Showing papers by "Nagaaki Ohyama published in 1995"
12 Apr 1995
TL;DR: A prototype model of the holographic 3D printer (holoprinter) is presented and the experimental results are reported in this article, where several elementary holograms are exposed in parallel, resulting in the reduction of total printing time.
Abstract: A prototype model of the holographic 3D printer (holoprinter) is presented and the experimental results are reported. The holoprinter is developed for the purpose of a peripheral device to produce 3D image hard copies of computerized data. By the prototype, the practical problems such as the requirements for the vibration isolation and the time for printing, are investigated. Through the experiment, we demonstrated that 3D images of high diffraction- efficiency can be recorded without air-floated optical bench. In addition, a new optical system for high-speed printing is proposed. Using an array of lenslet, several elementary holograms are exposed in parallel, resulting in the reduction of total printing time.
24 citations
Patent•
19 Dec 1995
TL;DR: In this paper, the spectral distribution of illumination light at a spot where a subject is photographed is corrected by correcting the spectral distributions of reproduced environment light, based on the spectral information of a subject's image.
Abstract: PROBLEM TO BE SOLVED: To reduce information transmission quantity by correcting the spectral distribution of reproduced environment light, based on the spectral distribution of illumination light at a spot where a subject is photographed. SOLUTION: A spectral picture photographing means 10 photographs a subject picture as spectral information. A photographing light spectral detecting means 20 detects the spectral distribution of illumination light at a photographing spot. A processing means 30 calculates the spectral distribution in photographing the subject picture with the same illumination light as that of the reproduction spot, based on a reproduction environment light spectral detecting means 70, a reproduction environment spectrum and a spectroscopic reflection rate distribution. COPYRIGHT: (C)1997,JPO
15 citations
TL;DR: A visualization method is proposed for future electronic endoscopes which can display conventional color images with effective enhancement of bloody areas and a statistical classification method is applied to discriminate between human gastric spectra of normal and bloody tissues.
Abstract: We design spectral functions for endoscopic color filters by applying a statistical classification method to discriminate between human gastric spectra of normal and bloody tissues. Estimated RGB color images are generated from light intensities taken through the color discriminant filters. We propose a visualization method for future electronic endoscopes which can display conventional color images with effective enhancement of bloody areas.
4 citations
TL;DR: Clinical experimental results of the estimation of the object’s surface structure from an image sequence taken through a conventional CCD endoscope are reported.
Abstract: The object’s surface structure can be obtained from an image sequence taken through a conventional CCD endoscope. This paper reports clinical experimental results of the method. The accuracy of the estimation is studied and a method to estimate the reliability of the reconstructed shape is also described.
4 citations
TL;DR: In this article, a new method is proposed for reconstructing wavefront from discretely sampled interferogram data obtained by a digital lateral shearing interferometer, where the reconstruction error caused by the difference between the amount of shear and the sampling interval can be removed.
Abstract: A new method is proposed for reconstructing wavefront from discretely sampled interferogram data obtained by a digital lateral shearing interferometer. Assumptions applied in the conventional methods are not used and reconstruction error caused by the difference between the amount of shear and the sampling interval can be removed. System error and the influence of the discrete sampling, which limit accuracy of the tested results of the lateral shearing interferometer, are analyzed.
2 citations
08 May 1995
TL;DR: In this article, an observation system was modeled for each energy window, and Monte Carlo technique was applied for modeling photon transport in a water-filled cylinder, and generalized analytic reconstruction from discrete samples (GARDS) was applied to estimate the source distribution.
Abstract: Scattered radiation in radioisotope imaging is considered in an estimation of radioactivity distribution in order to improve the image quality. To utilize the scattered components in the estimation, an observation system was modeled for each energy window, and Monte Carlo technique was applied for modeling photon transport in a water-filled cylinder. The observation system was assumed to have 8 energy windows between 90 keV and 154 keV for photons emitted by 99mTc, and in order to clearly show the contribution of scattered components, it was also assumed to collect only one view projection data. In computer simulations, generalized analytic reconstruction from discrete samples (GARDS) was applied to estimate the source distribution, and the results show that when a large number of photons are collected, scattered components could improve the image quality.© (1995) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.
2 citations
TL;DR: A new method to measure surface topography using a monocular endoscope is proposed, determined by a photometric method, and the actual size of the object can be determined.
Abstract: We propose a new method to measure surface topography using a monocular endoscope. The surface structure is obtained up to a scale factor from an image sequence taken through a conventional CCD endoscope. The scale factor is determined by a photometric method, and the actual size of the object can be determined. The principle and experimental results are presented.
2 citations
TL;DR: In this paper, a new CGH (computer generated hologram) common path interferometer is proposed, which can be used for testing an aspherical mirror with large aperture, and a spatial filter is used to stop extraneous lights so that interferograms with good contrast can be obtained.
Abstract: A new CGH (computer generated hologram) common path interferometer, which can be used for testing an aspherical mirror with large aperture, is proposed. This interferometer does not have a circle of least confusion, and a spatial filter can be used effectively to stop extraneous lights so that interferograms with good contrast can be obtained. The phase shifting technique can be easily applied to the interferometer. The method of designing and making the CGH zone-plate is described.
1 citations
TL;DR: In this paper, a defocused wavefront is used to calculate the shear value of the lateral shearing interferometer with an error less than the sampling interval of the detector.
Abstract: We analyze the influence of error in the measurement of shear value, which is a major source of error in tested results by the lateral shearing interferometer. A novel method is proposed for accurately measuring the shear of this interferometer. By introducing a defocused wavefront and making use of the wavefront slope data of the defocus and the parameters of the interferometer, we can calculate the shear value precisely, with an error less than the sampling interval of the detector. An experiment was conducted to show the effectiveness of the method.
1 citations
TL;DR: The concept of integrated processing is applied to an image associative memory system, and the system is optically implemented for high-speed parallel processing incorporating it with the computer.
Abstract: We present the concept of integrated processing to combine intuitive processing of neural networks with logical processing of the conventional digital computer. We investigate a way to embody the concept in the neural network system by introducing external constraints in terms of external input. The effect of the external input is analyzed using the generalized projection method. The concept of integrated processing is applied to an image associative memory system, and the system is optically implemented for high-speed parallel processing incorporating it with the computer. The experimental result is presented to illustrate the effectiveness of the external input to control the output of the image associative memory.
28 Aug 1995
TL;DR: This paper presents a new image retrieval method suitable for a large-scale image filing system used in, for example, medicine, and introduces two concept spaces into the retrieval method: one of the user, and the other of the system.
Abstract: This paper presents a new image retrieval method suitable for a large-scale image filing system used in, for example, medicine. Keywords for image retieval may be more ambiguous than those for document retrieval, and the meaning of the keywords depends on each user. In order to overcome this problem, we introduce two concept spaces into the retrieval method: one of the user, and the other of the system. The mapping relation between the two concept spaces is then updated through the learning process, so that the retrieval system can be optimized for each user. An optical implementation of this system is also proposed to realize a fast retrieval.
TL;DR: This paper proposes an approach to estimate the location of current sources under the condition that sources of different positions have little or weak correlation, based on a well-known regularization method, the truncated SVD method.
Abstract: It is well known that an inverse problem of biomagnetic imaging is generally ill-posed. Recently several attempts using biocoherence have been reported, but the ill-condition is not considered in these previous methods. If the conventional reconstruction formula is under the ill-condition, the reconstruction problem is also ill-posed and the ill-posedness cannot be improved. In this paper, we propose an approach to estimate the location of current sources under the condition that sources of different positions have little or weak correlation. Our method is based on a well-known regularization method, the truncated SVD method. Compared with the conventional method, our technique allows accurate determination of the location of current sources because it improves the ill-posedness of the inverse problem. We carried out computer simulations using the half-space conducting model and confirmed the effectiveness of our method.