High-resolution 3D display using time-division light ray quadruplexing technology.

We propose a flicker-reduced time-division light ray quadruplexing technology to improve both the spatial and angular resolutions of three-dimensional (3D) images. The proposed method uses an image-shift optical device with polarization gratings. By optimizing the design of the image-shift optical device and incorporating it into the display system, we confirmed that the resolution characteristics of 3D images displayed at a depth of 30 mm or more can be improved by up to 1.58 times. Furthermore, by developing the display system using a 120 Hz 8K projector with wobbling device and a wavelength-selective λ/2 plate for reducing flicker, we achieved high-resolution 3D image display with deeper depth.

Pixel-density and viewing-angle enhanced integral 3D display with parallel projection of multiple UHD elemental images.

This paper presents an integral three-dimensional (3D) display that efficiently enhances both the pixel densities and viewing angles of 3D images with parallel projection of elemental images. In the proposed method, ultra-high-definition (UHD) elemental images are projected and superimposed as parallel light rays from densely arranged compact UHD projectors onto a lens array. Three-dimensional images with enhanced pixel densities and viewing angles can be displayed by optimizing the projector positions and system design. The prototype yielded a horizontal pixel density of 63.5 ppi, approximately 97,000 pixels, and a viewing angle of approximately 30°, making it superior to previous integral 3D display systems.

Aktina Vision: Full-parallax three-dimensional display with 100 million light rays.

Natural three-dimensional (3D) images, perceived as real objects in front of the viewer, can be displayed by faithfully reproducing light ray information. However, 3D images with sufficient characteristics for practical use cannot be displayed using conventional technologies because highly accurate reproduction of numerous light rays is required. We propose a novel full-parallax light field 3D display method named 'Aktina Vision', which includes a special top-hat diffusing screen with a narrow diffusion angle and an optical system for reproducing high-density light rays. Our prototype system reproduces over 100,000,000 light rays at angle intervals of less than 1° and optimally diffuses light rays with the top-hat diffusing screen. Thus, for the first time, light field 3D image reproduction with a maximum spatial resolution of approximately 330,000 pixels, which is near standard-definition television resolution and three times that of conventional light field display using a lens array, is achieved.

Color moiré reduction and resolution enhancement of flat-panel integral three-dimensional display.

Color moiré occurs owing to the subpixel structure of the display panel in the integral three-dimensional (3D) display method, deteriorating the 3D-image quality. To address this, we propose a method for reducing the color moiré and improving the 3D-image resolution, simultaneously, by combining multiple 3D images. In the prototype system, triple 3D display units with lens arrays closely attached to 8K-resolution display panels are optically combined. By controlling the color moiré of the 3D image generated on each display and shifting and combining the elemental lenses constituting the lens array, sufficient reduction in the color moiré is realized, while suppressing the deterioration of the 3D-image quality, at a distant position from the lens array in the depth direction, along with an approximately two-fold enhancement of the resolution near the lens array.

Integral 3D display using multiple LCD panels and multi-image combining optical system.

We present a method to display an integral three-dimensional (3D) image without gaps between multiple display active areas by using multiple liquid crystal display (LCD) panels and multi-image combining optical systems (MICOS). We designed a MICOS to improve the resolution characteristics and decrease the luminance unevenness corresponding to the viewpoint. Furthermore, we developed a method for correcting the distortion of the integral 3D image by using image processing. We prototyped an integral 3D display using four 8K dual-green (8KDG) LCD panels and the improved MICOSs. The prototype display achieved to magnify the display area about 5.66 times more than when a single LCD panel was used.

Integral three-dimensional television with video system using pixel-offset method.

Integral three-dimensional (3D) television based on integral imaging requires huge amounts of information. Previously, we constructed an Integral 3D television using Super Hi-Vision (SHV) technology, with 7680 pixels horizontally and 4320 pixels vertically. We report on improved image quality through the development of video system with an equivalent of 8000 scan lines for use with Integral 3D television. We conducted experiments to evaluate the resolution of 3D images using an experimental setup and were able to show that by using the pixel-offset method we have eliminated aliasing produced by full-resolution SHV video equipment. We confirmed that the application of the pixel-offset method to integral 3D television is effective in increasing the resolution of reconstructed images.

Geometric analysis of spatial distortion in projection-type integral imaging.

In projection-type integral imaging, positional errors in elemental images and elemental lenses affect three-dimensional (3D) image quality. We analyzed the relationships between the geometric distortion in elemental images caused by a projection lens and the spatial distortion in the reconstructed 3D image. As a result, we clarified that 3D images that were reconstructed far from the lens array were largely affected, and that the reconstructed images were significantly distorted in the depth direction at the corners of the displayed images.

Depth-control method for integral imaging.

We present a method for controlling the depth of three-dimensional (3D) images reconstructed by integral photography. Incoherent light is reflected from 3D objects, propagates through a lens array, and is captured as the first elemental images by a capturing device. The second elemental images of the 3D images are generated by numerical processing from the first elemental images in accordance with the desired depth. The optical reconstruction of 3D images at the desired depth by the second elemental images is confirmed experimentally.

Wave optical analysis of integral method for three-dimensional images.

We analyze by wave optics an integral method that produces three-dimensional (3D) images. The point light source is given at the pickup stage, and the light wave passing through each elemental lens is obtained at the display stage. The amplitude distributions of the waves from each elemental image are the same around a specific point where a 3D image is formed. Since the light waves approaching the image plane from different elemental lenses are incoherent, the synthesized value is the sum of the squared amplitudes of the waves. Therefore the modulation transfer function of this integral method is given by that of a single elemental lens.

High-definition imaging system based on spatial light modulators with light-scattering mode.

We have developed a prototype high-definition imaging system using polymer-dispersed liquid-crystal (PDLC) light valves, which can modulate unpolarized light with high spatial resolution and exhibit a high optical efficiency, based on the light-scattering effect. We fabricated high-definition light valves with a fine polymer-matrix structure in a PDLC film by controlling the curing conditions used during the photopolymerization-induced phase separation and formation process. This device has excellent characteristics, such as a high resolution, with 50 lp/mm for a limiting resolution and greater than 20 lp/mm at the 50% modulation transfer function point, and a reflectivity of greater than 60%. An optically addressable full-color projection display was designed, consisting of three PDLC light valves, a schlieren optical system based on shift-decentralization optics with a xenon lamp illumination and input-image sources with 1.5 million pixels, including electrical image compensation of the gamma characteristics. We succeeded in displaying pictures on a 110-inch screen with a resolution of 810 TV lines and a luminous flux of 1900-2100 American National Standards Institute lumens.

High-definition real-time depth-mapping TV camera: HDTV Axi-Vision Camera.

We have developed a field-worthy, high-definition, real-time depth-mapping television camera called the HDTV Axi-Vision Camera. The camera can simultaneously capture both an ordinary HDTV color image and a depth image of objects on more than 1280 x 720 pixels at a frame rate of 29.97 Hz, or on 853 x 480 pixels at a frame rate of 59.94 Hz. The number of detectable pixels per unit time was increased by about 5 times that of the prototype camera by improving the sensitivity and resolution of the depthmapping camera. Short video clips demonstrate how depth information from the camera can be used to create a virtual image in actual television program production.

Gain-modulated Axi-Vision Camera (high speed high-accuracy depth-mapping camera).

We describe a novel real-time depth-mapping camera, the Gainmodulated Axi-Vision Camera, where pulsed laser light is combined with a gain-modulated camera. Depth resolution of 2.4 mm was obtained, which is higher than the resolution of the previously reported depth-mapping Axi- Vision Camera. Pixel-by-pixel depth information of 768 x 493 pixels is obtainable at one half of the video frame rate (15 Hz). A short movie clip is attached that illustrates the depth measurement operation. The merits of the Gain-modulated Axi-Vision Camera are high-resolution, real-time operation, and a relatively simple optical system. These merits primarily arise from the ultra-fast exposure time using a pulsed laser diode.