KEYWORDS: Digital watermarking, Holography, Image restoration, Holograms, Image compression, Digital holography, Image quality, Binary data, 3D image reconstruction, Transform theory
We propose a new watermarking scheme that can be used to embed multiple bits and also resilient to JPEG compression and geometrical transforms such as scaling, rotation, and cropping, based on holographic watermark that allows multiple watermark recovery without original content (cover image). The holographic watermark is that Fourier transformed digital hologram, embedded into cover image in the spatial domain. The proposed method has not only increased robustness with a stronger embedding but also imperceptibility of the watermark in the evaluation process. To compare with the conventional scheme, the spread spectrum, we embedded and recovered maximum 1,024 bits that consist of binary number over PSNR (peak signal-to-noise ratio) 39dB. And also, we computed robustness with BER (bit-error rate) corresponding the above attacks.
We synthesized and analyzed the optical transfer function (OTF) of the modified triangular interferometer (MTI) using two-pupil synthesis method. In the case of MTI, we demonstrated that we can obtain bipolar functions and complex hologram without bias by two-pupil synthesis method.
KEYWORDS: Holograms, Digital watermarking, 3D image reconstruction, Digital holography, Information security, Image processing, Data hiding, Security technologies, Computer security, Fourier transforms
In this paper, we propose off-axis hologram watermarking technology, which could raise the robustness against the personal information's copy, falsification and alteration by making it possible to insert variable type's information and making strong privacy function. This technology should use security keys, hologram's depth information and the information in proportion to the depth information, at same time to extract inserted information and could insert huge information and insert owner or provider's own information with three-dimensional hologram watermark type to digital contents. So, this could have the high security. The proposed technology is strong at several images' processing and information's damage by the usages of hologram’s redundancy and this makes it hard to recognize inserted information visually. Especially, inserting much amount's information with various type is possible with its high privacy function by inserting information to several frequency's transform plane by using Fresnel transform differently with existing watermarking. So, we will show the substantial application's possibility and robustness of Fresnel hologram watermarking technology using like that characteristics through computer's imitation simulation.
KEYWORDS: Data hiding, Remote sensing, Received signal strength, Optical correlators, Joint transforms, Digital imaging, Signal detection, Feature extraction, Resistance, Image processing
In this paper, a new hybrid Opto-Digital multiple information hiding and real-time extracting system is suggested and implemented. The multiple information hiding system in which the multiple information can be hided in an arbitrary cover image is digitally implemented by using the random sequence and Hadamard matrix. In addition, a real-time optical extraction system in which the hidden information in a cover image can be extracted in real-time is implemented by using an optical NJTC. From good experimental results on the digital hiding and optical extraction of some English alphabet characters, it has been suggested, in this paper, that implementation of hybrid Opto-Digital multiple information hiding and real-time extraction system can be possible.
KEYWORDS: Data hiding, Digital imaging, Signal detection, Data communications, Electronics engineering, Optical engineering, Signal processing, Information security, Image compression, Image storage
During the past few years a variety of techniques have emerged to hide specific information within multimedia data for copyright protection, tamper-proofing and secret communication. The schemes for information hiding that have been proposed so far used either digital signal processing software or hardware. So they inevitably have a problem in some applications like automatic copyright control system, which need fast data-extracting scheme. In this paper, we show that the newly proposed optical correlator-based information hiding system has an advantage in that sense. In this scheme it is possible to simultaneously extract all the data hidden in one stego image and furthermore it is also possible to simultaneously extract all the data hidden in several stego images using optical correlators such as matched spatial filter and joint transform correlator.
We proposed a new spatio-angularly multiplexed holographic memory system using moving windows and double-focusing lens, which can eliminate crosstalk due to two neighboring moving windows in the vertical direction of the conventional moving window holographic memory system, and demonstrated its feasibility through optical experiments.
We proposed a new spatio-angularly multiplexed holographic memory system using moving windows and double-focusing lens, which can eliminate crosstalk due to two neighboring moving windows in the vertical direction of the conventional moving window holographic memory system, and demonstrated its feasibility through optical experiments.
General stereo vision system shows things in 3D, using two visions of left and right side. When the viewpoints of left/right sides are not in accord with each other, it give fatigue to human eyes and prevents them from having the 3-D feeling. Also, it would be difficult to track mobile objects that are not in the middle of a screen. Therefore, the object tracking function of stereo vision system is to control tracking objects to always be in the middle of a screen while controlling convergence angles of mobile objects in the input image of the left/right cameras. In this paper, object-tracker in stereo vision is presented which would track mobile objects by using block matching algorithm (Motion Estimation) of preprocessing and JTC.
For analysis of an effective phase code multiplexing in a holographic memory system, the Hadamard matrix (HAM) and the pseudorandom phase code (PRC) are generated and used as a reference beam. In computer simulations, the size of the address beam is fixed to 32 X 32 pixels, and 0%, 5%, 10%, 15%, 20%, or 25% phase error rate in a pixel is purposely added to the real phase values in order to consider the nonlinear phase modulation characteristics of the practical spatial-light modulator. Crosstalks and signal-to-noise ratios (SNRs) are comparatively analyzed for these two phase codes by calculating the auto- and cross-correlation. The cross-correlation mean values of the PRC and the HAM are 0.067 and 0.139, respectively, which means that the SNR of the PRC is higher than the HAM.
During the past few years a variety of techniques have emerged to hid specific information within multimedia data for copyright protection, tamper-proofing and secret communication. The schemes for information hiding that have been proposed so far used either digital signal processing software or hardware. So they inevitably have a problem in some applications like automatic copyright control system which need fast data-extracting scheme. In this paper, we show that the newly proposed optical correlator-based information hiding system has an advantage in that sense. In this scheme it is possible to simultaneously extract all the data hidden in one stego image and furthermore it is also possible to simultaneously extract all the data hidden in several stego images using optical correlators such as matched spatial filter and joint transform correlator.
By controlling the pixels of a liquid crystal display (LCD) electronically, we fabricated a real-time moving window on a LCD, through which light passes. Using the moving window and multi-focusing lens, we suggested a non-mechanical spatio- angular multiplexed holographic memory system and demonstrated its feasibility through optical experiments. The principle of the proposed method and optical experimental results are also presented.
In the typical stereo vision system, when the fixation points of the left and right images are mismatched or the moving object is not in the center of the screen, not only the observer is fatigued and unconscious of three-dimensional effect, but also hard to track the moving object. Therefore, stereo object tracking is necessary that controls the convergence angle, the angle between the optic axes of cameras and locates the moving object at the center of the screen. In this paper, we propose and demonstrate a stereo object tracking simulator based on the optical JTC.
A stereo vision system, as it receives two images equivalent to the one shown on left and right human eyes, can provide 3-D effect. However, the stereo disparity caused by the different parallax of the two images makes an observer feel fatigued and reduces the 3-D effect. Therefore, this paper presents a new approach to keep the stereo disparity to be zero via a JTC- based adaptive tracking of a moving object. In this method, the optical JTC system tracks the relative locations of a moving objects via measuring the correlation peak of the two images. Through some optical experiments the proposed stereo vision system is proved to be insensitive to background noises and control the convergence angle in real-time.
KEYWORDS: Holograms, 3D image reconstruction, Digital holography, Fourier transforms, 3D modeling, Digital imaging, 3D image processing, Data modeling, Fringe analysis, Reconstruction algorithms
This paper presents a ne method to calculate an image hologram pattern for a 3D object modeled as a stack of horizontally sliced 2D images. It is shown that the proposed method manipulates data on the angular spectrum domain, just as a recently presented method by Leseberg and thus it is regarded as an approximation to the Leseberg's method. Major differences arise in the implementation where it utilizes FFT in two perpendicular directions, which reduces the computational load considerably although additional interpolation process is required. We finally provide some comparisons between the proposed method and the existing methods in terms of computational complexities and performances.
We present a new holographic display system that reconstructs the complex hologram (which is free from the bias and the conjugate image) obtained from the modified triangular interferometer. This system is based on the Mach- Zehnder interferometer with modification of inserting liquid crystal displays (LCDs) and a wave plate. The information of the real and imaginary parts of the complex hologram are transferred to LCDs and the lights passed through LCDs are recombined by a beam splitter. By Fresnel diffraction, the desired image is reconstructed. We demonstrated through theoretical analysis and experiments that the image reconstruction from the complex hologram is possible using the proposed system.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.