High‐performance 55‐in. diagonal WXGA PDP with extended ALIS technology

Abstract— We have developed a high‐performance 55‐in. diagonal WXGA PDP module with a novel structure by using Extended ALIS (Alternate Lighting of Surfaces) technology. The new cell structure that uses the common bus electrode concept was invented with a new driving scheme aimed toward progressive lighting. A new method of reducing dynamic false contour (DFC), motion adaptive subfield coding, was also developed. The newly developed 55‐in. WXGA panel has a 1000‐cd/m² peak luminance and a 160‐cd/m² full‐screen white luminance with a 9000 K color temperature at a 350‐W display power consumption.     

A study on reducing image‐sticking artifacts in wide‐screen TFT‐LCD monitors

Abstract— In order to improve the image quality of flat‐panel displays, the image retention of a display has to be reduced. But at the same time, display devices also have to produce durable images while they are used for long periods of time in a single session. To achieve high‐quality images with reduced image sticking in TFT‐LCD devices, we have increased their voltage‐holding ratio (VHR). This technology ensures the achievement of durable images over long periods of time and also reduces the image‐sticking problem. There are many ways to achieve increased VHR. In terms of the characteristics of the TFT devices, reducing the leakage‐current effects is the most frequently applied method in the display industry.     

Ambient‐light‐adaptive image quality enhancement for full‐color e‐paper displays using a saturation‐based tone‐mapping method

Full‐color e‐paper displays that have a small color gamut encounter image tone distortions and contour artifacts in high‐saturation regions. To solve these issues, in this paper, we comprehensively measure the colorimetric responses of input image signals and demonstrate that the perceptual colorfulness in terms of chroma abnormally declines when the input saturation is beyond a certain value. Accordingly, saturation‐based tone‐mapping curves are developed to map the abnormal high saturation to the range that the display is able to normally render. By testing several test charts and natural images, the recoveries of the original image tones and the removals of the contour artifacts are experimentally verified. More important, by discussing how to conduct a database of tone‐mapping curves for different ambient lights and utilize the database for an unknown ambient light, the proposed method is proven to be completely ambient light adaptive.     

Two-stage dither to enhance gray scales based on real-time motion detection in plasma display panel

In order to reduce gray scale loss in low and middle-high gray scale ranges which are caused by inverse gamma conversion and limited gray scale method for dynamic false contour (DFC) improvement, respectively, and enhance gray scales both in static and moving regions of an image, two-stage dither based on real-time motion detection method is proposed. Firstly, the image is divided into blocks, and the motion state of each image block is detected according to real-time motion detection method. So limited gray scale method to improve DFC can only be used in moving image blocks. Then, ordered dither and random dither combined with minor pixel separation (MPS) are used to improve gray scale loss caused by inverse gamma conversion and limited gray scale method, respectively. The experimental results show that motion detection can be implemented easily and the detection accuracy is more than 99.3%. The gray scales in moving and static image regions are all expressed smoothly while DFC is markedly improved.     

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.     

Stereoscopic 3‐D display with optical correction for the reduction of the discrepancy between accommodation and convergence

Abstract— This paper describes a method for reducing the discrepancy between accommodation and convergence when viewing stereoscopic 3‐D images. The method uses a newly developed stereoscopic 3‐D display system with a telecentric optical system and a mobile LCD. The examination of a mono‐focal lens showed that a correction lens having the appropriate refractive power and conditions for presenting stereoscopic 3‐D images clearly reduces the discrepancy between accommodation and convergence. The authors also developed a stereoscopic 3‐D display that uses dynamic optical correction to reduce the discrepancy between accommodation and convergence. The display equalizes the theoretical points of accommodation and convergence. The purpose of the development was to expand the regeneration range of a stereoscopic 3‐D image having the appropriate accommodation. An evaluation of the developed display showed that it resolves the discrepancy between convergence and accommodation.     

A novel pixel memory using integrated voltage‐loss‐compensation (VLC) circuit for ultra‐low‐power TFT‐LCDs

Abstract— A novel pixel memory using an integrated voltage‐loss‐compensation (VLC) circuit has been proposed for ultra‐low‐power TFT‐LCDs, which can increase the number of gray‐scale levels for a single subpixel using an analog voltage gray‐scale technique. The new pixel with a VLC circuit is integrated under a small reflective electrode in a high‐transmissive aperture‐ratio (39%) 3.17‐in. HVGA transflective panel by using a standard low‐temperature‐polysilicon process based on 1.5‐μm rules. No additional process steps are required. The VLC circuit in each pixel enables simultaneous refresh with a very small change in voltage, resulting in a two‐orders‐of‐magnitude reduction in circuit power for a 64‐color image display. The advanced transflective TFT‐LCD using the newly proposed pixel can display high‐quality multi‐color images anytime and anywhere, due to its low power consumption and good outdoor readability.     

Efficient Depth‐of‐Field Rendering with Adaptive Sampling and Multiscale Reconstruction

Depth‐of‐field is one of the most crucial rendering effects for synthesizing photorealistic images. Unfortunately, this effect is also extremely costly. It can take hundreds to thousands of samples to achieve noise‐free results using Monte Carlo integration. This paper introduces an efficient adaptive depth‐of‐field rendering algorithm that achieves noise‐free results using significantly fewer samples. Our algorithm consists of two main phases: adaptive sampling and image reconstruction. In the adaptive sampling phase, the adaptive sample density is determined by a ‘blur‐size’ map and ‘pixel‐variance’ map computed in the initialization. In the image reconstruction phase, based on the blur‐size map, we use a novel multiscale reconstruction filter to dramatically reduce the noise in the defocused areas where the sampled radiance has high variance. Because of the efficiency of this new filter, only a few samples are required. With the combination of the adaptive sampler and the multiscale filter, our algorithm renders near‐reference quality depth‐of‐field images with significantly fewer samples than previous techniques.     

A cascaded Mura defect detection method based on mean shift and level set algorithm for active‐matrix OLED display panel

Active‐matrix OLED (AMOLED), as the next‐generation display technology, is being commercially promoted rapidly. And Mura defects occur unavoidable during different phases of the AMOLED panel production process. In this paper, a cascaded Mura detection method leveraging the mean shift and the level set algorithm is proposed. First, we use the mean shift algorithm to find the general contour of the Mura defects that circumvent the issue in established level set segmentation approach wherein the use of the local image information is sensitive to the initial contour. Then, we improve the level set model that combines global and local information to segment Mura defects accurately. The integration of local image information can levitate the challenges in the global image model, which cannot separate the local intensity inhomogeneity and texture background individually. The experiments show that the cascaded method has a superior capability in terms of both accuracy and efficiency.     

A psychophysical study of improvements in motion‐image quality by using high frame rates

Abstract— The ideal frame rate for the highest motion‐image quality with respect to blur and jerkiness is presented. In order to determine the requirements for avoiding these impairments, motion images from a high‐speed camera and computer graphics were combined with a high‐speed display to perform a psychophysical evaluation. The camera, operating at 1000 fps, and image processing were used to simulate various frame rates and shutter speeds, and a 480‐Hz CRT display was used to present motion images simulating various frame rates and time characteristics of the display. Subjects were asked to evaluate the difference in quality between motion images at various frame rates. A frame rate of 480 fps was chosen to be an appropriate reference frame rate that, as a first estimation, enables coverage up to the human‐dynamic‐resolution (HDR) limit based on another experiment using real moving charts. The results show that a frame rate of 120 fps provides good improvement compared to that of 60 fps, and that the maximum improvement beyond which evaluation is saturated is found at about 240 fps for representative standard‐resolution natural images.     

Confined‐error‐diffusion algorithm for flat‐panel display

Abstract— The reduction of a structural pattern at specific gray levels caused by digital halftone methods is the subject of this paper. This problem is more severe in some flat‐panel displays because their black levels typically are brighter than other display blocks. A patented halftone algorithm, confined error diffusion (CED), that confines the error‐carry within the dither mask is described and extended. First, the CED algorithm that dynamically applies random error diffusion or the ordered‐dither method, depending upon image content, is described in detail. Finally, we propose an advanced CED algorithm for improving the gradation characteristics of the CED algorithm. The performance of the proposed algorithms is compared to the experimental results for natural test images. In order to verify the halftone quality, a structural similarity measure for color images by taking into account the interrelation between color channels is proposed, and the results based on the proposed method, the color similarity measure method, is given.     

Evaluation of HDR tone‐mapping algorithms using a high‐dynamic‐range display to emulate real scenes

Abstract— Current HDR display technology approaches the dynamic‐range capabilities of the fully adapted human visual system. As such, this technology has potential for performing as a surrogate for real‐world scenes in the perceptual evaluation of high‐dynamic‐range (HDR) image‐reproduction algorithms that aim to map HDR scenes to the limited dynamic ranges available in typical display and print technology. Compared with direct image assessment in comparison with real‐world scenes, it is clear that use of HDR display technology has the benefit of simplicity in experimental design while maintaining the HDR of the original scene. To evaluate this potential application of HDR display technology, seven published versions of well‐known HDR tone‐mapping algorithms were benchmarked for perceptual rendering accuracy against each of four real‐world scenes constructed in the laboratory and against corresponding images on an HDR display. The results illustrate that visual assessments obtained from the HDR display and those obtained from real‐world scenes are in good agreement, validating the potential for HDR display technology as an evaluation tool in this context.     

Efficacy of global dimming backlight and high‐contrast liquid crystal panel for high‐dynamic‐range displays

Using an RGB organic light‐emitting diode display to emulate liquid crystal display systems, we examined the efficacy of different global dimming strategies for cinematic content. A global dimming solution with smoothed transitions was preferred over solutions using a static backlight level or the highly aggressive frame‐by‐frame backlight adjustment scheme. We compared two such smoothing approaches, one making use of causal data, and another using future information (which could be available via latency or dynamic metadata) and did observe some opportunities for an improved experience, but found the causal data to be a competitive approach. We also evaluated the importance of native panel contrast and how global dimming compares to local dimming approaches. For most content tested, a global dimming display with a high‐contrast liquid crystal panel was judged as being equivalent or more preferred to a full‐array local dimming display with a low‐contrast panel. These results build on the existing evidence that native panel contrast remains one of the strongest predictors of high‐dynamic‐range image quality even as backlight technologies continue to improve.     

High‐quality direct‐view display combining multiple integral 3D images

This paper proposes a method for combining multiple integral three‐dimensional (3D) images using direct‐view displays to obtain high‐quality results. A multi‐image combining optical system (MICOS) is used to enlarge and combine multiple integral 3D images without gaps. An optical design with a simple lens configuration that does not require a diffuser plate prevents the deterioration in resolution resulting from lens arrangement errors and the diffuser plate. An experiment was performed to compare a previously developed method with the proposed method, and the latter showed a significant improvement in image quality. A method for expanding the effective viewing angle of the proposed optical design was also developed, and its effectiveness was confirmed experimentally. A prototype device of the proposed optical design was constructed using a high‐density organic light‐emitting diode (OLED) panel with 8K resolution and 1058 ppi pixel density to achieve 311 (H) × 175 (V) elemental images, a viewing angle of 20.6° in both the horizontal and vertical directions, and a display size of 9.1 in. In addition, the proposed optical design enabled making device considerably thinner, ie, with a thickness of only 47 mm.     

Two‐parallax‐barriers‐based autostereoscopic liquid‐crystal display without cross‐talk

Abstract— An autostereoscopic liquid‐crystal display (LCD) consists of two parallax barriers and an LCD including a liquid‐crystal panel, and a backlight panel is proposed. Parallax barrier 1 is located between the backlight panel and the liquid‐crystal panel, and Parallax barrier 2 is located between the liquid‐crystal panel and viewers. The operation principle of the autostereoscopic display and the calculation equations for the parallax barriers are described in detail. The autostereoscopic LCD was developed and produces high‐quality stereoscopic images without cross‐talk at the optimal viewing distance and less cross‐talk than a conventional one based on one parallax barrier at other viewing distances.     

Design of carbon nanotubes for large‐area electron field‐emission cathodes

Abstract— Electron field‐emission displays offer a viable option for the next generation of flat‐panel screens. Boasting high‐quality images in terms of good color saturation, fast refresh rate, and high brightness, these displays have the potential to offer above and beyond what the current market leaders, LCD and plasma. However, for the realization of such a new display disrupting the incumbent LCD and plasma displays, not only does the image quality need to be better, but fabrication costs and suitable manufacturing processes need to be in place at reduced cost. Many viable cathode materials have been proposed in recent years, one of which being the use of carbon nanotubes (CNTs) in various forms (aligned growth, screen printing, and polymer matrix). In this review, a series of recent experiments investigating the field‐emission characteristics of carbon‐nanotube systems for possible use in the display industry is presented.     

A high image quality organic light‐emitting diode display with motion blur reduction for ultrahigh resolution and premium TVs

In this paper, we present a high image quality organic light‐emitting diode (OLED) display with motion blur reduction technology. Our latest work includes driving method that reduces motion blur using an adaptive black data insertion, brightness compensation technology, the simple structure pixel with low capacitance coupling for horizontal noise, and the multifunction integrated gate driver. The moving picture response time (MPRT) value of the OLED display panel with a fast response time was significantly affected by the frame frequency and the compensation driving method. The MPRT value of the large‐size OLED display panels was significantly decreased by using the integrated gate driver circuit with an MPRT reduction method. The decrease in the MPRT value originated from the turning of the emitting pixels off in advance resulting from providing black data. The integrated gate drivers were designed to achieve the normal display, the black data insertion, and the compensation mode. The MPRT value of the 65‐in. ultrahigh‐definition (UHD) OLED panels was decreased to 3.4 ms by using an integrated gate driver circuit. The motion blur of large‐size OLED display panels was significantly reduced due to a decrease in the MPRT value.     

Noise estimation and reduction on five medical liquid‐crystal displays

Abstract— Liquid‐crystal displays (LCDs) are replacing cathode‐ray tube (CRT) displays as primary diagnostic viewing devices in clinics. They exhibit higher spatial noise than CRTs, which can interfere with diagnosis and reduce the efficiency especially when subtle abnormalities are presented. A study by the authors on LCD spatial noise has recently been reported. A high‐quality CCD camera was used to acquire images from the LCD. Noise properties were estimated from the digital‐camera images. Then, an error‐diffusion‐based operation was applied to reduce the display spatial noise. This paper presents the noise estimation and reduction results on five different medical‐grade LCDs using the same study protocol. These five different LCDs vary in terms of matrix size, pixel size, pixel structure, and vendors. The purpose of this work is to demonstrate that the LCD spatial‐noise estimation and reduction scheme proposed earlier by the authors is valid, robust, and necessary for various medicalgrade LCDs used in clinics today.     

Depth image‐based rendering for multiview generation

Abstract— Techniques for 3‐D display have evolved from stereoscopic 3‐D systems to multiview 3‐D systems, which provide images corresponding to different viewpoints. Currently, new technology is required for application in multiview display systems that use input‐source formats such as 2‐D images to generate virtual‐view images of multiple viewpoints. Due to the changes in viewpoints, occlusion regions of the original image become disoccluded, resulting in problems related to the restoration of output image information that is not contained in the input image. In this paper, a method for generating multiview images through a two‐step process is proposed: (1) depth‐map refinement and (2) disoccluded‐area estimation and restoration. The first step, depth‐map processing, removes depth‐map noise, compensates for mismatches between RGB and depth, and preserves the boundaries and object shapes. The second step, disoccluded‐area estimation and restoration, predicts the disoccluded area by using disparity and restores information about the area by using information about neighboring frames that are most similar to the occlusion area. Finally, multiview rendering generates virtual‐view images by using a directional rendering algorithm with boundary blending.     

A controller design for micro‐cup active‐matrix electrophoretic displays

Abstract— The active‐matrix electrophoretic display (AMEPD) has been commonly used for the applications of smart handheld reading devices such as e‐books and e‐newspapers. This paper presents a controller IC design for the AMEPD backend system which reduces the total hardware cost compared to that of the conventional design. By contrast, this study also provides a driving method for image displays. The prototyped controller is connected to a 6‐in. AMEPD panel, and good display quality has demonstrated the effectiveness of the proposed controller design.