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.     

Preference survey of curvature of large‐size displays

This study investigated the aesthetic judgment of large‐size curved displays and found out the most preferred radius of them. For the survey, 1:1 scale curved display mock‐ups were presented to subjects, and the displays were made of acrylic frame with various sizes and curvatures. The subjects were asked to assess their preference for the displays in both aesthetic appeal and visual comfort at a distance of 2.5 m. The survey results showed that the most preferred radius of curvature varies depending on the display size, and it increases as the display size becomes larger. For 55‐in. displays, the most preferred radius of curvature was found as 2000 mm across the contents attached on the displays. With regard to the 65‐ and 75‐in. displays, the subjects' preference was increased to 3000 mm that lightly varied depending on the presented contents.     

Advanced compensation technologies for large‐sized UHD OLED TVs

In this paper, we present novel organic light‐emitting diode (OLED) display panel compensation technologies for large‐sized ultra‐high‐definition OLED TVs considering variations of threshold voltage, mobility, channel size, OLED efficiency, and OLED uniformity. Using these technologies, we have successfully launched 55‐, 65‐ and 77‐in. ultra‐high‐definition OLED TVs.     

Reading experience with curved hand‐held displays

Abstract— The aim of this study was to measure reading experiences on curved paper‐like displays. The experimental materials were mockups that consisted of printed paper attached to a curved plastic surface. The experiment participants held the mockups in their hands and evaluated the reading experience with them. Twelve font sizes, two curvature magnitudes, and two curvature directions were used in the experiment. The results showed that reading text on a curved surface was easier when the curvature direction is perpendicular to the text direction. It was also found that concave surfaces were regarded as better in cases where the text direction was the same as the curvature direction.     

Discrete Distortion in Triangulated 3‐Manifolds

We introduce a novel notion, that we call discrete distortion, for a triangulated 3‐manifold. Discrete distortion naturally generalizes the notion of concentrated curvature defined for triangulated surfaces and provides a powerful tool to understand the local geometry and topology of 3‐manifolds. Discrete distortion can be viewed as a discrete approach to Ricci curvature for singular flat manifolds. We distinguish between two kinds of distortion, namely, vertex distortion, which is associated with the vertices of the tetrahedral mesh decomposing the 3‐manifold, and bond distortion, which is associated with the edges of the tetrahedral mesh. We investigate properties of vertex and bond distortions. As an example, we visualize vertex distortion on manifold hypersurfaces in R⁴ defined by a scalar field on a 3D mesh. distance fields.     

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.     

Improving content visibility for high‐ambient‐illumination viewable display and energy‐saving display

Abstract— Nowadays, low‐contrast viewing of LC displays (LCDs) occurs very often, which includes the viewing of mobile LCDs at high ambient illumination and the viewing of LCDs at low‐power mode. These cases result in low‐content visibility and low contrast, leading to an unpleasant viewing experience. In this paper, a technique to improve the perceived contrast and visibility of images at low‐contrast viewing conditions is proposed. The proposed approach enhances image brightness with content and ambient adaptive image brightening and highlights visual parts and boundaries with non‐photorealistic rendering. The proposed technique enables longer battery life for mobile LC devices and makes mobile LC devices viewable at high ambient illumination. It also enables TVs with extreme low‐power consumption and smart‐grid responsive TVs.     

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.     

A quantitative measurement of LCD and PDP TVs for human visual preference and fatigue

This study was conducted by subjective and objective measurement, to clarify the complex relationships among human visual preference and fatigue of major Flat Panel Display TVs with related physical and physiological factors. In the subjective measurement, comparison tests with 24 subjects were conducted and the semantic differential method with factor analysis was carried out for six TVs with different room luminance and length of watching time. The comparison test yielded identification of the most preferable display, which showed little connection with the TV luminance for any length of watching time and room luminance. From the statistical factor analysis of semantic differential method, significant factors were extracted for describing human visual preference. In the objective measurement, the eye motion tracking camera was used to detect the eye response and thus generated physiological data corroborated the significant factors extracted from the subjective measurement. This study allows the human perceptual preference and fatigue of electronic displays to be quantitatively measured with psychological and physiological factors and will tell which parameters are significant and guide the manufacturer in making the optimum TVs.     

A4‐sized flexible ferroelectric liquid‐crystal displays with micro color filters

Abstract— We demonstrated an A4‐paper‐sized flexible ferroelectric liquid‐crystal (FLC) color displays fabricated by using a new plastic‐substrate‐based process which was developed for large‐sized devices. Finely patterned color filters and ITO electrodes were formed on a plastic substrate by a transfer method to avoid surface roughness and thermal distortion of the substrate, which induce disordering of the FLC molecular alignment. The thickness of an FLC/monomer solution sandwiched by two plastic‐film substrates was well controlled over a large area by using flexographic printing and lamination techniques. Molecular‐aligned polymer walls and fibers were formed in the FLC by a two‐step photopolymerization‐induced phase‐separation method using UV‐light irradiation. A fabricated A4‐sized flexible‐sheet display for color‐segment driving was able to exhibit color images even when it was bent.     

Designing interfaces for explicit preference elicitation: a user-centered investigation of preference representation and elicitation process

Two problems may arise when an intelligent (recommender) system elicits users?? preferences. First, there may be a mismatch between the quantitative preference representations in most preference models and the users?? mental preference models. Giving exact numbers, e.g., such as ??I like 30?days of vacation 2.5?times better than 28?days?? is difficult for people. Second, the elicitation process can greatly influence the acquired model (e.g., people may prefer different options based on whether a choice is represented as a loss or gain). We explored these issues in three studies. In the first experiment we presented users with different preference elicitation methods and found that cognitively less demanding methods were perceived low in effort and high in liking. However, for methods enabling users to be more expressive, the perceived effort was not an indicator of how much the methods were liked. We thus hypothesized that users are willing to spend more effort if the feedback mechanism enables them to be more expressive. We examined this hypothesis in two follow-up studies. In the second experiment, we explored the trade-off between giving detailed preference feedback and effort. We found that familiarity with and opinion about an item are important factors mediating this trade-off. Additionally, affective feedback was preferred over a finer grained one-dimensional rating scale for giving additional detail. In the third study, we explored the influence of the interface on the elicitation process in a participatory set-up. People considered it helpful to be able to explore the link between their interests, preferences and the desirability of outcomes. We also confirmed that people do not want to spend additional effort in cases where it seemed unnecessary. Based on the findings, we propose four design guidelines to foster interface design of preference elicitation from a user view.     

A novel lens cap designed for the RGB LEDs installed in an ultra‐thin and directly lit backlight unit of large‐sized LCD TVs

Abstract— The objective of this study is to design a novel cone‐shaped lens cap on LEDs in order to achieve high optical efficiency in an ultra‐thin directly lit RGB LED backlight unit (BLU) for large‐sized LCD TVs. The use of the novel lens cap could play the role of a diffuser, a low light‐efficiency component in a BLU, in order to gain higher efficiency and simultaneously provide satisfactory uniformity in light distribution. The novel cone‐shaped lens is coated with aluminum on the outside surface of the cone for mirroring effects to reflect most of the LED emitted light horizontally and then reflect the light at the BLU boundaries, and then, finally to the output plane. In this way, bright spots on the output plane of the BLU can be avoided, leading to increased uniformity. Simulations were conducted to design and optimize varied aspects of the designed lens and BLU, including the cone angle of the proposed lens and the LED spacing (pitch). To further achieve color balance, a known Genetic Algorithm is used to search for the optimal angular placement of each RGB LED, resulting in better color balance. Finally, a prototype BLU for large‐sized 37‐in. LCD TVs with the proposed lens was built to verify the expected performance.     

Scaling‐up PECVD system for large‐sized substrate processing

Abstract— With the prevailing trend of large‐panel TFT monitors and, most recently, LCD TVs, large‐sized‐substrate processing is becoming the mainstream of TFT‐LCD production. To enable this trend of ever‐increasing large‐area processing, a multiple generations of PECVD systems for volume production has been successfully developed. This paper discusses the scaling‐up challenges from the equipment manufacturer's perspective, with the focus on process scalability, system design optimization, productivity enhancement, and cost‐of‐ownership reduction.     

Novel WV film for wide‐viewing‐angle TN‐mode LCDs

Abstract— A new optical compensation film refered to as WV‐EA film for TN‐mode TFT‐LCDs has been developed, resulting in higher contrast ratio, wider‐viewing‐angle characteristics, and improved color shift than their predecessors, especially in the horizontal direction. These features of the new WV film were achieved as a result of haze reduction and optimizing the optical characteristics of the polymerized discotic material layer and TAC film. These features are suitable for large‐sized and wide‐aspect‐ratio LCD monitors and TVs.     

White‐LED backlight control for motion‐blur reduction and power minimization in large LCD TVs

Abstract— A 1‐D LED‐backlight‐scanning technique and a 2‐D local‐dimming technique for large LCD TVs are presented. These techniques not only reduce the motion‐blur artifacts by means of impulse representation of images in video, but also increase the static contrast ratio by means of local dimming in the image(s). Both techniques exploit a unique feature of an LED backlight in large LCD TVs in which the whole panel is divided into a pre‐defined number of regions such that the luminance in each region is independently controllable. The proposed techniques are implemented in a Xilinx FPGA and demonstrated on a Samsung 40‐in. LCD TV. Measurement results show that the proposed techniques significantly reduce the motion‐blur artifacts, enhance the static contrast ratio by about 3×, and reduce the power consumption by 10% on average.     

Weak‐Tie Support Network Preference and Perceived Life Stress Among Participants in Health‐Related,Computer‐Mediated Support Groups

The study reported here examines characteristics of weak‐tie support network preference among members of health‐related computer‐mediated support groups. Drawing on weak‐tie support network theory and socioemotional selectivity theory, participants' age and health condition were assessed as predictors of weak ties support network preference. Relationships between the dimensions of weak‐tie support network preference and perceived stress also were evaluated. The results demonstrated that age was negatively associated with a preference for weak‐tie support, and that participants not facing a terminal illness were more likely than those preferring a terminal illness to prefer weak‐tie support. The objective utility and greater‐perceived‐risks dimensions of weak‐tie support network preference were significant predictors of perceived stress. The implications of these findings for health communication interventions are discussed.     

A study on the relationships among hand muscles and form factors of large-screen curved mobile devices

The aim of this study is to determine the effect of form factors (curvature rate, depth) of mobile devices on hand comfort when using large-screen curved mobile devices. To that end, four muscles (APB, APL, FDI, EDC) were selected and mockups for experiment were developed with four curvature rate levels (flat/100/200/300R) and five depth levels (3/5/7/9/11 mm). User experiment was conducted using three interactions (tapping, dragging, and texting) that usually take place on smartphones. EMG signal of each participant was measured. Combination of curvature and depth could maximize the physical comfort of hands and fingers through the experiment so that the interaction effect between form factors and tasks could be identified. Our results revealed that only APL and FDI had statistically significant muscle activity amounts across the curvature rates. With respect to effect of depth, all four muscles showed statistically significant difference in muscle activity. Moreover, results from the interaction effect among task levels of two tasks (target location of tapping and direction of dragging) and two form factors showed no interaction effect in either tapping or texting. The results of this study could be used to determine the optimal range for form factors of curved screen mobile devices in terms of physical comfort of the hand while using large-screen devices.     

Shape from texture for smooth curved surfaces in perspective projection

Projective distortion of surface texture observed in a perspective image can provide direct information about the shape of the underlying surface. Previous theories have generally concerned planar surfaces; this paper presents a systematic analysis of first- and second-order texture distortion cues for the case of a smooth, curved surface. In particular, several kinds of texture gradients are analyzed and are related to surface orientation and surface curvature. The local estimates obtained from these cues can be integrated to obtain a global surface shape, and it is shown that the two surfaces resulting from the well-known tilt ambiguity in the local foreshortening cue typically have qualitatively different shapes. As an example of a practical application of the analysis, a shape-from-texture algorithm based on local orientation-selective filtering is described, and some experimental results are shown.     

Optimal surface parameterization using inverse curvature map

Mesh parameterization is a fundamental technique in computer graphics. Our paper focuses on solving the problem of finding the best discrete conformal mapping that also minimizes area distortion. Firstly, we deduce an exact analytical differential formula to represent area distortion by curvature change in the discrete conformal mapping, giving a dynamic Poisson equation. Our result shows the curvature map is invertible. Furthermore, we give the explicit Jacobi matrix of the inverse curvature map. Secondly, we formulate the task of computing conformal parameterizations with least area distortions as a constrained nonlinear optimization problem in curvature space. We deduce explicit conditions for the optima. Thirdly, we give an energy form to measure the area distortions, and show it has a unique global minimum. We use this to design an efficient algorithm, called free boundary curvature diffusion, which is guaranteed to converge to the global minimum. This result proves the common belief that optimal parameterization with least area distortion has a unique solution and can be achieved by free boundary conformal mapping. Major theoretical results and practical algorithms are presented for optimal parameterization based on the inverse curvature map. Comparisons are conducted with existing methods and using different energies. Novel parameterization applications are also introduced.     

The importance of native panel contrast and local dimming density on perceived image quality of high dynamic range displays

We evaluated the perceived image quality of High Dynamic Range (HDR) content rendered using different types of local dimming and organic light‐emitting diode (OLED) displays. Using an OLED display that is capable of achieving high contrast at a pixel level, we emulated local dimming displays to evaluate their image quality. In a set of subjective experiments, observers compared HDR images and videos rendered with different local dimming densities and native panel contrast. There was a strong effect of panel contrast on perceived quality and also a strong trend toward preference for a larger number of dimming zones. We also evaluated the panel contrast and number of local dimming zones necessary to achieve image quality comparable with OLED. The findings of these experiments demonstrated that the use of a high‐contrast panel remains of critical importance. Also, the preference for panel rendering mode remains robust to normal levels of indoor ambient light.