Effects of curved computer displays on visual performance,visual fatigue,and emotional image quality

This study investigated the effects of the curvature of curved computer displays on the visual performance, fatigue, and emotional image quality experienced by users during the performance of visual tasks. The characteristics of curved displays were compared and analyzed for different curvatures to investigate whether the curved displays showed improvements in terms of convenience of use when compared with flat displays. The visual performance results for the evaluated displays can be classified into three groups according to their response times, as (2000R = 2500R) > (3000R) > (3800R = 4500R = Flat). The visual fatigue results for average pupil size during a search task was 3.468 mm for flat and 3.355 mm for 2000R. This means that a 2000R curved display was found to be easier to use and thus generated less visual fatigue than a flat display when performing the same visual search task. Further, the results indicated that visual performance improved and visual fatigue decreased significantly as curvature increased. In this study, a curvature limit of 1700R was derived, when considering the image distortion of a 34‐in 21:9 curved display, and there was found to be no difference in the emotional image quality at curvatures greater than 2000R.     

Lighting characteristics, legibility and visual comfort of displays

In future, as well as visual human-computer interfaces, acoustic interfaces will get more and more important. However, the visual channel will be the more important channel due to its capacity. Therefore, it is necessary not only to optimize the display with regard to performance and time, but also to acceptance and subjective workload. On the one hand the single character (luminance, geometry, shape, colour) and on the other hand the arrangement of characters (distance of characters, image distortions, structure of text) should be adapted to human psychophysiological abilities. Moreover, the influence of the environment (lighting) and time-dependent phenomena (flicker, jitter) should be taken into consideration. Good ergonomics should imply the use of all possibilities which the flexible new technology offers for workplaces, including sensory or muscularly handicapped people.     

Lighting characteristics,legibility and visual comfort of displays

Abstract

In future, as well as visual human-computer interfaces, acoustic interfaces will get more and more important. However, the visual channel will be the more important channel due to its capacity. Therefore, it is necessary not only to optimize the display with regard to performance and time, but also to acceptance and subjective workload. On the one hand the single character (luminance, geometry, shape, colour) and on the other hand the arrangement of characters (distance of characters, image distortions, structure of text) should be adapted to human psychophysiological abilities. Moreover, the influence of the environment (lighting) and time-dependent phenomena (flicker, jitter) should be taken into consideration. Good ergonomics should imply the use of all possibilities which the flexible new technology offers for workplaces, including sensory or muscularly handicapped people.     

Effects of ambient illuminance on users' visual performance using various electronic displays

Abstract— This study investigated the effect of ambient illuminance (50, 500, 1500, 3000, 6000, and 9000 lx) on participants' visual performance using four electronic displays (conventional LCD under transmissive mode, conventional LCD under reflective mode, Ch‐LC display, and E‐ink display). Analysis results indicate that participants' visual performance shows significant difference under various ambient illuminance and electronic displays. The interaction between ambient illuminance and electronic display also has significant effect on participants' visual performance. When participants use the conventional LCD under transmissive mode, ambient luminance has no significant effect on participants' visual performance. However, participants' visual performance is significantly different under various ambient illuminances using the conventional LCD under reflective mode, Ch‐LC display, and E‐ink display. The conventional LCD under transmissive mode is the only choice at a lower illuminance of 50 lx. Higher illuminance (500 lx) for E‐ink displays may result in as good a performance as the conventional LCD under transmissive mode; nevertheless, much higher illuminance (1500 lx) for the conventional LCD under reflectance mode and Ch‐LC display may achieve better performance.     

Effects of ambient illuminance and electronic displays on users' visual performance for young and elderly users

Abstract— This study investigated the effects of age (young participants aged 20–30 and elderly participants older than 60), ambient illuminance (50, 500, 1 500, 3000, 6000, and 9000 lx) on participants' visual performance when using various electronic displays (conventional transmissive LCD, Ch‐LC display, and E‐ink display). Overall, the results indicated that participants' visual performance showed sign if icant difference among various ambient il luminance cond itions, electronic displays, and between two groups of participants. Significantly different visual performance was observed between young and elderly participants. The interaction among ambient illuminance, type of electronic display, and age had a significant effect on participants' visual performance. When participants used the E‐ink display, both young and elderly participants had significantly worse visual performance under an ambient illuminance of 50 lx compared to other illuminance settings. When participants used the Ch‐LC display, young participants had significantly worse visual performance under an ambient illuminance of 50 lx compared to other illuminance settings, but elderly participants had significantly better visual performance under an ambient illuminance higher than 1500 lx. When young participants used a conventional transmissive LCD, the ambient illuminance had no significant effect on their visual performance. When elderly participants use a conventional transmissive LCD, an illuminance of 50 and 6000 lx seem to have a detrimental effect on their visual performance.     

Measuring visual fatigue and visual discomfort associated with 3‐D displays

Abstract— This research identifies methods for signs of visual complaints associated with stereoscopic displays. Two potential causes for contradictory results concerning these signs in previous research are hypothesized: (1) not all clinical tests are equally appropriate and (2) there is a natural variation in susceptibility amongst people with normal vision. An optometric screening differentiated participants with moderate binocular status (MBS) from those with good binocular status (GBS). In a 2 × 2 within‐subjects design (2‐D vs. 3‐D and MBS vs. GBS), a questionnaire and eight optometric tests (i.e., binocular acuity, aligning prism, fixation disparity, heterophoria, convergent and divergent fusional reserves, vergence facility, and accommodation response) were each administered before and immediately after a reading task. Results revealed that only participants with MBS in 3‐D conditions showed clinically meaningful changes in fusion range, experienced more visual discomfort, and performed worse on the reading task. Acombination of fusion range measurements and self‐report is appropriate for evaluating visual complaints of stereoscopic stills, and people with a MBS are more susceptible to visual complaints associated with stereoscopic displays. A simple measurement tool, i.e., the ratio of reading performance between 2‐D and 3‐D, to categorize people based on their binocular status is proposed.     

Preferred viewing distance and screen angle of electronic paper displays

This study explored the viewing distance and screen angle for electronic paper (E-Paper) displays under various light sources, ambient illuminations, and character sizes. Data analysis showed that the mean viewing distance and screen angle were 495 mm and 123.7 degrees. The mean viewing distances for Kolin Chlorestic Liquid Crystal display was 500 mm, significantly longer than Sony electronic ink display, 491 mm. Screen angle for Kolin was 127.4 degrees, significantly greater than that of Sony, 120.0 degrees. Various light sources revealed no significant effect on viewing distances; nevertheless, they showed significant effect on screen angles. The screen angle for sunlight lamp (D65) was similar to that of fluorescent lamp (TL84), but greater than that of tungsten lamp (F). Ambient illumination and E-paper type had significant effects on viewing distance and screen angle. The higher the ambient illumination was, the longer the viewing distance and the lesser the screen angle. Character size had significant effect on viewing distances: the larger the character size, the longer the viewing distance. The results of this study indicated that the viewing distance for E-Paper was similar to that of visual display terminal (VDT) at around 500 mm, but greater than normal paper at about 360 mm. The mean screen angle was around 123.7 degrees, which in terms of viewing angle is 29.5 degrees below horizontal eye level. This result is similar to the general suggested viewing angle between 20 degrees and 50 degrees below the horizontal line of sight.     

Differential effects of head-mounted displays on visual performance

Head-mounted displays (HMDs) virtually augment the visual world to aid visual task completion. Three types of HMDs were compared [look around (LA); optical see-through with organic light emitting diodes and virtual retinal display] to determine whether LA, leaving the observer functionally monocular, is inferior. Response times and error rates were determined for a combined visual search and Go-NoGo task. The costs of switching between displays were assessed separately. Finally, HMD effects on basic visual functions were quantified. Effects of HMDs on visual search and Go-NoGo task were small, but for LA display-switching costs for the Go-NoGo-task the effects were pronounced. Basic visual functions were most affected for LA (reduced visual acuity and visual field sensitivity, inaccurate vergence movements and absent stereo-vision). LA involved comparatively high switching costs for the Go-NoGo task, which might indicate reduced processing of external control cues. Reduced basic visual functions are a likely cause of this effect.     

Smaller pupil size and better proofreading performance with positive than with negative polarity displays

The ‘positive polarity advantage’ describes the fact that reading performance is better for dark text on light background (positive polarity) than for light text on dark background (negative polarity). We investigated the underlying mechanism by assessing pupil size and proofreading performance when reading positive and negative polarity texts. In particular, we tested the display luminance hypothesis which postulates that the typically greater brightness of positive compared to negative polarity displays leads to smaller pupil sizes and, hence, a sharper retinal image and better perception of detail. Indeed, pupil sizes were smaller and proofreading performance was better with positive than with negative polarity displays. The results are compatible with the hypothesis that the positive polarity advantage is an effect of display luminance. Limitations of the study are being discussed.     

Effects of font size and font style of Traditional Chinese characters on readability on smartphones

This study investigated the effects of Traditional-Chinese character sizes and typefaces on both reading time and subjective preference when participants used 5.5-inch smartphones without limiting their viewing distance. An experiment of 3 × 3 completely randomized design with eighteen replicates was employed. One hundred and sixty-two participants performed reading comprehension tasks and subjective preference ratings which were used to measure the readability of nine design combinations. The results suggested that the smaller character size was better than the larger one for reading tasks. Additionally, the most favorite typeface was the Kai or Hei style. These findings might be more appropriate than those of previous studies to be generalized for Traditional-Chinese typographic design on smartphones because the real conditions of operating smartphones were considered in this study.     

Laptop displays performance: Compliance assessment with visual ergonomics requirements

The use of display devices such as smartphones, tablets, laptops is now massive and continuous in everyday life. It, therefore, becomes increasingly important to be aware of the performance of these devices, not only in terms of the tasks to be performed but also in terms of interaction with humans and therefore knows any possible effect on the ergonomics of vision. Following previous research activities conducted by the authors on the assessment of the visual ergonomics at video display terminal workstations, the aim of this study is to evaluate the ergonomics of human-system interaction of laptop displays. In details, a sample of 57 laptop displays is analyzed in accordance with the requirements of the EN ISO 9241-3xx series of international standards related to the display luminance, luminance ratio, contrast non-uniformity. An extensive luminance measurement campaign was carried out using a special pattern that allowed to measure the luminance in 13 different areas of the displays. The results obtained with this activity showed a great luminance variability between different displays. Almost all the displays are able to emit high levels of display luminance, and almost all the displays meet the requirement of contrast non-uniformity. However, several devices did not meet the recommended values of luminance ratio. Furthermore, the authors created a simplified graph to allow a rapid evaluation of the performance of the displays. This method could be periodically used in practice in order to evaluate the residual performance level.     

Ergonomic evaluation of electronic paper: Influences of anti‐reflection surface treatment,illumination, and curvature on legibility and visual fatigue

Abstract— The intent of this study is to investigate some critical factors that affect legibility and visual fatigue while reading on an electronic‐paper display in terms of ergonomics. Anti‐reflection surface treatment, ambient illumination, and bending curvature are taken into account to evaluate their effects by using the method of letter‐search task. The results showed that the surface treatment with high degrees of anti‐reflection significantly improved the legibility and reduces visual fatigue. Thus, electronic‐paper manufacturers may choose a much better surface treatment in order to meet ergonomic demand. In addition, the findings in the present study also indicate that subjects reported less visual fatigue on a bending surface of a visual display unit, in comparison with a plane surface. It is proven that these ergonomic evaluations for electronic paper provide manufactures with useful information to design suitable products for users.     

Relationship between phoria and visual fatigue in autostereoscopic 3D displays

Many people complain about visual fatigue arising from viewing three‐dimensional (3D) displays. This paper investigates relationship between visual fatigue and viewers' phoria for viewing autostereoscopic 3D displays. Visual fatigue is evaluated through subjective symptoms with a questionnaire and optometric indicators comprising fusion range as well as accommodation convergence/accommodation (AC/A) ratio to measure the variation in visual functions. A screening test is adopted to divide the subjects into two groups based on whether they suffer from phoria. Then a 2 × 2 × 2 mixed design experiment is conducted with display type, viewing stage, and visual state as factors to examine visual fatigue during viewing session. The results show that phoria subjects obtain more severe visual fatigue than normal on subjective evaluation. The normal subjects reveal a more marked difference with phoria in fusion range and AC/A ratio after viewing 3D video clip. Fusion range can significantly distinguish between the two‐dimensional (2D) and 3D condition as well as between the pre‐ and post‐viewing stages. The sensitivity and specificity of fusion range is higher than AC/A ratio with respect to viewing of 3D contents, so it is more appropriate as an optometric indicator of visual fatigue for autostereoscopic 3D displays.     

Investigation of legibility and visual fatigue for simulated flexible electronic paper under various surface treatments and ambient illumination conditions

This study employs simulated electronic paper to investigate critical issues and focuses on improving legibility of display and reducing users' visual fatigue. Three critical factors - choice of surface treatment, ambient illumination, and bending curvature - are evaluated through the method of a letter-search task. The results show that subjects performed better on legibility and felt less visual fatigue with an anti-glare treatment. Choosing the better anti-glare treatment instead of the anti-reflection series can save significant cost for manufacturers. In addition, ambient lighting of 1500 lux is more appropriate for reading on electronic paper than an environment with extreme illumination (e.g., 8000 lux). The present study also found that curvature had no impact on legibility or visual fatigue. These evaluations of simulated electronic paper may provide manufacturers useful information in fulfilling ergonomic requirements for product design.     

Color displays and flexible displays using quick‐response liquid‐powder technology for electronic paper

Abstract— Color displays and flexible displays that use electronic liquid powder have been developed. Novel types of color displays using either a colored powder or a color filter are discussed. We have also developed a flexible display with low‐cost substrate films with a high‐throughput roll‐to‐roll manufacturing method. These technologies enable a QR‐LPD to be widely used as an electronic‐paper display.     

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.     

Effects of virtual lighting on visual performance and eye fatigue

This study is designed to determine whether differences in eye fatigue and visual performance can be shown under varying virtual industrial lighting conditions. It is based on the results of studies of more traditional video display terminal (VDT) tasks reported in the literature. One experiment was designed to determine if the effects of virtual lighting on eye fatigue and visual performance in a simulated virtual industrial environment are similar to some other VDT tasks with varying luminance contrast. Results of a test of 20 participants in a vigilance task show that there is a significant difference in performance and eye fatigue in the virtual environment with varying virtual light conditions. These results may help designers see that performance in some virtual “lighting” conditions, for some tasks, is consistent with that in the real. However, due to the difficulties of determining the appropriate virtual objects to be considered for the luminance measures, additional research is needed to be able to generalize the results to other industrial training scenarios. A second experiment was intended to test for the luminance decrement in a VDT that was shown in recent literature. The results would have potential implications for the experiment that included a vigilance task. However, the results showed that the luminance decrement demonstrated in recent literature did not occur. These results suggest that the equipment used in the present experiments should not cause difficulty in interpreting the results of the vigilance task. © 2002 Wiley Periodicals, Inc.