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.     

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.     

Luminance effects influencing perception of 3‐D TV imagery

Abstract— This study investigates whether screen luminance or ambient illumination has a significant effect on the perception of 3‐D TV imagery for static images and dynamic films. Two types of stimuli were shown on a multi‐view stereoscopic display: the static image, which included computer‐generated and photographic images, and dynamic film, which contained real‐life and animation images. In each treatment with a different level of screen luminance, subjects completed psychophysical and physiological measurements and subjective comfort evaluations. The results showed that when subjects viewed 3‐D static images, the ambient illumination affected psychophysical visual fatigue and screen luminance had a significant effect on subjective comfort evaluation and visual discrimination performance. However, when subjects viewed 3‐D dynamic films, screen luminance was the major factor causing psychophysical visual fatigue, and ambient illumination significantly affected subjective comfort evaluation. The outcomes contribute to knowledge concerning the suitable viewing conditions for the 3‐D viewing experience. Future work will explore the intolerance threshold of the lowest display luminance or the effect of decomposition of the screen on other physiological measurements.     

Effects of illumination conditions on preferred viewing distance of portable liquid‐crystal television

This study explored the effect of TV size, light source, and ambient illumination on the preferred viewing distance of portable liquid‐crystal‐display televisions. Results showed that the mean preferred viewing distance was 1389 mm. TV size had significant effects on preferred viewing distance. The larger the screen size, the greater the preferred viewing distance, at around 6.7–14.7 times the width of the screen (W). Light sources revealed no significant effect on preferred viewing distance. The effect of ambient illumination on preferred viewing distance was significant. The higher the ambient illumination was, the longer the preferred viewing distance.     

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.     

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.     

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.     

Adapting softcopy color reproduction to ambient illumination

Abstract— The perceived colors of an image seen on a self‐luminous display are affected by ambient illumination. The ambient light reflected from the display faceplate is mixed with the image‐forming light emitted by the display. In addition to this direct physical effect of viewing flare, ambient illumination causes perceptual changes by affecting the adaptation state of the viewer's visual system. This paper first discusses these effects and how they can be compensated, outlining a display system able to adjust its output based on prevailing lighting conditions. The emphasis is on compensating for the perceptual effects of viewing conditions by means of color‐appearance modeling. The effects of varying the degree of chromatic adaptation parameter D and the surround compensation parameters c and N_c of the CIECAM97s color‐appearance model were studied in psychophysical experiments. In these memory‐based paired comparison experiments, the observers judged the appearance of images shown on an LCD under three different ambient‐illumination conditions. The dependence of the optimal parameter values on the level of ambient illumination was evident. The results of the final experiment, using a category scaling technique, showed the benefit of using the color‐appearance model with the optimized parameters in compensating for the perceptual changes caused by varying ambient illumination.     

IPS‐mode dynamic LCD‐TV realization with low black luminance and high contrast by adaptive dynamic image control technology

Abstract— In this paper, an active backlight control technology and a data‐processing algorithm has been developed to improve the image quality in IPS‐mode LCD TVs. The image‐blinking problem caused by repeatedly abrupt changes in the backlight luminance was solved by using algorithms [Fba (flexible‐boundary algorithm) and Cfa (cumulative feedback algorithm)] and an optimized number of backlight dimming steps based on human perception. In the IPS‐mode 42‐in. TFT‐LCD panel, the dynamic contrast ratio can be more than twice the typical level by means of a lower black luminance and a higher white luminance. Additionally, the power consumption and LCD temperature were lowered.     

Angular dependence of the performance of stereoscopic liquid‐crystal‐display (LCD) television using shutter glasses (SG)

Abstract— 3‐D cross‐talk typically represents the ratio of image overlap between the left and right views. For stereoscopic LCDs using shutter‐glasses technology, 3‐D cross‐talk for stereoscopic LCD TV with a diagonal size of 46 in. and vertical alignment (VA) mode was measured to change from 1% to 10% when the stereoscopic display is rotated around the vertical axis. Input signals consist of the left and right images that include patterns of different amounts of binocular disparity and various gray levels. Ghost‐like artifacts are observed. Furthermore, intensities of these artifacts are observed to change as the stereoscopic display is rotated about the vertical axis. The temporal luminance of the LCD used in stereoscopic TV was found to be dependent on the viewing direction and can be considered as one cause of the phenomenon of angular dependence of performance for stereoscopic displays.     

Preferred viewing distance of liquid crystal high-definition television

This study explored the effect of TV size, illumination, and viewing angle on preferred viewing distance in high-definition liquid crystal display televisions (HDTV). Results showed that the mean preferred viewing distance was 2856 mm. TV size and illumination significantly affected preferred viewing distance. The larger the screen size, the greater the preferred viewing distance, at around 3-4 times the width of the screen (W). The greater the illumination, the greater the preferred viewing distance. Viewing angle also correlated significantly with preferred viewing distance. The more deflected from direct frontal view, the shorter the preferred viewing distance seemed to be.     

Quantification model of proper curvature for large‐sized curved TVs

We present a feasible modeling method to estimate the proper curvature for large‐sized curved TVs. We especially focused on two factors – preference and perceived distortion – to be considered to determine the proper curvature. The preference includes a number of advantages that people expect to fulfill the possibilities of a more immersive image and sense of realism from curved display. On the other hand, the perceived distortion means the side effects that people can notice uncomfortable feeling caused by the shape of a curved one. In order to find out how two factors would be different as a number of conditions like curvature, size, and viewing angle change, a series of subjective assessments were conducted. The evaluation results show that both the preference and perceived distortion vary with the conditions considerably. We performed the statistical analysis based on the results and proposed the quantification model of proper curvature, which has higher preference and less perceived distortion, for various‐sized curved TVs.     

Laser‐based multi‐user 3‐D display

Abstract— The development of a multi‐user stereoscopic display that does not require the use of special glasses (autostereoscopic), and that enables a large degree of freedom of viewer movement and requires only the minimum amount of information (a stereo pair) for the displays described. The optics comprise an RGB holographic laser projector that is controlled by the output of a multi‐target head‐position head tracker, an optical assembly that converts the projector output into steerable exit pupils, and a screen assembly comprising a single liquid‐crystal display (LCD) and image multiplexing screen. A stereo image pair is produced on the LCD by simultaneously displaying left and right images on alternate rows of pixels. Novel steering optics that replace the conventional backlight are used to direct viewing regions, referred to as exit pupils, to the appropriate viewers' eyes. The results obtained from the first version of the display, where the illumination source consists of several thousand white LEDs, are given and the current status of the latest prototype being constructed on the basis of these results is described. The work indicates that a laser‐based head‐tracking display can provide the basis for the next generation of 3‐D display.     

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.     

LCDs for TV applications

Abstract— Super IPS (S‐IPS) technology has intrinsic advantages in several aspects required for TV applications. Particularly, the wide‐viewing‐angle property and fast gray‐to‐gray response time of S‐IPS LCDs are both necessary requirements for family and individual use for LCD TVs. Given these benefits and other advantages S‐IPS provides, LG.Philips LCD has developed high‐performance S‐IPS LCDs for TV, which have now become competitive with plasma‐display panels (PDPs), in addition to other modes of LCD TVs as well as CRTs. This article will discuss why S‐IPS technology is the leading choice for LCD‐TV applications.     

Image‐color‐quality modeling under various surround conditions for a 2‐in. mobile transmissive LCD

Abstract— This study aims to develop an image‐color‐quality (ICQ) model for a 2‐in. mobile transmissive liquid‐crystal display (LCD). A hypothetical framework for ICQ judgment was made to visually assess ICQ based the cognitive processes of the human visual system (HVS), and then an illumination adaptive ICQ model applicable for various surround conditions was developed. The memory color reproduction ratio (MCRR) of a locally adapted region of interest in a complex image reproduced on a mobile display was first computed. The colorfulness index and luminance contrast for all of the pixels in the image were then calculated by a global adaptation process. Finally, an ICQ model including all of the three attributes was developed under dark conditions using an assessed set of psychophysical data. The model gave more accurate performance than the mean accuracy for all of the observers. It was also visually tested under three different outdoor conditions, including overcast, bright, and very bright conditions, and the illuminance level range was from 7000 to 35,000 to 70,000 lx. The effect of outdoor illumination could be quantified as an exponential decay function and the ICQ model could be extended to cover a wide variety of outdoor illuminations conditions.     

Preferred balance between luminance and color gamut in mobile displays

Abstract— To improve the image quality of a mobile display, the balance between color‐gamut size and luminance was studied in two subjective experiments. The first experiment was performed during the Asian Society for Information Display (ASID) conference in Nanjing, February 2004. Nearly 600 participants ranked the quality of images displayed for fixed combinations of color‐gamut size and display luminance on small color supertwisted nematic (CSTN) and thin‐film transistor (TFT) twistednematic (TN) displays. In the second experiment, a broader range of color‐gamut sizes and luminance levels were simulated on a cathode‐ray tube (CRT) display, and 20 participants were asked to score perceived image quality. The results of these experiments were used to model image quality as a function of color‐gamut size and display luminance for images differing in the level of chromaticity of their content. This model can be used to estimate the increase in luminance required to compensate for a reduction in color‐gamut size.     

Depth‐ and viewing‐angle‐enhanced 3‐D/2‐D switchable display system with high contrast ratio using multiple display devices and a lens array

Abstract— An improved 3‐D/2‐D switchable display system with enhanced depth and viewing angle by adding two LCD panels to an integral imaging system has been realized. The proposed system uses the see‐through property of an LCD panel and displays multiple sets of elemental images on the LCD panels to integrate them on multiple locations simultaneously. As a result, the depth of the 3‐D image can be enhanced. For wide viewing angles, the time‐multiplexing method was adopted by displaying mask patterns on the front LCD panel. In addition, another technique to increase the contrast ratio of the proposed system has also been developed. Some experimental results will be provided.     

Optimization of liquid crystals for television

Abstract— LCD TVs have dramatically improved in performance during the last 2 years. At the same time, the sale prices decreased by more than 50%. Together with the introduction of digital terrestrial broadcasting, this resulted in increasing sales of LCD TVs. This paper gives an overview of the main liquid‐crystal display (LCD) technologies used for TVs. We discuss key materials, synthesis, structural property relationships, and the optimization of LC mixture properties. For all technologies, we have achieved fast‐switching LC mixtures (16 msec). Novel materials for LC mixtures for the next generation of superior performance LCD TVs with 8‐msec switching times are shown.     

Reduced cross‐talk in shutter‐glass‐based stereoscopic LCD

Abstract— It is expected that 3‐D will be the next step in the enhanced viewing experience. At present, there are two competing 3‐D technologies for glasses‐based consumer TVs: active shutter glasses and passive polarized glasses. With the ongoing reduction in response time of liquid‐crystal displays (LCDs), this article will focus on shutter‐glass‐based stereoscopic LCDs. In this paper, the properties of such a display system is described and it is demonstrated that by adding a line‐scanning backlight, the cross‐talk can be reduced to less than 1.4%, allowing for excellent 3‐D portrayal. For images of extreme contrast, this is perceivable, but not judged annoying by a panel of expert viewers. Which characteristics of the display and shutter glasses that should be optimized to create an inexpensive, cross‐talk‐free, 3‐D LCD are discussed.