• Journal of the Korea Society of Computer and Information
• /
• v.8 no.3
• /
• pp.94-99
• /
• 2003

In this paper, a rotation invariant fingerprint identification system is implemented using the circular harmonic filter and phase only correlator. We extracted the phase component from input fingerprint image and correlate it with the circular harmonic filter of the reference fingerprint image by POC. The input image is obtained using a prism operating in the internal full reflection mode. Then the input image is transformed to two dimensional Fourier spectrum in optical way and the phase component is extracted using a digital system from the spectrum. Because composed of the optical system and digital algorithm, the proposed system has the advantages of the two technologies such as realtime parallel processing property of the optics and the flexibility of the digital system.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.19 no.2
• /
• pp.372-378
• /
• 2015

Smoke generated from business establishments and factories will not only cause air pollution but also have a significant impact on the human body. Generally, the most common method for measuring the turbidity of the plume generated from the stack is a method of observing by the transmissometer mounted in the chimney or Method 9 from the US EPA(Environmental Protection Agency) which is a visual method of determining plume turbid emitted from stationary sources. However, these methods need a lot of cost to build and maintain. In this paper, we build a plume turbidity measurement module programs using a digital camera. We design and implement a module which acquires the pictures of the plume using a digital camera and measures the turbidity of it using the DOM(Digital Optical Method). In addition, we demonstrate the excellence by comparing and analyzing implemented module and other methods.

• Korean Journal of Optics and Photonics
• /
• v.15 no.2
• /
• pp.183-189
• /
• 2004

As high quality digital cameras become readily available, digital cameras are being used not only for simple picture recording but also as information storing media in various fields. However, due to the fact that the spectral responses of the camera sensors are different from color matching functions of the CIE standard observer, the color can not be measured using these cameras. This study shows a method for converting camera image to sRGB image, in which color information is preserved. The transfer matrix between camera output signals and CIE stimulus values was determined using a multiple regression method with Macbeth ColorChecker as target colors. The CIE stimulus values for camera output signals can be mapped with a transfer matrix, and these values are converted to sRGB signals. As the result of testing a Kodak DC220 digital camera, the average color difference of Macbeth ColorChecker between true and displayed colors was 2.1 $\Delta$ $E_{ab}$ $^{*}$.$^{*}$.

• Proceedings of the Korean Society of Broadcast Engineers Conference
• /
• 2010.07a
• /
• pp.224-226
• /
• 2010

컴퓨터 생성 홀로그램(computer-generated hologram, CGH) 기법은 광학 신호들을 근사화한 후 PC에서 수학적인 연산으로 디지털 홀로그램을 생성하는 기술이다. 본 논문에서는 CGH 기법을 하드웨어로 구현할 경우 완벽한 병렬처리와 파이프라이닝이 가능하도록 연산식을 최적화하는 방법을 제안한다. 제안한 방법은 홀로그램의 이전 좌표에서 계산된 값에 일정한 값을 더하여 홀로그램을 생성하는 반복가산 기법의 일반항을 분석하여 하드웨어에 최적화된 수식으로 변형하는 것이다. 최적화된 수식의 경우 현재 좌표의 홀로그램을 계산하기 위해 이전 좌표에서 연산되었던 결과값을 기다렸다 이용하지 않기 때문에 실시간 디지털 홀로그래피를 위한 전용 하드웨어의 설계에 적합할 것이다.

• Proceedings of the Korean Society of Broadcast Engineers Conference
• /
• 2013.06a
• /
• pp.83-84
• /
• 2013

홀로그래픽 스테레오그램은, 양안 스테레오스코픽 영상들을 레이저 기준파와 간섭시켜 생성된 홀로그래픽 패턴을 감광매질인 홀로그래픽 필름에 기록한 후, 이를 다시 광학적 회절을 이용하여 3차원 영상으로 재현하는 3차원 디스플레이의 한 방법이다. 본 논문에서는 다시점의 full-color, full-parallax 영상을 디지털 방식의 스테레오그램으로 제작하여 3차원 입체 영상으로 재현하기 위한 기록 시스템에서, 기록 매질인 홀로그래픽 필름 면에서의 영상을 고해상도 영상 센서를 이용하여 직접 획득하고, 이 영상 정보를 분석하여 광축을 제어함으로써, 왜곡없는 최적의 호겔을 형성하여 높은 회절 효율을 갖는 스테레오그램을 제작하기 위한 방법 및 장치에 대한 연구개발 결과를 기술하였다.

• Korean Journal of Optics and Photonics
• /
• v.11 no.2
• /
• pp.67-72
• /
• 2000

A lot of varIOUS studies are taking advantage of annular masks or various pupil filters to design optical systems such as a digital versatile disc (DVD) pick up head and precise scanning microscopy that have the superresolution beyond the diffraction limit. We considered both annular mask and pupil filter for the superresolution system. Since image quality is a function of annular width, position and modulation amount, we computel'lzed the optimized condition for the phase modulation and mvestigated the variation of lhe center peak: intensity for the phase modulated system From tills result, we were able to detenrune the best conditions for the annular apodizer, wluch give the maximum value of the center peak intensity_ We made especially sure that the phase modulated system have an excellent compensation for spherical aberration as it lllcreases. eases.

• The Journal of the Korea institute of electronic communication sciences
• /
• v.13 no.2
• /
• pp.411-418
• /
• 2018

This paper presents a novel three-dimensional (3D) object encryption scheme by combining the use of the virtual optics and the chaotic sequence. A virtual 3D object is digitally produced using a two-dimensional (2D) elemental image array (EIA) created with a virtual pinhole array. Then, through a logistic mapping of chaotic sequence, a final encrypted video can be produced. Such method converts the value of a pixel which is the basic information of an image. Therefore, it gives an improved encryption result compared to other existing methods. Through computational experiments, we were able to verify our method's feasibility and effectiveness.

• Korean Journal of Optics and Photonics
• /
• v.22 no.5
• /
• pp.214-218
• /
• 2011

In this paper we have applied self-reference hologram to DHM (digital holography microscopy) to remove phase aberration. We have constructed an off-axis reflection- type digital holography microscope. We have extracted a low spatial frequency hologram from the conjugated hologram and used it as a reference hologram. Experimentally we show that distortion of image and aberration of phase in a measurement system are removed using the self-reference hologram.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.34 no.6C
• /
• pp.604-610
• /
• 2009

This paper propose a digital watermarking method for digital contents which satisfies both the invisibility and the robustness to attacks to prohibit counterfeiting, modification, illegal usage and illegal re-production of video contents. This watermarking algorithm insert a watermark(digital hologram) by generated using Fresnel transform which improve the robustness. The inserting positions of the watermark choose by considering the frequency property of an image and a watermark. Also the amount of watermarking for watermark bit decide by considering the level of 2DDWT. This algorithm was implemented by C++ and experimented for invisibility and robustness with optical system. The experiment results showed that the method satisfied enough the invisibility of the inserted watermark and robustness against attacks. For the general attacks, the error rate of the extracted watermark was less than 15%, which is enough in robustness against the attacks.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.23 no.3
• /
• pp.291-298
• /
• 2019

In this paper, we propose a Fresnel transform method using various wavelet functions to efficiently decompose digital holograms. After implementing the proposed wavelet function-based Fresnelet transforms, we apply it to the digital hologram and analyze the energy characteristics of the coefficients. The implemented wavelet transform-based Fresnelet transform is well suited for reconstructing and processing holograms which are optically obtained or generated by computer-generated hologram technique. After analyzing the characteristics of the spline function, we discuss wavelet multiresolution analysis method based on it. Through this process, we proposed a transform tool that can effectively decompose fringe patterns generated by optical interference phenomena. We implement Fresnelet transform based on wavelet function with various decomposition properties and show the results of decomposing fringe pattern using it. The results show that the energy distribution of the coefficients is significantly different depending on whether the random phase is included or not.