The Experts below are selected from a list of 273 Experts worldwide ranked by ideXlab platform
D Ireland - One of the best experts on this subject based on the ideXlab platform.
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Single image random dot Stereogram: principles and clinical implications.
Journal of the American Optometric Association, 1996Co-Authors: D Y Lee, D IrelandAbstract:BACKGROUND The single image random dot Stereogram is different from traditional Stereograms in that it does not require a stereoscope or stereo glasses for viewing. There is an artistic variation of these Stereograms in which the random dots have been replaced with colorful geometric patterns. An observer needs to view them according to specific instructions. While most observers can see the hidden stereo images after a few trials, some are not able to perceive the effect even after numerous attempts. METHODS This paper explains the underlying principles by which these Stereograms are constructed and describes the reasons why some individuals are not able to appreciate this stereo effect. A unique requirement for the successful viewing of these Stereograms is divergence of the eyes from the plane of the Stereogram. This unusual divergence may be the reason for unsuccessful viewing. By converting a single image random dot Stereogram to a Brewster Stereogram, an observer can view the same Stereogram with a stereoscope, thus eliminating the divergence requirement. RESULTS Using this modified viewing method, some previously unsuccessful observers were able to see the stereo effect. CONCLUSIONS The main reason for unsuccessful viewing by a person with normal stereo vision is an inability to initiate or maintain the proper amount of divergence.
Osamu Watanabe - One of the best experts on this subject based on the ideXlab platform.
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Correlation Effect on Stereo Transparency
2015Co-Authors: Osamu WatanabeAbstract:Abstract—Stereo transparency is one of the important phenomena for the computational study of binocular stere-opsis, because this perception raises a fundamental issue of how binocular disparities are represented in the brain. We investigate the perceptual property of stereo transparency with a specific Stereogram generated by overlapping two ’identical ’ dot patterns in different depths. This Stereogram has potential matches leading to a unitary surface percep-tion as well as transparency perception, and which surface is perceived in this ambiguous Stereogram would reflect the property of the transparency detection mechanism in human stereopsis. The result suggests that the depth per-ception in this Stereogram is affected by the correlation be-tween overlapping patterns within a small area the size of which was approximately equal to the receptive field size in early visual cortex. 1
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Stereo transparency in ambiguous Stereograms generated by overlapping two identical dot patterns.
Journal of Vision, 2009Co-Authors: Osamu WatanabeAbstract:In binocular vision, observers can perceive transparent surfaces by fusing a Stereogram composed of two overlappingpatterns with different disparities. When dot patterns of two surfaces are identical, the Stereogram has potential matchesleading to both transparency and non-transparency (or unitary surface) perceptions. However, these two matchingcandidates are exclusive if the uniqueness assumption holds. This Stereogram can be regarded as a random-dot version ofthe double-nail illusion and a stereo version of the locally paired-dot stimulus that was used to investigate the neuralmechanism for motion transparency. Which surface is perceived in this ambiguous Stereogram would reflect the property ofthe transparency detection mechanism in human stereopsis. Here we perform a parametric study to examine the perceptualproperty in this ambiguous Stereogram. The result showed that the ability in transparency detection from this Stereogram isdetermined by the contrast reversal ratio between overlapping patterns within small regions the width of which was about0.4 deg. The width was similar to the receptive field sizes of neurons in striate cortex. The result suggests that the contrastreversal between two identical patterns would modulate activities of binocular neurons, and this modification gives a crucialeffect on the neural representation for overlapping disparities.Keywords: binocular stereopsis, stereo transparency, double-nail illusion, locally paired-dot stimulusCitation: Watanabe, O. (2009). Stereo transparency in ambiguous Stereograms generated by overlapping two identical dotpatterns. Journal of Vision, 9(12):24, 1
D Y Lee - One of the best experts on this subject based on the ideXlab platform.
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Single image random dot Stereogram: principles and clinical implications.
Journal of the American Optometric Association, 1996Co-Authors: D Y Lee, D IrelandAbstract:BACKGROUND The single image random dot Stereogram is different from traditional Stereograms in that it does not require a stereoscope or stereo glasses for viewing. There is an artistic variation of these Stereograms in which the random dots have been replaced with colorful geometric patterns. An observer needs to view them according to specific instructions. While most observers can see the hidden stereo images after a few trials, some are not able to perceive the effect even after numerous attempts. METHODS This paper explains the underlying principles by which these Stereograms are constructed and describes the reasons why some individuals are not able to appreciate this stereo effect. A unique requirement for the successful viewing of these Stereograms is divergence of the eyes from the plane of the Stereogram. This unusual divergence may be the reason for unsuccessful viewing. By converting a single image random dot Stereogram to a Brewster Stereogram, an observer can view the same Stereogram with a stereoscope, thus eliminating the divergence requirement. RESULTS Using this modified viewing method, some previously unsuccessful observers were able to see the stereo effect. CONCLUSIONS The main reason for unsuccessful viewing by a person with normal stereo vision is an inability to initiate or maintain the proper amount of divergence.
Hoonjong Kang - One of the best experts on this subject based on the ideXlab platform.
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numerical reconstruction of a full parallax holographic Stereogram with radial distortion
Optics Express, 2014Co-Authors: Jiyong Park, Elena Stoykova, Hoonjong Kang, Sunghee Hong, Youngmin Kim, Yong Suk Choi, Yongjung Kim, Soonchul Kwon, Seung-hyun LeeAbstract:Successful commercialization of holographic printers based on holographic Stereograms requires a tool for their numerical replaying and quality assessment before the time-consuming and expensive process of holographic recording. A holographic Stereogram encodes 2D images of a 3D scene that are incoherently captured from multiple perspectives and rearranged before recording. This study presents a simulator which builds a full parallax and full color white light viewable holographic Stereogram from the perspective images captured by a virtual recentering camera with its further numerical reconstruction for any viewer location. By tracking all steps from acquisition to recording, the simulator allows for analysis of radial distortions caused by the optical elements used at the recording stage. Numerical experiments conducted at increasing degree of pincushion distortion proved its insignificant influence on the reconstructed images in all practical cases by using a peak signal-to-noise ratio and the structural similarity as an image quality metrics.
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Numerical reconstruction of full parallax holographic Stereograms
3D Research, 2012Co-Authors: Jiyung Park, Elena Stoykova, Hoonjong Kang, Sunghee Hong, Seung-hyun Lee, Kwangmo JungAbstract:Holographic printers based on holographic Stereograms are constantly gaining popularity. A holographic Stereogram is recorded using 2D images of the 3D object or scene that are captured from multiple perspectives. Separation of capture and recording steps as well as checking of quality of the achieved 3D representation requires replaying of the composed holographic Stereogram by computer. This paper presents a simulator which, as a first step, builds a full parallax holographic Stereogram from the perspective images and, as a second step, reconstructs the hologram numerically for any viewer location by using a reconstruction algorithm proposed in the paper. To check the performance of the simulator we made a holographic Stereogram of a test 3D object from images acquired by a virtual re-centering camera which was translated along a virtual camera track and compared the result from the numerical reconstruction with the optical reconstruction from the printed holographic Stereogram of the same object. Open image in new window
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Accurate phase-added Stereogram to improve the coherent Stereogram.
Applied optics, 2008Co-Authors: Hoonjong Kang, Takeshi Yamaguchi, Hiroshi YoshikawaAbstract:We propose an “accurate” phase-added Stereogram, which can be defined as an improved phase-added Stereogram. Generally, the macroblock size transformed by the fast Fourier transform is the same as the segmentation size of the phase-added Stereogram. However, the proposed method uses a lager macroblock size than does the conventional method to reduce quantization error in discrete spatial frequencies in the spatial frequency domain. Therefore, even when the fast Fourier transform is used for calculation, the quality of the reconstructed image can be improved to be as clear as the Fresnel hologram.
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compensated phase added Stereogram for real time holographic display
Optical Engineering, 2007Co-Authors: Hoonjong Kang, Takeshi Yamaguchi, Tomohiko Fujii, Hiroshi YoshikawaAbstract:A common difficulty in displaying a Fresnel hologram in real time the required calculation of huge amounts of information. We propose a novel digital hologram generation method for real-time holographic display. It depends on compensation of the phase-added Stereogram, and can generate high-quality holograms rapidly. We describe a generation algorithm for the phase-added Stereogram, using the fast Fourier transform (FFT) for fast calculation, and the compensated phase-added Stereogram to get a reconstructed image as clear as the Fresnel hologram. Moreover, we present a method to define the optimum size of segmentation to get a clear reconstruction image and to achieve fast computation using the FFT. We have built a demonstration system to implement the proposed method. The system consists of a server, a client, and an optical holographic display system for real-time holographic display. The server generates 3-D information and transmits it on Ethernet. The client receives the information and generates a digital hologram using the compensated phase-added Stereogram. Finally, the generated hologram is displayed on the optical holographic display system in real time. We have achieved display of digital holograms at 15 frames/s with 1000 object points.
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Accurate Phase-Added Stereogram
Adaptive Optics: Analysis and Methods Computational Optical Sensing and Imaging Information Photonics Signal Recovery and Synthesis Topical Meetings o, 2007Co-Authors: Hoonjong Kang, Takeshi Yamaguchi, Hiroshi YoshikawaAbstract:In this paper, we propose “Accurate Phase-Added Stereogram” which is calculated by a similar way to the Phase-Added Stereogram, and its reconstructed image is as clear as the Fresnel hologram.
Pierre St. Hilaire - One of the best experts on this subject based on the ideXlab platform.
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Modulation transfer function of holographic Stereograms
International Conference on Applications of Optical Holography, 1995Co-Authors: Pierre St. HilaireAbstract:I calculate the modulation transfer function (MTF) characteristics of image-plane holographic Stereograms and describe how the MTF behaves with respect to factors such as image depth, resolution, and perspective window size. I then use this expression for the MTF to determine the optimum Stereogram parameters and compare the results of the analysis with those derived from a geometrical model.
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Modulation transfer function and optimum sampling of holographic Stereograms.
Applied Optics, 1994Co-Authors: Pierre St. HilaireAbstract:The modulation transfer function characteristics of image-plane holographic Stereograms are calculated, and the behavior of the modulation transfer function with respect to factors such as image depth, resolution, and perspective window size is described. The expression for the modulation transfer function is then used to determine the optimum Stereogram parameters, and it is shown how this approach can lead to significant computational economies in the display of three-dimensional data.
