the Optical Society of Korea Conference
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• 1999.08a
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• pp.40-41
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• 1999

• Proceedings of the Optical Society of Korea Conference
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• 1996.09a
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• pp.74-74
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• 1996

• Information Display
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• v.22 no.3
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• pp.3-14
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• 2021

• Proceedings of the Optical Society of Korea Conference
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• 2003.02a
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• pp.66-67
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• 2003

영상 정보 및 생체 패턴의 보호를 위해서 랜덤 위상 패턴을 기준파로 하는 홀로그램의 제작과 같은 암호와 방법이 사용되어 왔는데, 이런 방법들 중 가장 대표적인 것으로 이중 랜덤 위상 암호화(Double Random Phase Encryption)기법이 있다. 이중 랜덤 위상 암호화 방법은 진폭 기반의 방법과 위상 기반의 방법으로 구분한다. 암호화와 복호화의 과정은 그림 (1)에서 복호화 과정은 그림 (2)에서 보여주고 있다. (중략)

• The Journal of Korean Institute of Communications and Information Sciences
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• v.28 no.8C
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• pp.827-834
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• 2003

In this paper, we implemented an optical information security system using computer generated hologram based on the principle of interference and BaTiO$_3$that is photorefractive material. First of all, we would generate binary phase hologram which can reconstruct the original image perfectly, and regard this hologram as the image to be encrypted. And then applying the interference rule to the hologram, encrypted and reference (fkey information) images are generated. In the decrypting process, we can get an interference intensity by interfering the reference image and the encrypted image in the Mach-Zehnder interferometer. and transforming interference intensity information into phase information using LCD(liquid crystal display) and finally recover original image by inverse Fourier transforming the phase information. In this process, the Intensity information generated by interference of two images is very sensitive to external vibrations. So, we get a stable interference using the characteristic of SPPCM(self pumped phase conjugate mirror) of BaTiO$_3$that is photorefractive material. The proposed method has an advantage of double image encryption by encrypting the hologram of the image instead of original image.

• Journal of Korea Multimedia Society
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• v.14 no.3
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• pp.403-413
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• 2011

In this paper, we proposed a digital image watermarking technique using scrambled binary phase computer generated hologram in the discrete cosine transform(DCT) domain. For the embedding process of watermark. Using simulated annealing algorithm, we would generate a binary phase computer generated hologram(BPCGH) which can reconstruct hidden image perfectly instead of hidden image and encrypt it through the scramble operation. We multiply the encrypted watermark by the weight function and embed it into the DC coefficients in the DCT domain of host image and an inverse DCT is performed. For the extracting process of watermark, we compare the DC coefficients of watermarked image and original host image in the DCT domain and dividing it by the weight function and decrypt it using descramble operation. And we recover the hidden image by inverse Fourier transforming the decrypted watermark. Finally, we compute the correlation between the original hidden image and recovered hidden image to determine if a watermark exits in the host image. The proposed watermarking technique use the hologram information of hidden image which consist of binary values and scramble encryption technique so it is very secure and robust to the various external attacks such as compression, noises and cropping. We confirmed the advantages of the proposed watermarking technique through the computer simulations.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2010.11a
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• pp.302-303
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• 2010

본 논문에서는 고속으로 홀로그램을 생성하기 위해 새로운 컴퓨터 생성 홀로그램(computer-generated hologram, CGH) 수식을 제안하고, 셀 기반의 VLSI(very large scale integrated circuit) 구조를 제안하였다. 기본 CGH 수식에서 가로 또는 세로 방향의 연산 규칙을 찾아낸 후 가로 또는 세로 방향의 홀로그램 화소를 병렬적으로 구할 수 있는 수식을 유도하였다. 제안한 수식을 바탕으로 초기 파라미터 연산기(initial parameter calculator)와 업데이트-위상 연산기(update-phase calculator)로 구성된 CGH 셀의 구조를 제안하고 하드웨어로 구현하였다. 수식의 변형을 통해서 하드웨어를 간략화 시킬 수 있었고, CGH의 확장을 통해 가로 방향으로 병렬화시킬 수 있는 하드웨어 구조도 보였다. 실험에서는 하드웨어에 사용된 자원을 분석하였다. CGH 커널과 프로세서의 구조는 이전 연구에서 사용된 플랫폼을 그대로 사용하였다.