The effects of LCD anisotropy on the visual performance of users of different ages

OBJECTIVE: The present study examined the visual discrimination speed and accuracy while using an LCD and a CRT display. BACKGROUND: LCDs have ergonomic advantages, but their main disadvantage is that they provide inconsistent photometric measures depending on the viewing angle (anisotropy). METHOD: Independent variables were screen type (LCD and CRT), viewing angle (0 degrees, 11 degrees, 41 degrees, 50 degrees, and 56 degrees) and user's age (teenagers, young adults, and middle-aged adults). Dependent variables were speed and accuracy in a visual discrimination task and user's ratings. RESULTS: The results corroborated the negative impact of LCD anisotropy. Visual discrimination times were by 7.6% slower when an LCD was used instead of a CRT. Performance differences increased with increasing viewing angle for both screens, but performance decrements were larger for the LCD. Young adults showed the best visual performance, as compared with teenagers and middle-aged adults. Effects of anisotropy were found for all age groups, although the performance of middle-aged adults was affected more when extended viewing angles were adopted. CONCLUSION: LCD anisotropy is a limiting factor for visual performance, especially in work settings where fast and accurate reactions are necessary. APPLICATION: The outcomes of this research allow ergonomic guidelines for electronic reading.     

LCD versus CRT displays: a comparison of visual search performance for colored symbols

Visual search performance for tactical symbols was examined with liquid-crystal (LCD) and cathode-ray tube (CRT) displays. Twenty-four adult participants (19 men, 5 women; mean age 41 years) searched for navy tactical display symbols on a map background. LCD and CRT displays of similar size and resolution (52 cm diagonal, 1280 x 1024 pixels) were used. Viewing angle (0 degrees vs. 60 degrees of azimuth), set size, target color (blue, red, or white), target presence, and search type (feature vs. conjunction) were also manipulated. Participants showed reduced sensitivity for red and blue symbols viewed 60 degrees off axis with the LCD relative to on-axis LCD, or to the CRT on or off axis. Colored symbols viewed off axis on the LCD produced longer response times in feature search and lower search efficiency in conjunction search. The results argue against the use of current LCD technology when off-axis viewing is likely and color coding is used.     

Effect of moving pictures on visual task performance and fatigue using 4K OLED and LCD TVs

This study compared the effects of 4K organic light‐emitting diode (OLED) and liquid‐crystal display (LCD) TVs on human visual task performance and fatigue when viewing moving pictures. In experiments conducted, subjects were asked to locate 35 icons among a total of 276 on‐screen icons at four moving picture speeds. From the results obtained, it was determined that OLED TVs (emissive type) exhibit superior characteristics for hit rate and false alarm rate compared with LCD TVs (non‐emissive‐type). The evaluation results of a simulator sickness questionnaire administered to ascertain fatigue levels also indicated that OLED TVs induce relatively little fatigue at fast‐moving picture speeds of 10 ppf or more compared with LCD TVs. Thus, this study confirms that OLED TVs, given their ultrafast response time characteristics, are superior in terms of moving picture images to LCD TVs.     

Proof-reading texts on screen and paper

This study examined the speed and accuracy of proof-reading a text presented on a CRT, relative to performance with print on paper. Two groups of 16 people each proof-read four published texts, roughly 1500 words per text For all readers, half the texts were presented as print on paper and half were presented on a 12 in. CRT screen. The two groups differed in whether the errors found in the screened text were recorded on the screen or on paper. The results suggested that the method of recording errors on the screen was quickly learned, but that both speed and accuracy were impaired when the text was presented on the screen. The implications of this for refereeing electronic journals is discussed.     

Proof-reading texts on screen and paper

Abstract

This study examined the speed and accuracy of proof-reading a text presented on a CRT, relative to performance with print on paper. Two groups of 16 people each proof-read four published texts, roughly 1500 words per text For all readers, half the texts were presented as print on paper and half were presented on a 12 in. CRT screen. The two groups differed in whether the errors found in the screened text were recorded on the screen or on paper. The results suggested that the method of recording errors on the screen was quickly learned, but that both speed and accuracy were impaired when the text was presented on the screen. The implications of this for refereeing electronic journals is discussed.     

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.     

低照度液晶屏幕图像增强算法

为解决目前自然场景文本识别系统文字识别率较低的问题,从识别图像的质量角度分析,发现用相机拍摄的带有液晶屏幕的图像,易受到光照或屏幕本身显示问题影响,成像质量低,难以辨别屏幕内信息。传统的解决方法如使用retinex算法进行图像增强时,由于retinex算法本身的局限性,对于光照不均的图像,会出现光晕现象。针对此问题,本文提出基于同态滤波的去光晕retinex算法来进行光照的校正,首先使用改进的同态滤波算法对图像进行不同程度的滤波处理,校正光照,处理后图像再使用改进的retinex算法进行图像增强,则可以避免光晕现象。实验结果表明,本文方法可以有效提高低照度液晶屏幕图像的视觉效果,优于传统的retinex算法,无光晕现象产生,进而提高自然场景文本识别系统的识别准确率。     

Effect of image size on the color appearance of image reproductions using colorimetrically calibrated LCD and DLP displays

Abstract— Archiving images of cultural heritage based on spectral imaging techniques is an active research area in imaging science. Original and reproduced art are usually viewed under quite different viewing conditions. One of the interesting differences in viewing condition is size difference. This leads to different surrounds and adaptation states. In order to investigate the effect of size in color perception of rendered images, a visual experiment was conducted using a colorimetrically characterized digital projector and LCD. An image was rendered and projected on the screen. The same image was processed using various algorithms followed by rendering for the LCD. These LCD rendered images, by definition, were considerably smaller than the projected image. Using a paired‐comparison method, the effect of image size was investigated using a colorimetric image of Georges Seurat's, “Sunday Afternoon on the Island of La Grande Jatte — 1884.” The image rendered for an LCD with a linear increase in lightness resulted in a closer match to the image projected on screen than an original colorimetrically rendered image and was perceived as a more accurate reproduction than the majority of algorithms tested.     

Survey of actual viewing conditions at home and appropriate luminance of LCD‐TV screens

Abstract— To understand actual viewing conditions at home is important for TV design. And the preferred luminance level of LCD TVs under actual viewing conditions is also important in order to obtain both good picture quality and low power consumption. The actual viewing conditions of households and the preferred luminance levels was investigated. In a field test of 83 households, the display luminance, screen illuminance, and viewing locations were measured on site. In laboratory experiments, young and elderly subjects adjusted the luminance of an LCD‐TV screen to their preferred levels under different screen illuminance levels, angular screen sizes, and average luminance levels (ALL) of the images. As a result, two equations, which represent the preferred luminance level of LCD‐TV screens corresponding to different viewing conditions for young and elderly subjects were obtained. When the ALL of the images was 25% and the screen illuminance and angular screen size were set at 100 lx and 20°, respectively, the preferred luminance was 1 60 cd/m² for the young subjects and 248 cd/m² for the elderly subjects. By using the setting of the preferred luminance of an LCD TV under actual viewing conditions, it is possible to conserve energy consumption.     

Visual comfort in using different VDT screens

In order to meet the goal of user comfort of information displays, visual problems of video display terminal (VDT) work were studied through the analysis of visual functions in two experiments. Eye movement analysis, in Experiment 1, revealed that VDT operators had to move their eyes 2.5 times faster than traditional clerical workers. Lens accommodation, pupil size, and subjective visual comfort were investigated in Experiment 2. A significant correlation was found between the velocity of lens accommodation and the subjective visual comfort while viewing seven different displays (r = .809). A positive‐type cathode‐ray tube (CRT), which has dark characters on a light background, was ascertained to be the most appropriate display type, while working with a liquid crystal display (LCD) was considered to be the least visually comfortable, with the lowest accommodative velocity.     

Theory and Practice of the Stereo-View on the CRT Screen

Of the various kinds of research on the Virtual Reality and GIS,stereo-view is one of the key technologies.The following two aspects are covered in this paper,(1) Physiological fundamental of the natural binocular stereo-vision,theory of 3D color TV and the stereo-view on the CRT screen are presented,especially the theory of widely adopted Time-Division System is introduced.(2)The preliminary practice for using the stereo-view technology on the screen to the terrain visual simulation is described,and the paper shows how to use 3DS to construct a movable real stereo terrain perspective by taking DTM data as the first hand information for the purpose of terrain visual simulation.     

Industrial inspection performance depends on both viewing distance and oculomotor characteristics.

The influence of viewing distance and individual differences in the oculomotor resting states (dark vergence and dark focus) on both inspection performance and visual fatigue was investigated by asking 24 college students to perform a visual inspection task for 40 min twice, once with a 20 cm viewing distance and once with a 60 cm viewing distance. During the task participants visually searched enlarged images of contact lenses for six different types of defects. Lens images were presented at a constant visual angle (17.5 degrees) on a CRT. Inspection performance varied significantly across the two viewing distances: participants spent on average more than twice as much time inspecting individual lenses in the near condition (mean = 18.32 s lens(-1)) than in the far condition (mean = 7.25 s lens(-1)). Participants also reported greater visual fatigue in the near condition than in the far condition. At both viewing distances, participants who experienced relatively large inward shifts in dark vergence also tended to be slow inspectors. Neither inspection performance nor measures of fatigue were related to dark focus. These results support existing evidence against the use of near viewing distances and suggest that an oculomotor mechanism links inspection performance and visual fatigue to viewing distance.     

Effect of slow display on detectability when browsing large image datasets

Abstract— In this work, the effect of display temporal characteristics on detectability of signals was studied by comparing detection performance with a slow liquid‐crystal‐display (LCD) monitor and a fast, cathode‐ray‐tube (CRT) monitor when browsing multi‐slice image datasets in stack‐mode presentation. Thirteen readers evaluated 200 image sequence pairs in a two‐alternative forced choice experiment. The image sets consisted of three‐dimensional cluster lumpy backgrounds and were presented to the readers in two display devices: a three‐million‐pixel medical color LCD and a color desktop CRT. For the LCD, many inter‐gray‐level transitions are on the order of 50–60 msec, which was almost twice the frame time. The CRT had 2–5‐msec inter‐gray‐level transitions. The reader study was performed with a graphical‐user interface programmed using direct calls to OpenGL libraries to precisely control the browsing speed. The results were analyzed in terms of the difference in reader performance for each reader and each display, between a browsing speed of 20 and 50 frames per sec (fps). Average reader performance difference between 20 and 50 fps was measured to be 0.049 and 0.156 for the CRT and LCD monitors, respectively. The corresponding drop in reader performance associated with slow display was 0.11.     

Effects of output display and control—display gain on human performance in interactive systems

Abstract

Human performance comparisons on interactive systems were drawn between output displays (CRT and LCD) across settings of control-display gain. Empirical evidence was sought in light of the common feeling in the user community that motor-sensory tasks are more difficult on a system equipped with an LCD display vs. a CRT display. In a routine target acquisition task using a mouse, movement times were 34% longer and motor-sensory bandwidth was 25% less when the output display was an LCD vs. a CRT. No significant difference in error rates was found. Control-display (C-D) gain was tested as a possible confounding factor; however, no interaction effect was found. There was a significant, opposing main effect for C-D gain on movement lime and error rates, illustrating the difficulty in optimizing C-D gain on the basis of movement time alone.     

Effects of output display and control—display gain on human performance in interactive systems

Human performance comparisons on interactive systems were drawn between output displays (CRT and LCD) across settings of control-display gain. Empirical evidence was sought in light of the common feeling in the user community that motor-sensory tasks are more difficult on a system equipped with an LCD display vs. a CRT display. In a routine target acquisition task using a mouse, movement times were 34% longer and motor-sensory bandwidth was 25% less when the output display was an LCD vs. a CRT. No significant difference in error rates was found. Control-display (C-D) gain was tested as a possible confounding factor; however, no interaction effect was found. There was a significant, opposing main effect for C-D gain on movement lime and error rates, illustrating the difficulty in optimizing C-D gain on the basis of movement time alone.     

The benefits of more electronic screen space on students’ retention of material in classroom lectures

Many lecture halls today have two or more screens to be used by instructors for lectures with computer-supported visual aids. Typically, this additional screen real estate is not used to display additional information; rather a single stream of information is projected on all screens. We describe a controlled laboratory study that empirically assesses the effect on students learning of using the increased classroom screen real estate to project an additional stream of information. We measured how well participants learned from a two-stream presentation compared to a one-stream presentation duplicated on both screens. Data indicate that using extra screen real estate can indeed improve learning. In particular, learning was most improved when pertinent prior information was shown alongside currently explained information. There is also evidence that visual comparisons were improved with parallel viewing using extra screen real estate. Subjective data gathered from participants showed a strong preference for learning with two streams of content over a regular one-stream presentation.     

低对比度下的智能电表液晶屏外观检测研究

为了解决智能电表（Smart Meter）自动化检测系统中的关键技术问题,提出了在低对比度环境下智能电表液晶屏外观质量检测的处理方法。实现液晶屏区域的准确分割;采用基于小波变换的图像增强算法在低对比度环境下突出液晶屏上的字符信息;利用形态学梯度对字符信息进行重构,最终实现对液晶屏的外观质量检测。实验结果表明,该处理方法能够有效地解决低对比度环境下的智能电表液晶屏外观质量检测问题,检测可靠性高,具有较高工程应用价值。     

Technologies towards patterned optical foils applied to transflective LCDs

Abstract— For better front‐of‐screen performance for transflective LCDs, a technology with extra free optimization parameters for the optical stack is needed. Thin wet coatable retarders which enable adjustment of the optical activity on the (sub)pixel level have been developed. Isotropic domains have been created in nematic retardation films by thermal patterning or photopatterning. Employing such a patterned retarder in a transflective LCD leads to an LCD that is lighter and thinner with good reflectivity, high transmission, and low chromaticity at all gray levels and wide viewing angles. The patterned thin‐film technology has been proven to be versatile and applicable in various LCD designs.     

Next‐generation mobile LCDs with in‐cell retarders

Abstract— In‐cell retarders can be a major breakthrough for mobile LCDs. When a patterned in‐cell retarder replaces the external retarders on transflective LCDs, brighter and thinner transflective LCDs with lower power consumption and wider viewing angle can be obtained. Additionally, when in‐cell retarders are applied in reflective LCDs, the thickness of the LCD is considerably reduced without affecting the optical performance of the reflective LCD. This paper presents the technology needed to make in‐cell retarders and the performance of reflective and transflective LCDs with in‐cell retarders.