Perceptually‐based Color Assignment

Color assignment is a complex task of incorporating and balancing area configuration, color harmony, and user's intent. In this paper, we present a novel method for automatic color assignment based on theories of color perception. We define color assignment as an optimization problem with respect to the color relationships as well as the spatial configuration of input segments. We also suggest possible constraints that are suitable for task‐specific purposes and for enhancing visual appeal. Our colorization scheme is useful in many applications such as infographics, computer‐aided design, and visual presentation. The user study shows that our method generates perceptually pleasing results over a variety of data sets.     

Hue rotation (HR) and hue blending (HB): Real‐time image enhancement methods for digital component video signals to support red‐green color‐defective observers

The mutual understanding of color‐normal observers (CNOs) and color‐defective observers (CDOs) is now essential because personal color information display environments have been widely adopted. However, existing tools for CDOs offer only color discrimination; they fail to support color impression (ie, saturation and contrast). Therefore, we need a novel tool that offers help in distinguishing opponent colors, while preserving color saturation. We introduce two key techniques for realizing this difficult goal. The former is the repeated sequential display of the original and processed images to support the formation of unified correct percepts that provide discrimination of both red‐green and yellow‐blue opponent colors. One image, ie, original, exhibits correct yellow‐blue but distorted red‐green information for CDOs while the other, ie, processed, provides synthesized distinguishable red‐green but confusable yellow‐blue information for CDOs; here, hue rotation (HR) is useful for advanced users whereas hue blending (HB) is suitable for general. The latter is realized by the real‐time video processing available on smartphones; our algorithms support direct processing of the digital component video signal formats (eg, Y, C_R, and C_B). Subjective tests suggest that the two above‐mentioned algorithms will, along with embedding a lightweight real‐time dichromatic simulation facility for CNOs, greatly help the mutual understanding of CNOs and CDOs.     

Full‐color AMOLED with RGBW pixel pattern

Abstract— A full‐color AMOLED display with an RGBW color filter pattern has been fabricated. Displays with this format require about one‐half the power of analogous RGB displays. RGBW and RGB 2.16‐in.‐diagonal displays with average power consumptions of 180 and 340 mW, respectively, were characterized for a set of standard digital still camera images at a luminance of 100 cd/m². In both cases, a white‐emitting AMOLED was used as the light source, and standard LCD filters were used to provide the R, G, and B emission. The color gamuts of these displays were identical and the higher overall efficiency of the RGBW format results from two factors. First, a large fraction of a typical image is near neutral in color and can be reproduced using the white sub‐pixel. Second, the white sub‐pixel in an RGBW AMOLED display is highly efficient because of the absence of any color filter. The efficiency of these displays can be further enhanced by choosing a white emitter optimized to the target display white point (in this case D65). A two‐emission layer configuration based upon separate yellow and blue‐emitting regions is shown to be well suited for both the RGBW and RGB formats.     

White LEDs using the sharp β‐sialon: Eu phosphor and Mn‐doped red phosphor for wide‐color gamut display applications

The sharp β‐sialon (Si_6‐zAl_zO_zN_8‐z : 0 < z < 0.1):Eu green phosphor, combining with a blue LED and CaAlSiN₃:Eu red phosphor, is suitable for the wide‐color gamut white LEDs backlighting system, because of its sharp and asymmetric emission spectrum shape. However, the color gamut and the brightness of the aforementioned display is restricted because of the wide emission band of the CaAlSiN₃:Eu red phosphor. In this work, we used K₂SiF₆:Mn as an alternate red phosphor, which has a sharp emission spectrum. The display with the white LED using sharp β‐sialon:Eu and K₂SiF₆:Mn shows a wide‐color gamut, which covers the hole NTSC triangle. The use of K₂SiF₆:Mn enables to realize not only a wider color gamut but also a higher brightness of displays, compared with the use of CaAlSiN₃:Eu. Furthermore, it is confirmed that the white LED using sharp β‐sialon:Eu and K₂SiF₆:Mn is stable against temperature and also durable under the accelerated drive conditions.     

An LCOS‐based digital‐cinema projector

Abstract— A digital cinema projector that utilizes three JVC QXGALCDs, and provides 12,000 lumens, 2000:1 contrast, and 3‐Mpixel resolution was developed. This system, which was described in a prior paper (see Ref. 10), has a novel optical configuration based on the use of intermediate imaging optics and wire‐grid polarizers and is described in greater detail in this paper. The polarization optics, including the polarization compensators, contribute to a system that provides high contrast at a low f/#, with a wide color gamut and minimal color shading at high power.     

DIA‐PDP with high luminous efficacy and increased vertical resolution

Abstract— A PDP utilizing a new cell configuration to improve the vertical resolution and luminous efficacy is proposed. In this configuration, a delta subpixel arrangement is adopted because it reduces the vertical pixel pitch by half and increases the vertical resolution. In this configuration, R, G, B subpixels form triangles which are diamond shaped, the rational for calling this technology “DIAPDP.” High luminous efficacy is achieved by reducing the reflectivity of the panel. The lower reflectivity enables increased transmittivity of the light‐reduction filter which is part of the PDP panel, thus ensuing sufficient contrast under bright conditions. The higher transmittivity increases the luminous efficacy with the filter. Results obtained for a 46‐in. panel demonstrate a 33% increase in the luminous efficacy when using the filter. The DIA cell configuration is further modified to be a “clustered DIA” in order to improve the color mixing. Through subjective evaluation, the color mixing was compared with that of panels based on a trio subpixel arrangement and DIA, and the effect on color mixing was confirmed. The luminous efficacy of clustered DIA is also shown to be equal to that of DIA.     

Performance evaluation of multi‐primary color‐matrix layouts for mobile displays

Abstract— Different subpixel layouts for multi‐primary displays will be presented and their spatial performance analyzed. The layouts studied include red, green, blue, yellow, and cyan subpixels, arranged in 5/5, 5/4, and 5/3 configurations. In the 5/5 configuration, five primaries are arranged on five subpixels forming a square pixel. In the 5/4 configuration, five primaries are arranged on two square units, each of which have four subpixels so that the cyan and yellow subpixels are missing in alternate pixels. In the 5/3 layout, the multi‐primary color matrix is placed on top of a standard RGB TFT backplane with a subpixel aspect ratio of 1:3, resulting in an increased period of the full color sequence. Different data‐rendering methods for the modified color sequences were studied and their implication on the spatial performance were analyzed, given in terms of reproduction accuracy, i.e., the average S‐CIELAB error between data reproduced on a reference display and that reproduced on the examined layout. The reproduction error as a function of the angular substance of a pixel is reported for different layouts and rendering methods and are compared to that of an RGB display. It will be shown that the modified multi‐primary layouts reduce power consumption and provide good image quality for mobile applications.     

A full‐color eyewear display using planar waveguides with reflection volume holograms

Abstract— A full‐color eyewear display with over 85% see‐through transmittance with a 16° horizontal field of view was developed. Very low color crosstalk, less than 0.008 Δu′v′ uniformity, and 120% NTSC color gamut were achieved. Waveguides with two in‐ and out‐coupling reflection volume hologram elements enabled a simple configuration that has an optical engine beside the user's temples. The reflection volume hologram elements used on the waveguides realized a small thickness of 1.4 mm for each waveguide, and an out‐coupling reflection volume hologram used as an optical combiner contributed a high see‐through transmittance of 85% due to its wavelength selectivity. However, there are technical challenges in achieving a reasonable screen size and quality color images with optics that utilize holographic waveguides because holograms have large chromatic dispersions compared to conventional optical elements such as lenses and mirrors. Approaches to overcome these issues are described.     

Properties and cathodoluminescence of Y2O2S:Eu thin films

Abstract— Europium‐activated yttrium oxysulfide thin films were fabricated by electron‐beam deposition of Y₂O₂S:Eu with consequent annealing in an H₂S/Ar gas mixture. Transformations in film composition and surface morphology as well as corresponding changes in the optical, photoluminescent, and cathodoluminescent properties were studied and will be discussed. It is shown that 248‐nm laser irradiation of heat‐treated films improves cathodoluminescence by as much as 30%, supposedly due to annealing. The developed phosphor films have a luminance comparable to that of annealed europium‐activated yttrium oxide films and improved color properties (CIE color coordinates: x = 0.624, y = 0.329), and are suitable for display and optoelectronics applications.     

Novel photo‐aligned LC‐polymer compensation film for wide‐view TN displays

Abstract— We demonstrate a novel TN‐display compensation film with excellent contrast and minimal color shift, meeting the requirements for avionics displays. The film configuration was identified via extensive computer modeling. The experimental implementation based on ROLIC's LPP/LCP (linearly photopolymerizable polymer/liquid‐crystal polymer) technology results in excellent agreement with theoretical predictions.     

Electron‐beam curing of color filters for flexible‐display applications

Abstract— Color filters spin‐coated on plastic and glass substrates have been cured by electron‐beam radiation instead of by the conventional thermal‐heating method. The electron‐beam curing of the color filters has many advantages over the thermal curing method. Electron‐beam curing is, in principle, a non‐thermal method where low‐temperature (<100°C) curing of color filters on plastic substrates can be realized for the manufacturing process of flexible display panels. A color‐filter resist having a 1.5‐μm thickness was spin‐coated on plastic (polycarbonate) and glass (corning 1737) substrates. The effect of the electron‐beam radiation conditions, such as electron‐beam energy (0.3–1.0 keV), radiation dosage (10–200 kGy), and ambient oxygen has been characterized. The degree of curing was analyzed by using the characteristic absorption peaks at 808 and 1405 cm^?1 in the FT‐IR spectrum. These two peaks originate from the carbon double bonds (>C=C<) of the multi‐functional acrylate monomer which exist in the color‐filter resist. By electron‐beam radiation, the spin‐coated color filter can be effectively polymerized at g (glass transition temperature) of the plastic substrates. The electron beam can solve the problems of the conventional thermal curing method, such as thermal deformation of a plastic substrate and difficulty in achieving dimensional control of a color‐filter pattern due to a large coefficient of thermal expansion (20–70 ppm/°C) compared to that of a glass substrate.     

Flexible color LCD panel driven by low‐voltage‐operation organic TFT

Abstract— A flexible color LCD panel driven by organic TFTs (OTFTs) was successfully demonstrated. A pentacene OTFT with an anodized Ta₂O₅ gate insulator, which can be operated at low voltage, was developed. In order to improve the electrical performance of the OTFT, the gate insulator was surface treated by processes such as O₂ plasma, UV light irradiation, and hexamethyldisilane treatments. The fabricated OTFT exhibited a mobility of 0.3 cm²/V‐sec and a current on/off ratio of 10⁷ with a low operating drain voltage of ?5 V. A fast‐response‐time flexible ferroelectric LCD, which contains polymer networks and walls, was integrated with the OTFTs by using a lamination and a printing technique. As a result, color images were achieved on the fabricated panel by using a field‐sequential‐color method at a low driving voltage of less than 15 V_pp.     

A novel local search algorithm with configuration checking and scoring mechanism for the set k‐covering problem

The set k‐covering problem, an extension of the classical set covering problem, is an important NP‐hard combinatorial optimization problem with extensive applications, including computational biology and wireless network. The aim of this paper is to design a new local search algorithm to solve this problem. First, to overcome the cycling problem in local search, the set k‐covering configuration checking (SKCC) strategy is proposed. Second, we use the cost scheme of elements to define the scoring mechanism so that our algorithm can find different possible good‐quality solutions. Having combined the SKCC strategy with the scoring mechanism, a subset selection strategy is designed to decide which subset should be selected as a candidate solution component. After that, a novel local search framework, as we call DLL_ccsm (diversion local search based on configuration checking and scoring mechanism), is proposed. DLL_ccsm is evaluated against two state‐of‐the‐art algorithms. The experimental results show that DLL_ccsm performs better than its competitors in terms of solution quality in most classical instances.     

Fabrication of 5.8‐in. OTFT‐driven flexible color AMOLED display using dual protection scheme for organic semiconductor patterning

Abstract— A 5.8‐in. wide‐QQVGA flexible color active‐matrix organic light‐emitting‐diode (AMOLED) display consisting of organic thin‐film transistors (OTFTs) and phosphorescent OLEDs was fabricated on a plastic film. To reduce the operating voltage of the OTFTs, Ta₂O₅ with a high dielectric constant was employed as a gate insulator. Pentacene was used for the semiconductor layer of the OTFTs. This layer was patterned by photolithography and dry‐etched using a dual protection layer of poly p‐xylylene and SiO₂ film. Uniform transistor performance was achieved in the OTFT backplane with QQVGA pixels. The RGB emission layers of the pixels were formed by vacuum deposition of phosphorescent small molecules. The resulting display could clearly show color moving images even when it was bent and operated at a low driving voltage (below 15 V).     

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.     

Broadband gap‐coupled half‐hexagonal microstrip antenna fed by microstrip‐line resonator

Half‐hexagonal microstrip antenna (H‐HMSA) is a compact version of HMSA, as it resonates at the same fundamental mode frequency. In this article, a compact configuration of a single layer, broadband gap‐coupled H‐HMSA has been proposed. Gap‐coupled H‐HMSA is fed indirectly by a λ/2 microstrip‐line resonator. Broad bandwidth (BW) is achieved with an effective use of resonance introduced by λ/2 resonator and gap‐coupled half‐hexagonal radiating patches. A peak gain of 7.07 dBi and measured BW (S₁₁ ≤ ?10 dB) of 11.5% at the center frequency of 5.2 GHz have been achieved, which occupies a small volume of 0.023 λ₀³ including the ground plane. The radiation patterns remain in the broadside direction throughout the return loss BW. Simulated results of the proposed antenna configuration are experimentally validated with good agreement.     

A compact proximity‐fed 2.4 GHz monostatic antenna with wide‐band SIC characteristics for in‐band full duplex applications

This article presents a dual polarized, proximity‐fed monostatic patch antenna (single radiator for both transmit and receive modes) with improved interport isolation for 2.4 GHz in‐band full duplex (IBFD) applications. The proximity‐fed radiating patch offers comparatively wider impedance bandwidth for presented design. Very nice self‐interference cancelation (SIC) levels for intended impedance bandwidth have been achieved through differential receive (R_x) mode configuration. The differential R_x mode based on 180° ring hybrid coupler acts as a signal inversion mechanism for effective suppression or cancelation of in‐band self‐interference (SI) that is, the leakage from transmit port. The implemented prototype of proposed antenna achieves ≥87 dB peak isolation for dual polarized IBFD operation. Moreover, the recorded interport isolation for validation model ≥60 dB within 10 dB‐return loss bandwidth of 90 MHz (2.36‐2.45 GHz). The measured radiation characteristics of implemented antenna demonstrate nice gain and low cross‐polarization levels for both transmit (T_x) and receive (R_x) modes. The dimensions of implemented antenna are 70 × 75 × 4.8 mm³. The novelty of this work is wide‐band SIC performance for monostatic antenna configuration with compact structure of presented design.     

Effects of Color,Scouring Method,and Age on the Visual Sensibility of Naturally Colored Organic Cotton (NaCOC)

In parallel to the social trend of green consumerism and well‐being, the demand for naturally colored organic cotton (NaCOC) continually increases in the textile and clothing industry. The present study examined the effects of NaCOC color, scouring method, and age on the visual sensibility of NaCOC. Two age groups (20s and 30s; 40s and 50s) of women rated three color sets of NaCOC specimens (ivory, green, and coyote brown) treated by two chemical scouring methods (Na₂CO₃ and NaOH) and two bioscouring methods (enzyme and boiling water) using 7‐point scales of nine visual sensibilities (bright‐dark; clear‐murky; heavy‐light; vivid‐subdued; warm‐cool; fresh‐stale; strong‐weak; showy‐plain; and luxurious‐cheap). Preferred scouring methods by NaCOC color and/or age group were recommended for each visual sensibility (e.g., preferred scouring methods for fresh sensibility are Na₂CO₃ for ivory NaCOC, Na₂CO₃ and NaOH for green NaCOC, and boiling water for coyote brown NaCOC). In addition, the representative visual sensibilities of each NaCOC color (e.g., those of coyote brown NaCOC are dark, murky, heavy, vivid, warm, stale, strong, plain, and luxurious sensibilities) were identified for the women participants. Last, it was demonstrated that a bioscouring method can replace the traditional chemical methods for selected visual sensibilities (e.g., boiling water for luxurious sensibility). © 2012 Wiley Periodicals, Inc.     

Inorganic EL devices with high‐performance blue phosphor and application to 34‐in. flat‐panel televisions

Abstract— A high‐performance inorganic electroluminescence (EL) device has been successfully developed by using an EL structure with a thick dielectric layer (TDEL) and sputtered BaAl₂S₄:Eu blue phosphor. The luminance and efficacy were higher than 2300 cd/m² and 2.5 lm/W at L⁶⁰, 120 Hz, respectively. Furthermore, the luminance at L⁶⁰, 1.2 kHz was more than 23,000 cd/m². The phosphor layer has a single‐phase and a highly oriented crystalline structure. The phosphor also shows high stability in air. A 34‐in. high‐definition television (HDTV) has been developed by combining a TDEL structure and color‐conversion materials. The panels with an optimized color filter demonstrated a peak luminance of 350 cd/m², a color gamut of more than 100% NTSC, and a wide viewing angle similar to that of plasma‐display panels. The high reproducibility of the 34‐in. panels using our pilot line has been confirmed.     

Flexible active‐matrix OLED displays: Challenges and progress

Abstract— Organic light‐emitting‐device (OLED) devices are very promising candidates for flexible‐display applications because of their organic thin‐film configuration and excellent optical and video performance. Recent progress of flexible‐OLED technologies for high‐performance full‐color active‐matrix OLED (AMOLED) displays will be presented and future challenges will be discussed. Specific focus is placed on technology components, including high‐efficiency phosphorescent OLED technology, substrates and backplanes for flexible displays, transparent compound cathode technology, conformal packaging, and the flexibility testing of these devices. Finally, the latest prototype in collaboration with LG. Phillips LCD, a flexible 4‐in. QVGA full‐color AMOLED built on amorphous‐silicon backplane, will be described.