Design of autostereoscopic two‐view 3D that uses the spherical concave surface and the parallax barrier

Autostereoscopic display where circular concave display was used was investigated in case of the parallax barrier and two‐view 3D. Equation of the barrier pitch of the parallax barrier was derived that depended on the radius of the curved display. Trajectories of the rays coming from the curved display through the parallax barrier were calculated. Calculated distribution of ray trajectories for the autostereoscopic display using curved display showed trends similar to those for the flat display.     

Multi‐planar plenoptic displays

Multi‐planar plenoptic displays consist of multiple spatially varying light‐emitting and light‐modulating planes. In this work, we introduce a framework to display light field data on this new type of display device. First, we present a mathematical notation that describes each of the layers in terms of the corresponding light transport operators. Next, we explain an algorithm that renders a light field with depth into a given multi‐planar plenoptic display and analyze the approximation error. We show two different physical prototypes that we have designed and built: The first design uses a dynamic parallax barrier and a number of bi‐state (translucent/opaque) screens. The second design uses a beam splitter to co‐locate two pairs of parallax barriers and static image projection screens. We evaluate both designs on a number of different 3D scenes. Finally, we present simulated and real results for different display configurations.     

A study of optimal viewing distance in a parallax barrier 3D display

The optimal viewing distance was proposed as a parameter for designing a parallax barrier 3D display. It can be designed based on simple geometric method and by considering the pitches of image display pixels and parallax barrier, or even including the aperture ratios of the image display pixels and parallax barrier. It can be analyzed by using ray tracing method. By considering the optical refraction index of the cover glass, the angular behavior of the system becomes more realistic; however, the geometric method is difficult to be used. We propose a revised method for estimating the view distance and angular behavior. In this paper, we have demonstrated a designated eye position (DEP) for each view and shown that multiple DEPs make a circular curve around the center of the display. We prove the new concept by comparing the optical ray tracing calculations and optical measurement.     

Characterizing image quality of autostereoscopic displays by using the maximum luminance at each viewing position

A metric of the 3D image quality of autostereoscopic displays based on optical measurements is proposed. This metric uses each view's luminance contrast, which is defined as the ratio of maximum luminance at each viewing position to total luminance at that position. Conventional metrics of the autostereoscopic display based on crosstalk, which uses “wanted” and “unwanted” lights. However, in case of the multiple‐views‐type autostereoscopic displays, it is difficult to distinguish exactly which lights are wanted lights and which are unwanted lights. This paper assumes that the wanted light has a maximum luminance at the good stereoscopic viewing position, and the unwanted light also has a maximum luminance at the worst pseudo‐stereoscopic viewing position. By using the maximum luminance that is indexed by view number of the autostereoscopic display, the proposed method enables characterizing stereoscopic viewing conditions without using wanted/unwanted light. A 3D image quality metric called “stereo luminance contrast,” the average of both eyes' contrast, is proposed. The effectiveness of the proposed metric is confirmed by the results of optical measurement analyses of different types of autostereoscopic displays, such as the two‐view, scan‐backlight, multi‐view, and integral.     

GPU Accelerated Direct Volume Rendering on an Interactive Light Field Display

We present a GPU accelerated volume ray casting system interactively driving a multi‐user light field display. The display, driven by a single programmable GPU, is based on a specially arranged array of projectors and a holographic screen and provides full horizontal parallax. The characteristics of the display are exploited to develop a specialized volume rendering technique able to provide multiple freely moving naked‐eye viewers the illusion of seeing and manipulating virtual volumetric objects floating in the display workspace. In our approach, a GPU ray‐caster follows rays generated by a multiple‐center‐of‐projection technique while sampling pre‐filtered versions of the dataset at resolutions that match the varying spatial accuracy of the display. The method achieves interactive performance and provides rapid visual understanding of complex volumetric data sets even when using depth oblivious compositing techniques.     

Simple method of characterizing the spatial luminance distribution at the user position for autostereoscopic 3‐D display

Abstract— The image quality of autostereoscopic 3‐D displays strongly depends on the user position. So, characterization of the spatial luminance distribution at the user position is important. For the measurement of the spatial luminance distribution, a method that places a diffuser screen at the user position and is illuminated by a 3‐D display has been investigated. By placing the diffuser screen and 3‐D display non‐parallel, the luminance distribution at the various distances can be determined. Though the accuracy of this measurement method is somewhat limited, the measuring procedure is fast and simple, compared with other time‐consuming methods.     

A toroidal‐lens designed structure for static type table‐top floating image system with horizontal parallax function

A new structure of horizontal parallax table‐top floating image system with toroidal‐lens optical film was developed. In this design, the circular arranged pico‐projectors limit the angular resolution of this system and display the floating image for surrounding viewing zones. In addition, the pinhole array and toroidal‐lens layer compose the optical film in the system and correspond with each other; both of them could be considered as a repeatable unit to control the spatial resolution of image. After passing through the optical film, the direction, position, shape, and divergence angle of light field could be controlled as fan ray, which has a widely scattered angle in latitude and high directivity in longitude direction. Moreover, to confirm the optical properties, the proposed structure was built in the commercially optical software, LightTools v8.3, which is widely used in the simulation of light distribution. Based on the imaging principle and the inverse light tracking method, displaying floating image with circular viewing zones would be achieved.     

A wide view auto‐stereoscopic 3D display with an eye‐tracking system for enhanced horizontal viewing position and viewing distance

This paper describes the development of auto‐stereoscopic three‐dimensional (3D) display with an eye‐tracking system for not only the X‐axis (right–left) and Y‐axis (up–down) plane directions but also the Z‐axis (forward–backward) direction. In the past, the eye‐tracking 3D system for the XY‐axes plane directions that we had developed had a narrow 3D viewing space in the Z‐axis direction because of occurrence of 3D crosstalk variation on screen. The 3D crosstalk variation on screen was occurred when the viewer's eye position moved back and forth along the Z‐axis direction. The reason was that the liquid crystal (LC) barrier pitch was fixed and the LC barrier was able to control the only barrier aperture position. To solve this problem, we developed the LC barrier that is able to control the barrier pitch as well as the barrier aperture position in real time, corresponding to the viewer's eye position. As a result, the 3D viewing space has achieved to expand up to 320–1016 mm from the display surface in the Z‐axis direction and within a range of ±267 mm in the X‐axis direction. In terms of the Y‐axis direction, the viewing space is not necessary to be considered, because of a stripe‐shaped parallax barrier.     

Circular camera array system for 3‐D displays based on the reconstruction of parallax rays

Abstract— A circular camera system employing an image‐based rendering technique that captures light‐ray data needed for reconstructing three‐dimensional (3‐D) images by using reconstruction of parallax rays from multiple images captured from multiple viewpoints around a real object in order to display a 3‐D image of a real object that can be observed from multiple surrounding viewing points on a 3‐D display is proposed. An interpolation algorithm that is effective in reducing the number of component cameras in the system is also proposed. The interpolation and experimental results which were performed on our previously proposed 3‐D display system based on the reconstruction of parallax rays will be described. When the radius of the proposed circular camera array was 1100 mm, the central angle of the camera array was 40°, and the radius of a real 3‐D object was between 60 and 100 mm, the proposed camera system, consisting of 14 cameras, could obtain sufficient 3‐D light‐ray data to reconstruct 3‐D images on the 3‐D display.     

Dual layered display that presents auto‐stereoscopic 3D images to multiple viewers in arbitrary positions

Dual layered display or also called tensor display that consists of two panels in a stack can present full‐parallax 3D images with high resolution and continuous motion parallax by reconstructing corresponding light ray field within a viewing angle. The depth range where the 3D images can be displayed with reasonable resolution, however, is limited around the panel stack. In this paper, we propose a dual layered display that can present stereoscopic images to multiple viewers located at arbitrary positions in observer space with high resolution and large depth range. Combined with the viewer tracking system, the proposed method provides a practical way to realize high‐resolution large‐depth auto‐stereoscopic 3D display for multiple observers without restriction on the observer position and the head orientation.     

Two‐parallax‐barriers‐based autostereoscopic liquid‐crystal display without cross‐talk

Abstract— An autostereoscopic liquid‐crystal display (LCD) consists of two parallax barriers and an LCD including a liquid‐crystal panel, and a backlight panel is proposed. Parallax barrier 1 is located between the backlight panel and the liquid‐crystal panel, and Parallax barrier 2 is located between the liquid‐crystal panel and viewers. The operation principle of the autostereoscopic display and the calculation equations for the parallax barriers are described in detail. The autostereoscopic LCD was developed and produces high‐quality stereoscopic images without cross‐talk at the optimal viewing distance and less cross‐talk than a conventional one based on one parallax barrier at other viewing distances.     

Curved OLED display to effectively enhance natural3D

We studied the stereoscopic effect obtained from a two‐dimensional image without using binocular parallax, which we call “natural3D” (n3D). Unlike a parallax‐based three‐dimensional (3D) display system, n3D causes less tiredness and is free from a decrease of the resolution by half because of image division and viewing position dependence. To make the display with these effects comfortable to use, we conducted statistical tests with sensory evaluation experiments and a quantitative evaluation based on physiological responses. These examinations revealed that the n3D effect can be effectively obtained by using, for example, the characteristics of an organic light‐emitting diode display, such as high contrast and easy bendability. This study discusses optimal display curvatures for displays of different sizes that enhance n3D and reduce tiredness, which are revealed through statistical tests. In addition, we performed an experiment with a frame called an n3D window (n3Dw) that is placed before the display such that a subject views the display through the opening of the frame. We found that the combination of a curve and the n3Dw causes n3D more effectively.     

三维立体显示综述

按基本工作原理是否为双目视差将三维立体显示分为两大类。基于双目视差原理的三维立体显示主要有眼镜/头盔式立体显示和光栅式自由立体显示,这类三维立体显示的技术相对成熟并有相应产品;非基于双目视差原理的三维立体显示主要有全息立体显示、集成成像立体显示和体显示等,这类三维立体显示的技术较不成熟,大多没有相应产品。对这些三维立体显示的器件结构、工作原理以及各自的特性进行了阐述。     

Electro‐optical transfer function preferences for LCD TVs: The effect of display brightness and surround illumination on preferred gamma

Abstract— Recent commercial liquid‐crystal‐display (LCD) televisions are larger and brighter than traditional televisions, thus impacting the viewing conditions in which they are viewed. These changes in viewing conditions may require different electro‐optical transfer functions (EOTFs) for LCD TVs than those for conventional TVs. Here, the way various EOTFs affect the preferred image quality of test images with changes in brightness and surround illumination conditions are examined. The first method used a gain, offset, and gamma (GOG) function with a range of gamma values, and the second method altered the intrinsic EOTFs. Image preference for the simulated EOTFs was determined using a paired‐comparison experiment for ten images. The first experiment took place in a darkened room at two display luminance levels. The results indicated that a gamma of 1.6 was most preferred overall although more so at a lower screen luminance level. In a second experiment, the procedure was repeated with a dim surround of 10% of the display's white point. With this surround, preference for a gamma value of around 1.6 at both screen luminance levels was more enhanced. These results indicated that image preference for different EOTFs is dependent on display luminance and that this dependence is maintained with a dim surround.     

Psychophysical evaluations of a current multi‐view 3‐D display: Its advantages in glossiness reproduction

Abstract— Although two‐view 3‐D displays requiring stereo glasses are on the market, the shape of objects they present is distorted when the observer's head moves. This problem can be solved by using a (passive) multi‐view 3‐D display because such a display can produce motion parallax. Another problem has to do with the surface quality of the presented object, but little is known about the fidelity of such displays as far as the surface quality goes. Previously, it was found that a two‐view 3‐D display has a problem in which glossiness deteriorates when the observer's head moves and that it can be alleviated by using a head tracker, whose data enables the display to produce correct motion parallax and luminance changes when the viewer's head moves. Here, it was determined whether this problem can be solved by using commercially available multi‐view 3‐D displays, whose finite number of viewpoints and certain amount of cross‐talk, however, make luminance changes inexact and smaller than they should be. It was found that this display can solve the problem to a certain extent.     

Image correction based on homography in stereoscopic projection display

Abstract— Stereoscopic and autostereoscopic projection‐display systems use projector arrays to present stereoscopic images, and each projector casts one parallax image of a stereoscopic scene. Because of the position shift of the projectors, the parallax images have geometric deformation, which influences the quality of the displayed stereoscopic images. In order to solve this problem, a method based on homography is proposed. The parallax images are pre‐transformed before they are projected, and then the stereoscopic images without geometric distortion can be obtained. An autostereoscopic projection‐display system is developed to present the images with and without calibration. Experimental results show that this method works effectively.     

Qualified viewing space determination of near‐eye and head‐up displays

A method for determining the extents of a qualified viewing space (QVS) based on repeatable and reproducible luminance measurements of augmented and virtual reality near‐eye displays is described. This QVS mapping can also use other display performance metrics such as (1) Michelson contrast, (2) modulation transfer function, or (3) color as boundary condition parameters. We describe the use of a 4‐mm‐diameter entrance pupil, 1° to 2° field of view tele‐spectroradiometer, to determine the luminance and color uniformity of the virtual image. A 1‐mm‐diameter entrance pupil is used to map the QVS boundaries based on luminance at the center of the virtual image. The luminance measurement results from a pair of binocular augmented reality display glasses in three separate eye relief planes of the QVS of both eyes are presented. The data are further reduced to provide a perimeter profile of the QVS for the 50% of peak luminance boundary points in each eye relief plane.     

Advances in the Dynallax solid-state dynamic parallax barrier autostereoscopic visualization display system

A solid-state dynamic parallax barrier autostereoscopic display mitigates some of the restrictions present in static barrier systems, such as fixed view-distance range, slow response to head movements, and fixed stereo operating mode. By dynamically varying barrier parameters in real time, viewers may move closer to the display and move faster laterally than with a static barrier system, and the display can switch between 3D and 2D modes by disabling the barrier on a per-pixel basis. Moreover, Dynallax can output four independent eye channels when two viewers are present, and both head-tracked viewers receive an independent pair of left-eye and right-eye perspective views based on their position in 3D space. The display device is constructed by using a dual-stacked LCD monitor where a dynamic barrier is rendered on the front display and a modulated virtual environment composed of two or four channels is rendered on the rear display. Dynallax was recently demonstrated in a small-scale head-tracked prototype system. This paper summarizes the concepts presented earlier, extends the discussion of various topics, and presents recent improvements to the system.     

The effect of stereoscopic viewing in a word‐search task with a layered background

Abstract— The benefits of stereoscopic viewing were explored in searching in words superimposed over a background. In the first experiment, eight participants searched for text in a normal 2‐D display, a 3‐D display using a parallax barrier, and a darkened 2‐D display of equivalent brightness to the 3‐D display. Word‐search performance was significantly faster for the bright 2‐D display vs. the 3‐D display, but when brightness was controlled, performance on the 3‐D display was better relative to the 2‐D (dim) display. In a second experiment, the effect of floating text vs. sinking background disparity was assessed across four background conditions. Twenty participants saw only the floating‐text (FT) condition and 20 participants saw only the sinking‐background (SB) condition. Performance of the SB group was significantly better than that of FT group, and the advantage of SB disparity was greater with the more‐complex backgrounds. Thus, when a parallax‐barrier 3‐D display is used to view text or other figural information overlaid on a background, it is proposed that the layer of primary interest (foreground) should be displayed with zero disparity (on the physical display surface) with the secondary layer (background) appearing to be sunk beneath that surface.     

Color reproduction with a various number of sub‐pixels

Monochrome reflective‐type displays are widely used for portable reading applications such as electric papers because this type does not need a back light unit and can be used outdoors for a long time. Color reflective‐type displays without back light units are desired to expand the market further. The current color reproduction is based on three sub‐pixel red, green and blue (RGB) methods, and when used in reflective type, its luminance is reduced to a third of that of monochrome type. Adding a white sub‐pixel to the current method can improve the luminance, making the sub‐pixel number four. However, in the case of a high resolution display with a four‐sub‐pixel method, the pixel structure is complex, and the luminance improvement may be limited. Instead of increasing the sub‐pixel number, two sub‐pixel methods are investigated. These methods can improve luminance with limited color gamut. The performances are compared with those of other methods quantitatively.