A 510‐kb SOG‐DRAM for mobile displays with embedded frame memories

Abstract— A system‐on‐glass (SOG) dynamic random access memory (DRAM), which enables the implementation of frame‐memory‐integrated displays, has been developed. A dynamic one‐transistor‐one‐capacitor memory cell, which has a data retention time of over 16.6 msec, and a compression/decompression (CODEC) circuit were developed to reduce the layout area and power. The CODEC enables an 18‐bit/pixel color display, while reducing the memory capacity from 18 to 12 bits/pixel. A frame‐memory macro was created by combining the SOG‐DRAM with an embedded controller that enables independent access for writing and reading. Its operation was verified by chip measurement and demonstration as a frame‐memory operation of 262k‐color QCIF+ displays. The work reported in this paper was the first step to creating a Zero‐Chip Display with an integrated frame memory, and it proved the concept was feasible.     

Method for predicting motion artifacts in matrix displays

Abstract— A method is proposed to measure and characterize motion artifacts in matrix displays. By using a fast, V(λ)‐corrected photodiode and a data‐acquisition system, accurate measurements of the temporal luminance behavior (step response) are recorded. The motion artifacts of LCDs and PDP displays are predicted from these measurements using the properties of the human‐visual system. The method is validated with perceptual evaluation experiments, for which a new evaluation protocol is established. In the end, new measures are proposed to quantify the motion‐rendering performance of these matrix displays.     

A knowledge-based system for generating informative responses to indirect database queries

The objective of this study is to develop a knowledge-base framework for generatingcooperative answers to indirect queries. Anindirect query can be considered as a nonstandard database query in which a user did not specify explicitly the information request. In a cooperative query answering system, a user's indirect query should be answered with an informative response, either anaffirmative response or anegative response, which is generated on the basis of the inference of the user's information request and the reformulation of the users' indirect query.This paper presents methods for inferring users' intended actions, determining users' information requirements, and for automatically reformulating indirect queries into direct queries. The inference process is carried out on the basis of a user model, calluser action model, as well as the query context. Two kinds ofinformative responses, i.e.affirmative responses andnegative responses can be generated by arule-based approach.     

In‐field evaluation of the modulation transfer function and the signal‐to‐noise ratio of electronic‐display devices

Abstract— This paper describes a charged‐coupled device (CCD) camera, which was developed for in‐field evaluation of the image quality of electronic‐display devices [such as cathode‐ray tubes (CRTs) and liquid‐crystal displays (LCDs)] used for medical applications. Contrary to traditional cameras for display‐image‐quality evaluation, this CCD camera does not require a sophisticated x‐y‐z translation stage for mounting and adjustment. Instead, it is handheld and pressed by gentle pressure against the display screen. It is controlled by a software package which was originally developed for display calibration according to the DICOM 14 gray‐scale standard display function (GSDF). This software package controls the camera gain when measurements are made at different display luminance, display test patterns, performs image analysis and displays the results of the measurements and calculations. The work concentrated on the measurement of modulation transfer function (MTF) and of signal‐to‐noise ratio (SNR) per display pixel. The MTF is derived from the Fourier transform of the line spread function (LSF). The single‐display‐pixel SNR is derived from the integration of the noise power spectrum (NPS) of a camera image taken of a display with a uniform luminance. It is demonstrated that the device can produce repeatable results in terms of MTF and SNR. MTFs were measured on three monochrome CRTs and five monochrome LCDs in order to study repeatability and similar quantities. The MTF was measured on a 5‐Mpixel LCD yielding values that lie within 3.5% of the average MTF at the Nyquist frequency and 4.0% of the maximum total sharpness (∫ MTF² df). The MTF was also measured on a 9‐Mpixel LCD, yielding values that lie within 9.0% of the average MTF at the Nyquist frequency and 8.0% of the maximum total sharpness. The SNR was measured eight times on a 3‐Mpixel monochrome LCD at nine digital driving levels (DDLs). At a DDL of 185, the mean SNR was 15.694 and the standard deviation (Stdv) was 0.587. At a DDL of 65, the mean SNR was 5.675 and Stdv was 0.120.     

A novel driving method for field sequential color using an OCB TFT‐LCD

We report a new technique for the design of field‐sequential‐color liquid‐crystal displays (FS‐LCDs), which maximizes the liquid‐crystal response,t_LC, by dividing the display area into as few sub‐areas,N, as possible. We obtained the following results: (1) ^tLC increased as N increased, although saturation tended to occur. Increasing N from 1 to 2 gave the largest increase in ^tLC. (2) ^tLC was maximized by dividing the display area unequally.     

Inverse display characterization: A two‐step parametric model for digital displays

Abstract— A simple additivity model is often used as a basic model for digital‐display characterization. However, such a simple model cannot satisfy the needs of demanding color‐management applications all the time. On the other hand, systematic sampling of the color space and 3‐D interpolation is an expensive method in terms of measurement and computation time when precision is needed. This paper presents an enhanced method to characterize the XYZ‐to‐RGB transform of a digital display. This parametric method exploits the independence between the luminance variation of the electro‐optic response and the colorimetric responses for certain display types. The model is generally applicable to digital displays, including 3‐DMD projectors, single DMDs, CRTs, LCDs, etc., if the independence condition is satisfied. While the problem to solve is a 3‐D‐to‐3‐D transformation (from XYZ to RGB), the proposed parametric model is the composition of a 2‐D transform followed by a 1‐D transform. The 2‐D transform manages the chromatic aspects and, in succession, the 1‐D transform manages the luminance variations. This parametric digital model is applicable in the field of color management, with the objective of characterizing digital displays and applying a reference look such as a film look.     

Learning adaptive contrast combinations for visual saliency detection

Visual saliency detection plays a significant role in the fields of computer vision. In this paper, we introduce a novel saliency detection method based on weighted linear multiple kernel learning (WLMKL) framework, which is able to adaptively combine different contrast measurements in a supervised manner. As most influential factor is contrast operation in bottom-up visual saliency, an average weighted corner-surround contrast (AWCSC) is first designed to measure local visual saliency. Combined with common-used center-surrounding contrast (CESC) and global contrast (GC), three types of contrast operations are fed into our WLMKL framework to produce the final saliency map. We show that the assigned weights for each contrast feature maps are always normalized in our WLMKL formulation. In addition, the proposed approach benefits from the advantages of the contribution of each individual contrast feature maps, yielding more robust and accurate saliency maps. We evaluated our method for two main visual saliency detection tasks: human fixed eye prediction and salient object detection. The extensive experimental results show the effectiveness of the proposed model, and demonstrate the integration is superior than individual subcomponent.

     

3‐D crosstalk and luminance uniformity from angular luminance profiles of multiview autostereoscopic 3‐D displays

Abstract— Autostereoscopic 3‐D display technologies enable a more immersive media experience by adding real depth to the visual content. However, the method used for the creation of a sensation of depth or stereo illusion contains several display design and content‐related issues that need to be carefully considered to maintain sufficient image quality. Conventionally, methods used for 3‐D image‐quality evaluations have been based on subjective testing. Optical measurements, in addition to subjective testing, can be used as an efficient tool for 3‐D display characterization. Objective characterization methods for autostereoscopic displays have been developed. How parameters affecting stereo image quality can be defined and measured, and how their effect on the stereo image quality can be evaluated have been investigated. Developed characterization methods are based on empirically gathered data. In this paper, previously presented methodology for two‐view displays is extended to cover autostereoscopic multiview displays. A distinction between displays where the change in content occurs in clear steps when the user moves in front of the display, and displays where the apparent movement of the objects is more continuous as a function of the head movement is made. Definitions for 3‐D luminance and luminance uniformity, which are equally important, as well as 3‐D crosstalk, which is the dominant factor in the evaluations of the perceived 3‐D image quality, is focused upon.     

The present and future of electronic paper

Abstract— With the rise of electrophoretic‐display media from several sources, the world is opening up for new uses of electronic displays. Where “immersive reading” used to be a task strictly reserved for paper, displays can now fulfill that role. Many challenges still remain, such as full‐color photograph‐like performance and video speeds. However, in view of recent accomplishments showing near‐video‐speed switching and potential for full color, after electrophoretic displays obtain a slice of the reading market, application of these developments will take us a significant step towards full‐color animated paper‐like displays. The developments that have led to the presence of electronic paper in the market today will be described, and developments that are about to happen will be discussed.     

Contrast effect in evaluating the sense of presence for wide displays

Abstract— To evaluate the relationship between visual angle and the sense of presence for wide displays, two experiments were conducted in which the visual angle (ranging from 30 to 100°) was manipulated as a between‐ and within‐subjects factor, respectively. Two‐hundred subjects participated in both experiments. In the within‐subjects evaluation, presence scores increased as the visual angle widened, while those in the between‐subjects evaluation did not increase significantly for a wide visual angle. It can be concluded that “contrast effect,” i.e., a bias caused by comparing different visual angles, greatly affects the ratings of sense of presence.     

Optical response of helix‐free FLC: Continuous gray scale,fastest response,and lowest control voltage

Electro‐optical response of a display cells with novel helix‐free FLC (differently, compensated helix ferroelectric—CHF) is considered. Predominance of the shear viscosity in the soliton mode of FLC director reorientation leads to weakening the temperature dependence of the response time. Increasing the electric field frequency expands this temperature interval, and it is 15°C… 45°C for the frequency about 3 kHz at ±1.5 V in a display cell with FLC viscosity of 0.7 P. Increasing the rotational viscosity up to 1.0 P provides the increase of speed ability due to Maxwell's nature of energy dissipation. The optical response time of 24 µs and light modulation frequency of 7 kHz were achieved at the amplitude of control voltage pulses ±1.5 V. Thus, like NLC based cells, the experimental samples of CHF based display cells at the same (or even lower) value of voltage and electric field tension (1–2 V/µm) show the continuous gray scale and hysteresis‐free modulation characteristic (up to 5 kHz) but can provide 40–50 times (!) higher speed. These break‐through results characterize CHF as the most high‐speed materials for future 3D displays and displays using field sequential color technique, including FLCoS and TFT addressed, as well as displays with new functional properties.     

A photographic technique for assessing the viewing‐angle performance of liquid‐crystal displays

Abstract— Liquid‐crystal displays (LCDs) have notable variation in luminance and perceived contrast as a function of the angle from which they are viewed. Though this is an important performance issue for LCDs, most evaluation techniques for assessing this variation have been limited to laboratory settings. This study demonstrates the use of a photographic technique for such an evaluation. The technique is based on an actively cooled charge‐coupled‐device (CCD) detector in combination with a macro lens covering a circular angular range (θ) of ±42.5°. The camera was used to evaluate the luminance and perceived contrast properties of an LCD. Uniform field images corresponding to 17 equally spaced gray‐scale values in the digital driving level (DDL) range of the display system were acquired. The 12‐bit gray‐scale digital images produced by the camera were converted to luminance units (cd/m²) via the measured luminance vs. DDL response function of the camera. The changes in perceived contrast as a function of viewing angle were derived from the Barten model of the gray‐scale response of the human‐visual system using the methods proposed by the AAPM TG18 Report. The results of this photographic technique were compared to measurements acquired from a similar display using a Fourier‐optics‐based luminance meter. The results of the two methods generally agreed to within 5%. The photographic methods used were found to be accurate and robust for in‐field assessment of the angular response of LCDs over the FOV of the camera.     

LCD models to analyze and simulate motion artifacts

Abstract— In this paper, two models to evaluate the temporal behavior of liquid‐crystal displays are described: a model assuming a linear display behavior and a model that incorporates non‐linear effects. For the linear temporal model, it can be predicted that the response time starts to contribute to motion blur when it is longer than one‐sixth of the hold time and becomes dominant when it is longer than eight times the hold time. The non‐linear model can be used to visualize the appearance of effects that cannot be determined via linear system theory. Also, some means to reduce display artifacts are described and its impact is illustrated. Although the main focus in this article is on the temporal behavior of liquid‐crystal displays, the spatial properties defined by the pixel structure can be simulated as well. A formula for the spatio‐temporal display behavior is given, which can be evaluated numerically to simulate the perceived image for arbitrary image‐sequence input material.     

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.     

A Framework for Interactive Hypertexture Modelling

Hypertexturing can be a powerful way of adding rich geometric details to surfaces at low memory cost by using a procedural three‐dimensional (3D) space distortion. However, this special kind of texturing technique still raises a major problem: the efficient control of the visual result. In this paper, we introduce a framework for interactive hypertexture modelling. This framework is based on two contributions. First, we propose a reformulation of the density modulation function. Our density modulation is based on the notion of shape transfer function. This function, which can be easily edited by users, allows us to control in an intuitive way the visual appearance of the geometric details resulting from the space distortion. Second, we propose to use a hybrid surface and volume‐point‐based representation in order to be able to dynamically hypertexture arbitrary objects at interactive frame rates. The rendering consists in a combined splat‐ and raycasting‐based direct volume rendering technique. The splats are used to model the volumetric object while raycasting allows us to add the details. An experimental study on users shows that our approach improves the design of hypertextures and yet preserves their procedural nature.     

The luminance resolution characteristics of multi‐primary‐color display

Abstract— In this paper, the resolution characteristics of multi‐primary‐color (MPC) display systems are analyzed. That four‐primary‐color (4PC) displays can increase the effective resolution for achromatic images in the luminance domain by a factor of two as compared to conventional RGB‐based displays with MPC‐specialized subpixel rendering, which is proposed in this paper, is demonstrated. Five‐ and six‐primary‐color (5PC and 6PC) display systems can reproduce denser luminance data than conventional RGB‐based display systems and solve a problem of MPC displays, viz. an increase of production costs and a decrease in the aperture ratio caused by increasing the number of subpixels in one pixel. This is an essential advantage of MPC display systems, which is related to the combination of the proposed color‐filter architecture and image processing. Thus, a completely new advantage of MPC display systems, in addition to their well‐known capabilities of color reproduction and power saving, is proposed.     

Characterizing displays by their temporal aperture: A theoretical framework

Abstract— The spatio‐temporal aperture and sample rate of a video display determines both the static and dynamic resolution of the video signal that is rendered. The dynamic display characteristics like the visibility of large‐area flicker, motion judder, and motion blur can be derived from the frame rate and the temporal extent of the pixel aperture (i.e., the temporal aperture). For example, liquid‐crystal displays (LCDs) have an aperture that is relatively small in the spatial dimension and wide in the temporal domain. Consequently, moving objects displayed on an LCD suffer from motion blur. Especially in TV applications, the temporal dimension has a large impact on the overall picture quality. The temporal aperture, together with the frame rate, is shown to predict the amount of perceived large‐area flicker, motion judder, and motion blur and also the performance of motion‐blur reduction algorithms for LCDs. From this analysis it is further determined how to obtain the optimal temporal aperture of a television display, for which not only properties of the human visual system (HVS), but also the properties of the video signal have to be taken into account.     

A submillisecond‐response liquid crystal for color sequential projection displays

We report a new LC with low viscosity and high clearing point (T_c ~102 °C) for color‐sequential projection displays. Using a 1.95‐µm mixed‐mode twisted nematic cell, the averaged gray‐to‐gray response time is less than 1 ms, which is ~3.6× faster than the current state of the art. Such a mixed‐mode twisted nematic liquid‐crystal‐on‐silicon can be used for near‐to‐eye wearable projection displays and head‐up displays in vehicles.     

Display modulation by Fourier transform: A preferred method

Abstract— A preferred method for determining the grating modulation of a rear‐projection display using a grating image and Fourier analysis is prescribed. This method is insensitive to spatial image noise and is in better correspondence with the response of the human visual system than is the standard technique. This method is not limited to rear‐projection displays and can be applied to any display technology.     

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.