Showing papers by "Nagaaki Ohyama published in 1993"

Phase-added stereogram: calculation of hologram using computer graphics technique

Abstract: The wavefront reconstruction of hologram and holographic stereogram are analyzed to compare their imaging properties, and 'phase added stereogram' (PAS) is proposed as a technique for the calculation of computer generated hologram (CGH). Applying PAS, computer graphics techniques, for example, surface shading and hidden surface removal are easily applied in CGH generation process. The amount of computation is reduced compared with actual hologram calculation, and the quality of reconstructed image is superior to that of holographic stereogram. The theoretical expression of PAS is presented, and experimental results are also demonstrated.

Generation of intermediate parallax images for holographic stereograms

Abstract: We propose a new image processing approach to construct intermediate parallax-images from parallax-images at coarsely sampled viewpoints for Holographic Stereograms. Compared with the usual method that requires a large number of parallax-images, this approach reduces recording labor. In our approach, the intermediate parallax-images are made by projections of 3-D surface data, which are computed from several given parallax-images. It uses a new technique to reconstruct 3-D surface data of object scenes. The 3-D surface data is reconstructed from original parallax-images and camera positions. Almost all conventional techniques of stereo-matching need preprocess of feature extraction, and match only one stereo-pair at once. This technique simultaneously treats all given parallax images to find the depth map. In addition, feature extraction is not required in the matching process. Therefore it is possible to apply to almost all kind of scenes for holographic stereograms.

Image pickup system for reproducing image data using sensitivity function

Abstract: In a sensitivity function measuring unit, a CMD for picking up a beam from a light source is arranged through a photographic lens and a liquid crystal lens. A preamplifier, an A/D converter, a subtractor, a sensitivity function memory, a compressor, and R, G, and B sensitivity function memories are sequentially connected to the CMD through a switching circuit. An image reproducing unit for reproducing an original image using a sensitivity function calculated by the sensitivity function measuring unit is connected to a calculator for calculating a reproduced image, a frame memory for storing an image signal picked up by the CMD, and calculators for calculating sensitivity functions stored in the sensitivity function memories. The image reproducing unit is also connected to a display unit.

Estimation of surface shape from endoscopic image sequence

Abstract: In this paper, an approach is presented for 3-D surface shape estimation from monocular endoscopic images. The algorithms uses image sequence that are taken by shifting camera. In the first stage, the camera movements are estimated and the surface shape is roughly estimated by a method that is similar to stereo vision. In the second stage, the surface shape is refined by a multiview method. This multiview system selects several images from the image sequence and determines the corresponding view positions. Since each view contains noise, the algorithm solves for the depth distribution by minimizing an energy function such that all regions of several images are matched as close as possible in a least square sense while a smoothness constraint is applied on the solution. The contribution ratio of each view to the estimation is controlled by a weighting function that is decided depending on the geometric relationship between the surface point and each viewpoint. Principle of the method and experimental results are presented.© (1993) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Visualization of Three-Dimensional Data Using a Hybrid System

Abstract: The Fiber Optic Interferometric Sensors, FOIS, advent has opened the door to the field application of the interferometry. FOIS allow the disconession between a critical measurement stage (the interferometer) and the measurands site. Moreover, all the information about the measurands are coded in terms of optical phase modulation. Applications and recent advances of the Fiber Optic Interferometric Sensors technology will be reviewed. Laser-based FOIS and White-Light-based FOIS are the two main classes in which the FOIS are developed. Applications range from point sensors of physical parameters (vibration, acceleration, displacement, temperature, etc.) to chemical measurement (traces of ions in water) to sensing network for the development of smart structures FOIS participated to the foundation of the guided-wave single- mode technology and they are even today an important battle-field for experimenting advanced components and architectures.

ISAC Developments and Applications

Abstract: ISAC (Image Save And Carry) is an off-line system, where medical information including images can be easily interchanged among computer systems and modalities. Because ISAC system requires a full compatibility, a lot of efforts have been paid for standardization works. This paper reviews the developments of ISAC system and the security mechanism indispensable for medical applications. As an application of ISAC system in medicine, ISAC project in National Cancer Center will be also introduced.

Recording of high-quality 3D images by holoprinter

Abstract: Holographic (3-D) printer (holoprinter) is under development as a peripheral device for 3-D image processing systems For the automatic printing of distortion-free image, `multidot' recording method is developed In this paper, the technique for the synthesis of high-quality and gray-level images is presented, and the experimental results are demonstrated Also the method to record full-color image is introduced