Effect of gloss and diffuse reflectance of display frames on visual comfort

Abstract— A series of 12 display frames of different combinations of gloss levels and diffuse reflectance levels was mounted on a display to test the visual comfort of 31 test subjects. The frames were tested in a controlled environment where a light reflex was purposefully visible on the frame. The intensity of the light reflex was controllable by the user, and the dial setting was recorded for each frame. The frames were also shown in two different test office environments, one light and one dark. Qualitative comments about the frames were recorded. A gloss level of 30 gloss units corresponded to about 30% of test subjects that wanted no reflex at all to be visible on the frame. There was a significant effect of frame gloss on the acceptable light level of the reflex. When the acceptable‐light‐level dial setting was converted to luminance contrast, the acceptable luminance contrast on the frames decreased with increasing gloss, and this effect was more pronounced for black frames.     

Visual quality of high‐contrast projection screens. Part I: Visibility of screen‐based artifacts and noise

Abstract— The investigation of visual‐quality issues for high‐contrast projection screens such as those used for avionics projection displays and other applications requiring a high level of ambient light rejection will be described. Visibility of artifacts and noise generated by the optical and structural properties of a variety of high‐contrast projection screens was characterized by both empirical, subjective image quality evaluations and a suite of objective screen‐quality metrics. At least two of these metrics were found to provide very good correlation with the subjective assessment. These metrics are applicable to any display system where spatial‐noise artifacts are an issue, such as with direct‐view AMLCDs with anti‐glare treatments.     

Effects of discomfort glare on performance in attending peripheral visual information in displays

Large screens have become more popular in recent years. Because of the increasing size of displays, the amount of information presented in the peripheral visual field has gained importance in many tasks on visual display units. Users of displays are often exposed to some change or difference in luminance in or between different areas of a display, which in turn may produce a phenomenon known as discomfort glare. Discomfort glare is likely to affect cognitive performance. The performance in the visual periphery is more susceptible to disturbances as is the case for the performance in the central visual field.     

An affordable surround‐screen virtual reality display

Abstract— Building a projection‐based virtual reality display is a time‐, cost‐, and resource‐intensive enterprise, and many details contribute to the final display quality. This is especially true for surround‐ screen displays where most of them are one‐of‐a‐kind systems or custom‐made installations with specialized projectors, framing, and projection screens. In general, the costs of acquiring these types of systems have been in the hundreds and even millions of dollars, specifically for those supporting synchronized stereoscopic projection across multiple screens. Furthermore, the maintenance of such systems adds an additional recurrent cost, which makes them hard to afford for general introduction in a wider range of industry, academic, and research communities. A low‐cost easy‐to‐maintain surround‐screen design based on off‐the‐shelf affordable components for the projection screens, framing, and display systems is presented. The resulting system quality is comparableto significantly more expensive commercially available solutions. Additionally, users with average knowledge can implement this design, and it has the added advantage that single components can be individually upgraded based on necessity as well as available funds.     

Surface treatment,reflectance, and age effects on electronic‐paper reading performance

Abstract— This study is intended to explore the legibility and visual fatigue of different age users under various surface treatments and reflectance of electronic paper. Through the method of character‐search task, the results indicated that compared with single types of treatment [anti‐reflection (AR) 0.8%, anti‐glare, 43% haze), the compound treatment of anti‐reflection and anti‐glare (ARC) exhibited the same legibility, and it showed superior properties to effectively reduce visual fatigue. Hence, it is suggested that electronic‐paper manufacturers should choose the compound surface treatment for better visual performance. On the other hand, the findings also validated that enhancing the reflectance of electronic paper to the same level as regular paper (about 80%) is worthy to be practically implemented. Based on the results of this study, electronic‐paper manufacturers can take useful information to fulfill ergonomic requirements on product design.     

Eye symptoms and reading abilities of computer users subjected to visually impaired direct glare

Computer work is a visually demanding task associated with adverse eye symptoms. Frequent use of digital displays is known to cause a deterioration of the so-called binocular control. Direct glare further reduces the capacity for binocular coordination during computer work, leading to reduced reading ability and increased eye symptoms.The purpose of this study was to investigate the effect of different luminance levels of direct glare on binocular eye movement control and reading ability in a computer work environment.Sixteen participants with normal binocular vision performed equal reading tasks in a balanced study. Three controlled lighting conditions of direct glare (2000, 4000 and 6000 cd/m²) were tested, in addition to no glare. After each trial, the participants answered survey questionnaires regarding their understanding of the text, as well as their subjective experience of workload and perceived vision. Horizontal fixation disparity (FD) was measured before and after the reading tasks to evaluate binocular eye movement control.When comparing the responses of visual experience, a significant difference in reported eye symptoms was found between lighting conditions. Based on the variation (SD), a significant difference was found within mean values of repeated measurements of horizontal FD and a significantly higher variation in a comparison of initial FD values measured during lighting conditions of no glare, to final measured values in all three glare conditions. Reading ability was found to be significantly negative affected with the adversity of lighting conditions.This study supports the contention that binocular eye movement control is reduced caused by direct glare. Even lower degree of disability glare caused eye symptoms. The results establish the argument that working with flat screens raises visual demands.     

Visual experience of quality degradation when viewing computer and notebook displays from an oblique angle

Abstract— This study focused on evaluating the user experience of the viewing‐angle‐dependent quality of computer and notebook displays. The tests were performed in a test lab using a notebook with a prismatic display and a computer monitor with a conventional LCD. The notebook display was tilted and turned during an image‐quality test and tilted during an acuity test. On the computer monitor, the turn and tilt was simulated in the image‐quality test, for checking the TCO requirements. The results from the image‐quality test show that the parameter used in the TCO requirement, luminance ratio, would be a reasonable predictor of image quality. However, the experiment with the notebook display shows that, in general, this is not the case, especially for larger viewing angles where the physical characteristics do not show a gradual variation in luminance. Therefore, the luminance ratio in TCO requirements shall be used with caution. In addition, the results for the notebook display show that the visual acu ity decreased faster with increasing viewing angle than predicted from the luminance decrease alone. This means that it will be harder to resolve small details and will, therefore, have a negative influence on the visual ergonomics.     

A study on overhead glare in office lighting conditions

Abstract— High‐intensity light sources illuminating the human eye may create discomfort glare, or at higher intensities even disability glare. In many office lighting conditions, light from overhead luminaires in the ceiling may deliver stray light into human eyes, and as such create discomfort glare, generally referred to as overhead glare. In this paper, overhead glare for a LED luminaire comprising a matrix array of small LED sources using subjective evaluation methodologies and theoretical models, commonly accepted to evaluate glare, were investigated. The perceived overhead glare of the LED luminaire is evaluated at various luminance levels and at different angles (i.e., between 55 and 90°) with respect to the line of sight of the viewer. The results show that a luminaire comprising a matrix of high‐intensity point sources can cause overhead glare and can become glary at lower averaged luminance levels than a luminaire with a uniform light source even at high evaluation angles with respect to the line of sight of the viewer. In addition, the conventional UGR model for predicting discomfort glare needs adaptation for a reliable prediction of perceived overhead glare of complex LED luminaires consisting of a matrix of small‐sized high‐intensity light sources.     

New technique of obtaining visually perceived positions of 3-D images using movements of users’ bodies

Three-dimensional (3-D) images are perceived as images that float in front of the screens of 3-D displays. Users should be able to interact with these images instantaneously and accurately in applications where their bodies actually seen by them interact with the images. However, conventional techniques using just binocular disparity are too slow and inaccurate. Therefore, we propose a new technique where the visually perceived positions of images are obtained from the body movements of users. The feasibility of this technique was evaluated in an experiment using the positions obtained from users as they reached out to touch the images. These positions were closer to the visually perceived positions of the images than those calculated from binocular disparity. These findings demonstrate the feasibility of the proposed technique for 3-D interactive applications.     

Advanced automotive display measurements: Selected challenges and solutions

Today's trend in automotive displays is toward more, larger, better, and flexible panels. The requirements for cars differ largely from consumer displays: Automotive displays have unique requirements in terms of optical performance, longevity in harsh environment, and production of 100,000s per year per model. Consumer electronics displays, however, set the pace and premium automotive panels have to follow in short time because of customer expectations despite long development cycles. Advanced procedures and measurements have to be applied like lifetime and ambient light. In order to reduce the effort in specifying and evaluating car displays in terms of optical performance, the German Flat Panel Forum has set common requirements for automotive validation. As standard measurement procedures are often less suitable for automotive evaluation, dedicated methods were developed like Black Mura, gamma and visual assessment of anti‐glare surfaces. Standardization reduces the effort along the automotive display value chain. People in future autonomous cars will spend more time watching displays than today, which must then be of highest optical performance. Design visions trend to present information – and not displays – to driver and passengers, which includes seamless displays and smart surfaces. A simple integration of flat displays into dashboards is no longer state‐of‐the‐art.     

Reading dynamic Chinese text on the go

Abstract— Previous studies have shown that dynamic displays during rapid serial visual presentation (RSVP) privilege temporal rather that spatial information in overcoming the limits of small screens. Such studies have been conducted under stationary or idealized conditions using conventional desktop‐paradigm evaluation strategies, resulting in deficient understandings of how changes in motion affect users' ability to perform effectively. This study examined the impact of two important dynamic display factors on the reading comprehension achieved by participants while walking on a predefined path and standing: word‐by‐word and one‐line presentation formats and presentation rates of 182, 232, 282, and 332 characters per minute (cpm). The results of this study showed that an RSVP display can represent an alternative for reading textual information when a word‐by‐word format is presented with a 332‐cpm presentation rate. When the one‐line presentation format is used, however, a lower presentation rate of 282 cpm should be chosen. Future research should attempt to simulate real life more closely and explore the effects of the multiple functions performed by various RSVP displays on reading comfort and comprehension.     

Will musculoskeletal and visual stress change when Visual Display Unit (VDU) operators move from small offices to an ergonomically optimized office landscape?

This study investigated the effect of moving from small offices to a landscape environment for 19 Visual Display Unit (VDU) operators at Alcatel Denmark AS. The operators reported significantly improved lighting condition and glare situation. Further, visual discomfort was also significantly reduced on a Visual Analogue Scale (VAS). There was no significant correlation between lighting condition and visual discomfort neither in the small offices nor in the office landscape. However, visual discomfort correlated significantly with glare in small offices i.e. more glare is related to more visual discomfort. This correlation disappeared after the lighting system in the office landscape had been improved. There was also a significant correlation between glare and itching of the eyes as well as blurred vision in the small offices, i.e. more glare more visual symptoms. Experience of pain was found to reduce the subjective assessment of work capacity during VDU tasks. There was a significant correlation between visual discomfort and reduced work capacity in small offices and in the office landscape. When moving from the small offices to the office landscape, there was a significant reduction in headache as well as back pain. No significant changes in pain intensity in the neck, shoulder, forearm, and wrist/hand were observed.The pain levels in different body areas were significantly correlated with subjective assessment of reduced work capacity in small offices and in the office landscape.By careful design and construction of an office landscape with regard to lighting and visual conditions, transfer from small offices may be acceptable from a visual-ergonomic point of view.     

Visual effects of the luminance surrounding a computer display

The luminance surrounding a computer display can potentially reduce visibility of the display (disability glare), result in sensations of discomfort (discomfort glare) and result in transient adaptation effects from fixating back and forth between the two luminance levels. The study objective was to measure the effects of surround luminance levels upon these functions in younger and older adults to determine recommended surround luminance levels. The younger age group comprised 20 subjects (mean age 27.9 years, range 23 - 39) and the older group 17 subjects (mean age 55.5 years, range 47 - 63). The central task was presented with luminance of 91 cd/M(2), tested surround luminance levels were 1.4, 2.4, 8.9, 25.5, 50, 91, 175, 317, and 600 cd/M(2). Disability glare was tested with low contrast (20%) visual acuity charts, transient adaptation was tested with a task that required regular fixation between the two luminance levels, discomfort was measured with a questionnaire after reading stories with different surround luminance levels, and preferred luminance was measured by method of adjustment. The surround luminance significantly affected transient adaptation (p < 0.0001), optimal performance occurred at 50 cd/M(2) and above for the young group and at 91 cd/M(2) and above for the older group. Neither low contrast acuity (disability glare) nor symptoms when reading were significantly affected by surround luminance. There was wide variation in preferred surround luminance; however, average preferred surround luminance was 86.9 cd/M(2) for the young group and 62.2 cd/M(2) for the older group, slightly below the central luminance of 91 cd/M(2). The effects of the surround luminance within the tested range are not large; however, the data show that the lowest surround luminance levels should be avoided and that surround luminance levels at or slightly below that of the central task are preferred.     

Character‐contrast measurements on reflective displays using replica masks

Abstract— A replica‐mask method is presented to measure the contrast of character strokes on reflective displays. The method accounts for veiling glare introduced into the detector by the bright areas surrounding the dark characters. A sampling sphere is employed to provide a uniform diffuse surround. Measurements of the diffuse reflectances are provided with specular included and with specular excluded. For reflective displays, the contrast is the same as the ratio of the reflectances and does not scale with illuminance levels. Details are provided to replicate the measurement procedure.     

Subjective and objective evaluation of visual fatigue caused by continuous and discontinuous use of HMDs

During continuous use of displays, a short rest can relax users' eyes and relieve visual fatigue. As one of the most important devices of virtual reality, head‐mounted displays (HMDs) can create an immersive 3D virtual world. When users have a short rest during the using of HMDs, they will experience a transition from virtual world to real world. In order to investigate how this change affects users' eye condition, we designed a 2 × 2 experiment to explore the effects of short rest during continuous using of HMDs and compared the results with those of 2D displays. The Visual Fatigue Scale, critical flicker frequency, visual acuity, pupillary diameter, and accommodation response of 80 participants were measured to assess the subject's performance. The experimental results indicated that a short rest during the using of 2D displays could significantly reduce users' visual fatigue. However, the experimental results of using HMDs showed that short rest during continuous using of HMD induced more severe symptoms of subjectively visual discomfort, but reduced the objectively visual fatigue.     

Can a humanoid robot continue to draw attention in an office environment?

This study focuses on the use of humanoid robots in office environments, and investigates whether a robot can maintain the attention of passersby after initiation of face-to-face contact. Drawing attention can be considered as a first step in improving the continuity of use of robots; such continuity is one factor in validating their social acceptance, which must be considered when disseminating robots in offices. In this study, we assume that the robot approaches and greets users in order to make the users aware of its presence and encourage them to use it. In particular, the robots used in this study convey various greetings along with three nonverbal indicators (no motion, random motion, and face-to-face contact) when a passerby at the office is close to the robot. For a one-week period, we validated the social acceptance of the robot by examining how these robot motions influenced the rate and continuity of a passerby's attention. The results revealed that face-to-face contact can draw a high degree of attention, and that the presence of the robot affects the continuity with which attention is drawn. Finally, the paper discusses implications for future robot design, in terms of drawing and maintaining high rates of attention from users.     

Review Paper: The Helmholtz‐Kohlrausch effect

Abstract— The Helmholtz‐Kohlrausch (H‐K) effect is the influence of color purity on the perceived brightness of a color object (or source). In addition to a review of the effect, a survey of color and brightness‐perception studies from 1825 to the present (including our own studies on disabling glare) is presented. Disabling glare is the blinding experience which results from a bright source in our field of view. There has been a great deal of work on the H‐K effect, and this paper is our personal view of the subject. The H‐K effect has lead to new color‐appearance models which help to describe the brightness/luminance discrepancies, and we will only touch on this subject. It will be shown how the H‐K effect affects many of the displays, mobile devices, and phones. Additionally, how the H‐K effect is involved with our perception at mesopic light levels encountered during night driving will be discussed.     

Polarized task lighting to reduce reflective glare in open-plan office cubicles

This ergonomic study deals with the common situation where a glossy document is placed between a viewer and an under-shelf task light source in a common open-plan office cubicle workstation. With a task lamp in front, when looking at a document a viewer sees two images, the document itself and specular glare, which is the reflected image of the light source. Specular glare or veiling reflection causes eye discomfort, makes it difficult to read a document and has been thought to contribute to eyestrain. This paper analyzes the application of polarized lighting for this specific situation. The use of a linear polarized light source helps to minimize specular glare by darkening the reflected image of the light source on the document. The performance and predictive optimization of the use of polarized lighting in this situation is investigated according to female and male viewer height demographics. Theoretical predictions and light measurement analysis of specular glare reduction are compared with empirical results from testing on a panel of humans on semi-gloss finish and matte finish papers. This study shows that with the right alteration of a polarized light source position, specular glare may be significantly reduced, and correlations exist between the theory, empirical measurements and the human response to specular glare reduction.     

Adaptive Image‐Space Sampling for Gaze‐Contingent Real‐time Rendering

With ever‐increasing display resolution for wide field‐of‐view displays—such as head‐mounted displays or 8k projectors—shading has become the major computational cost in rasterization. To reduce computational effort, we propose an algorithm that only shades visible features of the image while cost‐effectively interpolating the remaining features without affecting perceived quality. In contrast to previous approaches we do not only simulate acuity falloff but also introduce a sampling scheme that incorporates multiple aspects of the human visual system: acuity, eye motion, contrast (stemming from geometry, material or lighting properties), and brightness adaptation. Our sampling scheme is incorporated into a deferred shading pipeline to shade the image's perceptually relevant fragments while a pull‐push algorithm interpolates the radiance for the rest of the image. Our approach does not impose any restrictions on the performed shading. We conduct a number of psycho‐visual experiments to validate scene‐ and task‐independence of our approach. The number of fragments that need to be shaded is reduced by 50 % to 80 %. Our algorithm scales favorably with increasing resolution and field‐of‐view, rendering it well‐suited for head‐mounted displays and wide‐field‐of‐view projection.     

Invited Paper: Depth reproducibility of multiview depth‐fused 3‐D display

Abstract— A multi‐view depth‐fused 3‐D (DFD) display that provides smooth motion parallax for wide viewing angles is proposed. A conventional DFD display consists of a stack of two transparent emitting screens. It can produce motion parallax for small changes in observation angle, but its viewing zone is rather narrow due to the split images it provides in inclined views. On the other hand, even though multi‐view 3‐D displays have a wide viewing angle, motion parallax in them is discrete, depending on the number of views they show. By applying a stacked structure to multi‐view 3‐D displays, a wide‐viewing‐angle 3‐D display with smooth motion parallax was fabricated. Experimental results confirmed the viewing‐zone connection of DFD displays while the calculated results show the feasibility of stacked multi‐view displays.