Optically adjustable display color gamut in time-sequential displays using LED/Laser light sources

Recently, various wide color gamut displays have been developed. Because of color gamut differences between wide gamut displays and the standard definitions, the color reproduction on such display system is not equal to original images. To overcome this, a color transformation such as gamut mapping algorithm is applied in conventional systems. But this manipulates only the video signal that would reduce the signal dynamic range and produces quantization error of video signal.In this paper, we propose a new optical Color Gamut Processing instead of an image data mapping. In the method, an individual color gamut of the standard definitions can be composed of an optical mixture of original primary colors. As a result, a perfect color match for the various standards can be realized within a display gamut without any signal artifacts.Moreover the same concept is applied to the video stream in order to elevate scene luminance. A scene-adaptive Dynamic Color Gamut Processing measures a color gamut for every video frame and adjusts a matched display color gamut so that it is able to increase display contrast in comparison to conventional display systems.     

A rugged display: Recent results of flexible cholesteric liquid‐crystal displays

Abstract— A 3‐m‐long rugged flexible display having a novel single‐plastic‐substrate structure has been demonstrated with a coated cholesteric liquid‐crystal mixture. The display is designed to be fabricated by a roll‐to‐roll process to increase productivity at a competitive cost. It has the advantage of having almost no limitation in display length. The high‐resolution (300‐dpi) monochrome cholesteric liquid‐crystal display (ChLCD) can be achieved by using a photo‐addressing method. A single‐layered 10.4‐in. color ChLCD also has been developed with good color and contrast.     

Full-color reflective display device using holographically fabricated polymer-dispersed liquid crystal (HPDLC)

Abstract— A method of controlling the color of a holographic polymer-dispersed liquid-crystal (HPDLC) reflective display device has been achieved. By merely controlling the optical setup during fabrication, without changing the materials or laser light source, three primary-color devices were fabricated. Since the color of the device can be controlled continuously, a large color-reproducible area on the chromaticity diagram can be obtained. The resulting device was adequately transparent at other wavelengths to enable multiple devices to be stacked to obtain a mixture of colors. There was no significant change in color when applying an electric field. The three devices had similar reflectances and electro-optical characteristics. Therefore, this device has good potential for full-color display applications.     

A laser current control algorithm to avoid color distortion in laser projection displays

Laser display technology has gradually become an important solution for large screen display. As a mature lighting technology in recent decades, phosphor has been widely used in the field of lighting and display. As a solid‐state light source, it has the advantages of low power consumption, environmental protection, rich color, and dynamic modulation. The luminescent efficiency of phosphors varies with temperature, which results in the nonlinearity of phosphor emission when the light source is dynamically modulated and the color temperature drift of the display image. In this paper, a control model of color temperature of laser TV display changing with laser current and temperature is established. The color temperature of laser TV is corrected by using current compensation control algorithm. The problem of color temperature drift caused by the change of phosphor conversion efficiency with t7emperature is solved. The color temperature deviation is 1118 K in the luminance range of the light source before compensation. By compensating and controlling the laser current, the ratio of blue light and phosphor is constant when the luminance changes, thus ensuring the color temperature constant when the luminance of the laser light source changes. The color temperature deviation is 50 K in the luminance range. By analyzing the different luminance of the display image, the stability of the color temperature is improved.     

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.     

Manipulation and presentation of multidimensional image data using the peano scan

A fractal curve first discussed by Giuseppe Peano has useful statistical properties in image processing. The curve can act as a transform between a line and n-dimensional space retaining some of the spatially associative properties of the space. Applications of the curve include multispectral image display, compression in the color and spa-tial domain, classification, and color display. The technique enables the display of high quality color images on a frame store capable of displaying only 256 colors simultaneously. A logically ordered and complete set of colors for false color work can be selected. An im-provement in compression by about 3X for color images can be ob-tained by using this method in conjunction with an existing spatial compression technique. A simple algorithm for constructing the curves is shown.     

New display concept for realistic reproduction of high-luminance colors

A new display concept for reproduction of high-luminance colors based on a liquid crystal display has been developed using a brighter backlight unit and color mapping algorithms. The new concept is able to display brighter colors close to a peak luminance of a display white than conventional displays so that realistic scene of brighter colors is better reproduced. It may also be one of the future display solutions needed to extend the color gamut in the direction of brighter colors, which is a principal limitation in conventional displays even in high-dynamic range display systems. With the new concept, an xvYCC- (extended-video YCbCr) compatible display can be easily realized.     

Usage of multisensory information in scientific data sensualization

Multisensory scientific data sensualization methods that utilize virtual reality technology permit the use of several human sensations, such as visual, acoustic, and tactile sensation to display numerical data. The purposes of multisensory data sensualization can be classified as follows: (a) representing the relationships between different kinds of data; (b) displaying data utilizing sensory integration; and (c) representing conditions using the compound image. By using multisensory information, computers increase the ability to express data. However, these methods lead us to the question of which sensation should be used to display data most effectively. In this study, a multisensory data sensualization environment was developed in which color, loudness, sound frequency, and air flow pressure could be used to display scientific data. In particular, a wind sensation display prototype using air flow pressure was developed to generate tactile sensation. A basic experiment was conducted on sensory interference when subjects used two kinds of sensations simultaneously. From these results, guidelines for the usage of multisensory information for each purpose is proposed.     

A first demonstration and analysis of the biprimary color system for reflective displays

A new biprimary color system is demonstrated for single‐layer reflective displays, capturing much of the improved color performance of multilayer displays while potentially maintaining single‐layer display advantages in high resolution and faster switching. Electrophoretic pixels were operated with dual‐particle complementary‐colored dispersions such as green/magenta (G/M). Using simple interdigitated three‐electrode architecture, four colored states (KWGM) were achieved with a preliminary contrast ratio of 10 : 1. Furthermore, biprimary ink dispersions were shown to be functional in a more advanced electrokinetic pixel structure. A full‐color biprimary pixel contains three complementary subpixels (G/M, B/Y, R/C), and the requisite electrophoretic ink dispersions were also formulated and spectrally characterized in this work. Lastly, theoretical color space mapping confirms that the biprimary concept provides twice the brightness and twice the color fraction compared with the conventional RGBW subpixel approach, and that the biprimary concept can approach performance close to that of magazine print (Specifications for Web‐Offset Print).     

Dynamic adaptation model and equal‐whiteness CCT curves for the choice of display reference white

Abstract— A dynamic adaptation model (DAM), based on the variations in the luminance levels under the same chromaticity viewing conditions and equal‐whiteness correlated‐color‐temperature (CCT) curves (EWCCs) derived by using the proposed DAM, is proposed. The proposed model was obtained by the transformation of the test colors for high luminance into the corresponding colors for low luminance. In the proposed model, the optimal coefficients are obtained from the corresponding color data from Breneman's experiments. From the experimental results, it was confirmed that the chromaticity errors between the predicted colors by the proposed model and the corresponding colors of Breneman's experiments are 0.004 in u′v′ chromaticity coordinates. The prediction performance of the proposed model is excellent because this error is the threshold value that distinguishes two adjacent color patches. Equal‐whiteness CCT curves (EWCs) are also proposed using the proposed DAM. By using the proposed EWCCs, an analysis of the difference between the selected video‐display‐unit reference‐white CCT values can be made. Additionally, the proposed EWCCs can be used as the theoretical standard which determines the reference white of the color video display units.     

Chromatic characterization of novel multicolor reflective display with electrochemically size‐controlled silver nanoparticles

Multifunctional electrochromic materials that enable control of multiple colors, color density, and specular reflection are potential candidates for novel reflective display devices. In this research, we focus on Ag nanoparticles that exhibit various optical states based on their localized surface plasmon resonance (LSPR). Because the LSPR band depends on the size and shape of the nanoparticles, control of the morphology of Ag nanoparticles can lead to dramatic changes in color. In order to apply this color variation for display devices, we investigate here the electrochemical formation of size‐controlled Ag nanoparticles using a voltage‐step method that consists of an application of two successive different voltages (V₁ and V₂). The electrochemically deposited Ag nanoparticles appear red and blue depending on the time for V₂ voltage application. The color changes between the transparent and colored states are reversible. Then, we successfully demonstrate the first LSPR‐based multicolor electrochromic device in which reversible control of five optical states—transparent, silver mirror, red, blue, and black—is possible.     

Power‐saving primary design for displays enclosing a target color gamut

Abstract— Display primaries are optimized for the trade‐off between the total primary power and color gamut under the requirement that a target color gamut is enclosed by the color gamut of the display. LED displays and HDTV color gamut are taken as examples. Compared to the display using a set of typical commercial RGB LEDs, it was found that a total optical (electrical) power of 23.6% (15.6%) can be saved for the display using optimal RGB LEDs. Although the size of the display color gamut is sacrificed, the color gamut of the display using optimal RGB LEDs still encloses the HDTV color gamut. The combined effect of the LED luminous efficiency and white‐point condition on the determination of the optimal LED wavelengths and bandwidths is also studied.     

Display text segmentation after learning best-fitted OCR binarization parameters

In this paper text segmentation in generic displays is proposed through learning the best binarization values for a commercial optical character recognition (OCR) system. The commercial OCR is briefly introduced as well as the parameters that affect the binarization for improving the classification scores. The purpose of this work is to provide the capability to automatically evaluate standard textual display information, so that tasks that involve visual user verification can be performed without human intervention. The problem to be solved is to recognize text characters that appear on the display, as well as the color of the characters’ foreground and background. The paper introduces how the thresholds are learnt through: (a) selecting lightness or hue component of a color input cell, (b) enhancing the bitmaps’ quality, and (c) calculating the segmentation threshold range for this cell. Then, starting from the threshold ranges learnt at each display cell, the best threshold for each cell is gotten. The input and output data sets for testing the algorithms proposed are described, as well as the analysis of the results obtained.     

Spatial gamut mapping algorithms for cross‐display color reproduction

Abstract— Owing to the fast developments of computer networks and color imaging technologies, there is a tendency towards remote proofing in the printing or textile industries. More cases such as cross‐display color matching will occur in the future information society. The problems of color mismatching we usually find in cross‐display devices have been widely discussed today. In this paper, to achieve equivalent color matching between a sRGB monitor and an Adobe RGB monitor, the spatial gamut mapping algorithm (SGMA), which introduces sigmoidal tone mapping, multi‐mapping paths, and unsharp mask (USM) operation into a sRGB color‐management system, is proposed. According to the designs of USM locations, this proposed SGMA can be further developed into pre‐USM, post‐USM, and double‐USM types. Besides, two critical image characteristics, edge map and color histogram, are investigated to establish the relationship between image content and SGMA. The psychophysical experimental results show that double‐USM SGMA obtains better color matching than the other spatial types.     

背投式多投影系统中各向异性问题的研究

目的 针对背投式多投影系统中存在的各向异性问题,提出一套行之有效的解决方案.方法 首先,为了解决以静态观众为主体的多投影系统各向异性问题,基于反馈机制提出了以特定位置为中心的“最佳观测域”,并在该区域内实现了真正的视觉无缝画面校正;然后,基于视觉人体跟踪技术进一步提出了以特定交互者为中心的“动态最佳观测域”框架,并结合模糊预测控制思想从人体重心检测、跟踪和投影仪亮度实时补偿等3个方面对该框架内的各个组成模块的关键技术进行了阐述.结果 实验结果显示,利用交互者运动的时空连续性优化后的动态最佳观测域算法,具有较好的鲁棒性和实时性.同时,与其他类似方法相比获得了更好的视觉无缝校正效果,其中观测距离为1 m、3 m和5 m时,对应的亮度样本标准差分别为17.11、13.17和9.2.结论 提出的各向异性解决方案,将实时反馈信号引入校正过程中,有效提高了输出画面质量.通过实验测试和性能评估,验证了文中方法的可行性.     

A fast‐switching OCB‐mode LCD for high‐quality display applications

Abstract— Optically compensated bend (OCB) mode is a promising technology, due to its wide range of viewing angles without gray‐scale inversion or color shift, fast response, high contrast ratio, and wide temperature range. This paper summarizes the fundamental characteristics of OCB mode and discusses the development of field‐sequential‐color displays and 3‐D displays for future high‐quality display applications.     

Active matrix field sequential color electrically suppressed helix ferroelectric liquid crystal for high resolution displays

In this article, we disclose a 3‐inch 250ppi active matrix field sequential color (FSC) display based on electrically suppressed ferroelectric liquid crystal (ESHFLC). ESHFLC's ultra‐fast response time (~10 μs at 6.67 V/μm) enables the display resolution to be tripled via FSC technique. The photo‐alignment technology provides ESHFLC with optimal anchoring energy that contributes to a high contrast ratio over 10 K:1 on single pixel level measurement. A specific 3T1C pixel circuit is designed to generate continuous gray scale from FLC binary switching by utilizing the pulse width modulation concept. The low temperature poly silicon thin‐film transistor array has been used to fabricate the FSC ESHFLC display panel. We achieved an 8‐bit gray level for each color subframe, that is, R, G, and B colors that results in 24‐bit color images. We believe, because of the good optical quality and cost‐effective fabrication, this display may replace in‐plane switching or fringe‐field switching in the near future for the portable device market. Moreover, high resolution FSC ESHFLCs can find applications in the emerging virtual reality displays.     

一种改进的高斯混合背景模型算法及仿真

高斯混合模型广泛应用于基于背景建模的运动目标检测中,高斯混合模型参数估计和更新算法影响到背景模型的性能.文中对传统的高斯混合背景模型进行了改进,针对背景局部运动、活动阴影等问题,采用混合色彩值抑制阴影,在背景更新中引入一个"前景支撑映射"(Foreground Support Map, FSB),较好地解决了背景模型的提取、更新、背景扰动、外界光照变化等问题.实验结果证明,实验结果验证了该方法的有效性和在复杂背景变化下的鲁棒性.     

A method for selecting display primaries to match a target color gamut

Abstract— A method for selecting primaries of a wide‐gamut display is proposed, in which display color gamut is designed to match a target color gamut in CIELAB color space. A standard deviation of the relative maximum chroma of display and target color gamuts is defined. The selection method optimizes display primaries for the minimum standard deviation so that display and target color gamuts are similar in shape. It is shown that the color gamut of a laser display designed by this method is similar in shape to the theoretical maximum, or optimal, color gamut of objects. It is also shown that the color gamut of an LED display can be designed to include 99.7% of the gamut of Pointer's real‐world surface colors. LED primaries are selected to minimize the standard deviation of the relative maximum chroma of effective display color gamut and a target color gamut which is defined to include Pointer's real‐world surface colors. For both the laser and LED displays, it is necessary to constrain the red‐primary wavelength to avoid excessive optical power for the red primary.     

基于AD590的嵌入式温度采集及显示系统

在本设计中采用了以AD590为核心,与单片机相辅相成,实现温度的数字化显示。本系统的主要功能是时一定范引内的温度进行循环采集、测量和显示。在这设计里采用了数字显示,电路能够比较精确的显示器温度值。除此之外,本设计中还采顶留了远距离异步通信接口,可以与远红外线传送技术相结合,以实现远距离温度控制的扩展功能。