Characterization of crosstalk in stereoscopic display devices

Many different types of stereoscopic display devices are used for commercial and research applications. Stereoscopic displays offer the potential to improve performance in detection tasks for medical imaging diagnostic systems. Due to the variety of stereoscopic display technologies, it remains unclear how these compare with each other for detection and estimation tasks. Different stereo devices have different performance trade‐offs due to their display characteristics. Among them, crosstalk is known to affect observer perception of 3D content and might affect detection performance. We measured and report the detailed luminance output and crosstalk characteristics for three different types of stereoscopic display devices. We recorded the effect of other issues on recorded luminance profiles such as viewing angle, use of different eye wear, and screen location. Our results show that the crosstalk signature for viewing 3D content can vary considerably when using different types of 3D glasses for active stereo displays. We also show that significant differences are present in crosstalk signatures when varying the viewing angle from 0 degrees to 20 degrees for a stereo mirror 3D display device. Our detailed characterization can help emulate the effect of crosstalk in conducting computational observer image quality assessment evaluations that minimize costly and time‐consuming human reader studies.     

A crosstalk model and its application to stereoscopic and autostereoscopic displays

We propose a model to quantify the crosstalk phenomenon for stereoscopic and autostereoscopic displays, separate crosstalk contributed from co‐location image contrast (CIC) and system crosstalk (SCT), introduce gray scale dependency of CIC, modify model for gray scale dependency of SCT in active type 3D displays, and apply the model to derive the 3D luminance and SCT measurement formulas. The model might serve as a basis for the 3D metrology, and the results of this research should be of reference value to hardware makers and inspectors of stereoscopic and autostereoscopic displays.     

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。     

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.     

Visual comfort in 2D/3D modes of glasses‐type stereoscopic displays

In this study, we compared visual comfort in 2D/3D modes of the pattern retarder (PR) and shutter glasses (SG) stereoscopic displays by changing viewing factors and image contents. The viewing factors include ambient illuminance/monitor luminance/background luminance and image contents mainly are determined with different disparity limits. The degrees of 2D/3D visual comfort were investigated by using various combinations of ambient illuminance, monitor luminance, background luminance, and disparity limit. A series of psychological experiments were also performed to compare 2D and 3D viewing experiences for the passive PR and active SG stereoscopic displays and to discover more comfortable conditions under various variable combinations. The experiment results show that the various variable combinations affecting visual comfort in the passive PR and active SG stereoscopic displays were significantly different. Finally, we suggest more comfortable conditions of viewing 2D and 3D images for the PR and SG stereoscopic displays.     

Measurement of binocular disparity in polarized based stereoscopic display by using digital camera

This work presents an image displacement measurement by using a box pattern and the edge spread function analysis in the polarized based stereoscopic displays. The measurement determines to identify three factors (i.e., box size, image displacement, and spatial frequency response (SFR)) from the box patterns. The polarized based stereoscopic displays might sacrifice pixels for producing 3D images, which might produce errors in the image displacement and then affect the depth perception indirectly. Based on the measurement, the errors can be quantified by using the three factors. Owing to the light leakage distorting the edge spread function to obtain an inferior SFR, exactly how light leakage affects the edge spread function can be resolved on the basis of the SFR results, especially at a frequency (1/display pixel) of 1.9 in the case of the horizontal displacement. Light leakage also induces the error of the box height in even and odd intervals of the vertical displacements more than 2 pixels and 0.5 pixels, respectively. The image displacement measurement provides a simple and comprehensive means of evaluating the optical characteristics, disparity, and sharpness of the stereoscopic displays, via the three factors.     

Exploring crosstalk perception for stereoscopic 3D head‐up displays in a crosstalk simulator

In today's upper class vehicles, head‐up displays (HUDs) are state of the art human–machine interfaces used to increase driving security and comfort. Working with a stereoscopically perceived viewing impression, a novel automotive 3D HUD would allow the simultaneous visualization of multiple contents in various depth planes. However, stereoscopic crosstalk is one of the most important parameters influencing the image quality of stereoscopic systems. We present a setup to simulate crosstalk including a specific software solution. It constitutes a platform to explore the effects of stereoscopic crosstalk in the augmented reality viewing conditions of a 3D HUD. As the setup allows the variation of numerous parameters, it provides a versatile research platform. By means of it, we investigate the variation of the visibility and acceptability thresholds of crosstalk over various parameters. Our results include the finding that they decrease with rising contrast affirming this behavior known for conventional stereoscopic displays for stereoscopic see‐through displays.     

Method to suppress speckle noise using time multiplexing in phase‐only holographic display

In holographic display, the reconstructed image suffers from speckle noise severely. In this paper, we propose a method to suppress speckle noise using time multiplexing in phase‐only holographic display. Adjacent pixels of the recorded object are separated into object point groups firstly. Particularly, the pixel interval of each object point group is larger compared with the conventional pixel separation method. And then, sub‐computer–generated holograms (sub‐CGHs) are calculated by the modified Gerchberg–Saxton (GS) algorithm with different initial random phases. Finally, the final integrated image is reconstructed with low speckle noise using time multiplexing technique. Both numerical and optical experimental results are presented to demonstrate the effectiveness and feasibility with our proposed method.     

基于Java3D的立体显示技术及其在仿真中的应用

提出用虚拟环境建模API Java3D产生场景左右眼图像的关键技术,以及用Java3D如何控制影响立体显示效果的主要因素,这些主要因素是左右图像视差、虚拟眼睛视场宽度和虚拟眼睛到显示平面的距离。这些技术已成功应用于Java3D开发的汽车驾驶仿真系统中以实现立体显示。这些技术为用Java3D开发视景仿真系统和三维立体视觉游戏软件提供支持。     

Cross‐talk acceptability in natural still images for different (auto)stereoscopic display technologies

Abstract— One of the most annoying distortions in (auto)stereoscopic displays is probably cross‐talk, visible as double edges, which is mainly caused by an imperfect separation of left‐ and right‐eye images. For different types of three‐dimensional (3‐D) displays, cross‐talk is caused by different origins, which could result in different levels of perceived image distortion. To evaluate the influence of (auto)stereoscopic display technology on cross‐talk perception, optical measurements and subjective assessments were performed with three different types of 3‐D displays. It is shown with natural still images that the 3‐D display technology with the lowest luminance and contrast level tolerates the highest level of cross‐talk, while still maintaining an acceptable image‐quality level.     

A method for reproducing apparent continuous depth in a stereoscopic display using “Depth‐Fused 3D” technology

Abstract— A new method that can present fine depth increments in a stereoscopic display is proposed. In typical stereoscopic displays, depth can be presented by binocular disparity, but binocular disparity of less than one pixel cannot be displayed because, in general, electronic displays have discrete pixels. We combined binocular disparity and modulation of the edge luminance in DFD (depth‐fused 3D) displays. In an experiment, the perceived depth could be continuously changed by modulating the edge luminance only. Therefore, continuous depth can be produced by combining binocular disparity and modulation of edge luminance distribution.     

Effect of 3D depth on the resolution and the observed image for auto‐stereoscopic multi‐view 3D display

In auto‐stereoscopic multi‐views, blurring occurs due to the incomplete separation of views for non‐zero depths. How this blur affects a 3D image was investigated using the commercial multi‐view 3D. The 3D input signal consisted of the square pattern and the gratings of various width and gray level values of G1 and G2. The various combinations of G1 and G2 were used to investigate the dependence of blur on gray G1 and G2 values. The 3D depth caused blurring, which caused a decrease in contrast modulation. Hence, the 3D resolution determined from contrast modulation was affected by the depth and became worse with increasing depth. Therefore, 3D resolution may be used to define the depth range within which the image degradation due to blurring is acceptable. Blur edge width values at the boundaries of gray G1 and G2 were measured and found to be similar irrespective of G1 and G2 values at the same depth. This was because blur was caused by the incomplete separation of views that are independent of G1 and G2. Hence, the blurriness of the observed 3D image is determined only by the depth. The 3D resolution and blur edge width might be useful to characterize the performance of auto‐stereoscopic multi‐view 3D.     

Interaction and visual performance in stereoscopic displays: A review

In this paper, authors systematically selected and reviewed articles related to stereoscopic displays and their advances, with a special focus on perception, interaction, and corresponding challenges. The aim was to understand interaction‐related problems, provide possible explanations, and identify factors that limit their applications. Despite promising advancements, there are still issues that researchers in the field fail to explain precisely. The two major problems in stereoscopic viewing are, compared with the real world, objects are perceived to be smaller than they actually are and there are discomfort and visual syndromes. Furthermore, there is general agreement that humans underestimate their egocentric distance in a virtual environment (VE). Our analysis revealed that in the real world, distance estimation is about 94% accurate, but in VE, it is only about 80% accurate. This problem could reduce the efficacy of different sensory motor‐based applications where interaction is important. Experts from human factors, computing, psychology, and others have studied contributing factors such as types of perception/response method, quality of graphics, associated stereoscopic conditions, experience in virtual reality (VR), and distance signals. This paper discusses the factors requiring further investigation if the VR interaction is to be seamlessly realized. In addition, engineering research directions aiming at improving current interaction performances are recommended.     

Measurement of the lens accommodation in viewing stereoscopic displays

In observing the stereoscopic display at the viewing distance of 1 m, the amount of the perceived depth was determined by the positions of the crossing point that the viewing direction of two eyes intersect. The positions of the crossing points of stereoscopic stimuli were controlled, and the accommodation was measured by the autorefractometer for the seven participants. Accommodation was also measured when viewing the real film chart which was placed at the same position as these crossing points. The accommodation change when viewing the stereoscopic display was measured to be noticeable only when the crossing point was quite near the participant, but this change was still much smaller compared with the accommodation change when viewing the real film chart. This change in accommodation implies the possible occurrence of fatigue related to the accommodation–convergence conflict, while the constant accommodation within the range of DOF implies no conflict between the accommodation and convergence. This measurement scheme may be used to define the range of DOF where the accommodation remains little changed, and thus define the depth of the 3D object at which no accommodation–convergence conflict occurs, for a given stereoscopic display.     

Electro‐optical characteristics of a radio‐frequency plasma‐display module

Abstract— Plasma‐display modules intended for piled screens driven by a radio‐frequency voltage were investigated. The frequency range of a high‐efficiency RF discharge was determined. An efficiency of 4 lm/W at a brightness of 5000 cd/m² was obtained.     

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.     

Multi‐view 3‐D display employing a flat‐panel display with slanted pixel arrangement

Abstract— A flat‐panel display with a slanted subpixel arrangement has been developed for a multi‐view three‐dimensional (3‐D) display. A set of 3M × N subpixels (M × N subpixels for each R, G, and B color) corresponds to one of the cylindrical lenses, which constitutes a lenticular lens, to construct each 3‐D pixel of a multi‐view display that offers M × N views. Subpixels of the same color in each 3‐D pixel have different horizontal positions, and the R, G, and B subpixels are repeated in the horizontal direction. In addition, the ray‐emitting areas of the subpixels within a 3‐D pixel are continuous in the horizontal direction for each color. One of the vertical edges of each subpixel has the same horizontal position as the opposite vertical edge of another subpixel of the same color. Cross‐talk among viewing zones is theoretically zero. This structure is suitable for providing a large number of views. A liquid‐crystal panel having this slanted subpixel arrangement was fabricated to construct a mobile 3‐D display with 16 views and a 3‐D resolution of 256 × 192. A 3‐D pixel is comprised of 12 × 4 subpixels (M = 4 and N = 4). The screen size was 2.57 in.     

Input and display registration in a stereoscopic workstation

Several techniques are described to obtain spatial registration between three-dimensional input devices and a stereoscopic video display. A video monitor is viewed through a half-silvered mirror, with left and right eye views time-multiplexed through video interlace and viewed with electronic shutter glasses. A magnetic six-degree-of-freedom digitizer and an ordinary magnetostrictive graphics tablet were used as input devices.     

In‐field assessment of display resolution and noise: Performance evaluation of a commercial measurement system

Abstract— Two key metrics of image quality for high‐fidelity displays, including medical displays, are resolution and noise. Until now, these properties have been primarily measured in laboratory settings. For the first time, a system consisting of a CCD camera and analysis software has been made commercially available for measuring the resolution and noise of medical displays in a clinical setting. This study aimed at evaluating this new product in terms of accuracy and precision. In particular, the project involved the measurement of the modulation transfer function (MTF) and the signal‐to‐noise ratio (SNR) of two medical imaging displays, one cathode‐ray tube (CRT) display and one liquid‐crystal display (LCD) using this camera/software system. To assess the system's precision, measurements were made multiple times at the same setting. To check for accuracy, the results were compared with published values of the MTF and noise for the same displays. The performance of the system was also ascertained as a function of the focus setting of the camera. The results indicated that for the LCD, when the camera is focused within ±0.6 mm of the optimum focus setting, the MTF values lie within approximately 14% of the best focus MTF at the Nyquist frequency and 11% of the optimum overall sharpness (∫ MTF² df). Similar results were obtained in the horizontal and vertical directions. For the CRT, this focus produced vertical and horizontal MTF values at the Nyquist frequency within 15.2% and 61.2% of the optimum focus MTF, respectively. The figures in terms of overall sharpness were 3.0% and 0.7%. The results for the noise measurements showed a repeatability of 3% for the LCD and 13% for the CRT and a relative (but not absolute) magnitude of the noise between the two displays reflective of prior measurements. Overall, the measurement system yielded reasonably precise resolution and noise results for both display devices. The accuracy was traceable to published results only for the MTF and for relative level of display noise with differences in the absolute magnitude of noise between current and prior measurements attributed to variations in the non‐standard techniques applied for display noise measurements.     

Experimental determination of the range of binocular disparity for which stereoscopic fusion occurs at a viewing distance of 2.5 m for a stereoscopic TV

The threshold for binocular disparity for which a participant can observe a clear stereoscopic image on a 3D TV using Patterned Retarder technology and polarizing eyeglasses is determined for a viewing distance of 2.5 m. An optotype, the letter “m” with a line thickness of 1.08 mm in the upward or downward direction, was used as the stereoscopic stimulus. Under the measurement conditions of the increase and decrease of binocular disparity of the stereoscopic stimulus, the binocular disparity thresholds for 40 participants were measured for the horizontal direction. Most of the participants were in their twenties. The thresholds were measured to be slightly larger for the condition of increasing binocular disparity compared with the condition of decreasing binocular disparity. Personal differences were measured to be noticeable.