Expanded Color Gamut Research Articles

Ultra-low-defect homoepitaxial micro-LEDs with enhanced efficiency and monochromaticity for high-PPI AR/MR displays

The issue of brightness in strong ambient light conditions is one of the critical obstacles restricting the application of augmented reality (AR) and mixed reality (MR). Gallium nitride (GaN)-based micro-LEDs, renowned for their exceptional brightness and stability, are considered the foremost contenders for AR applications. Nevertheless, conventional heteroepitaxial growth micro-LED devices confront formidable challenges, including substantial wavelength shifts and efficiency droop. In this paper, we firstly demonstrated the high-quality homoepitaxial GaN-on-GaN micro-LEDs micro-display, and thoroughly analyzed the possible benefits for free-standing GaN substrate from the material-level characterization to device optoelectronic properties and micro-display application compared with sapphire substrate. The GaN-on-GaN structure exhibits a superior crystal quality with ultra-low threading dislocation densities (TDDs) of ~ 105 cm−2, which is three orders of magnitude lower than that of GaN-on-Sapphire. Through an in-depth size-dependent optoelectronic analysis of blue/green emission GaN-on-GaN/ Sapphire micro-LEDs from 100 × 100 shrink to 3 × 3 μm2, real that a lower forward voltage and series resistance, a consistent emission wavelength (1.21 nm for blue and 4.79 nm for green @ 500 A/cm2), coupled with a notable reduction in efficiency droop ratios (15.6% for blue and 28.5% for green @ 500 A/cm2) and expanded color gamut (103.57% over Rec. 2020) within GaN-on-GaN 10 μm micro-LEDs. Last but not least, the GaN-on-GaN micro-display with 3000 pixels per inch (PPI) showcased enhanced display uniformity and higher luminance in comparison to its GaN-on-Sapphire counterpart, demonstrating significant potentials for high-brightness AR/MR applications under strong ambient light.

Multilayer all-dielectric metasurfaces expanding color gamut

Abstract Structural color, arising from the interaction between nanostructures and light, has experienced rapid development in recent years. However, high-order Mie resonances in dielectric materials often induce unnecessary sub-peaks, particularly at shorter wavelengths, reducing the vibrancy of colors. To address this, we have developed a multilayer dielectric metasurface based on silicon-rich silicon nitride (SRN), achieving expanded color gamut through precise refractive index matching and suppression of high-order resonances. This strategy introduces more design dimensions and can reduce the complexity of material deposition. It enables the generation of vibrant colors in a 3 × 3 array, with a resolution of approximately 25,400 dpi, demonstrating its potential applications in displays.

Enhancing the color gamut of waveguide displays for augmented reality head-mounted displays through spatially modulated diffraction grating

Augmented reality (AR) applications require displays with an extended color gamut to facilitate the presentation of increasingly immersive content. The waveguide (WG) display technology, which is typical AR demonstration method, is a critical constraint on the color gamut of AR systems because of the intrinsic properties of the holographic optical elements (HOEs) used in this technology. To overcome this limitation, we introduce a method of spatially modulated diffractive optics that can expand the color gamut of HOE-based WG displays. This approach involves spatial modulation using sub-pixelized HOEs, which enables the diffraction of red, green, and blue rays along identical directions. The proposed structure considers both the characteristics of the HOE and the wavelength sensitivity of the observer to optimize the color gamut. Consequently, an expanded color gamut was achieved. The results of the theoretical and experimental analyses substantiate the effectiveness and practicality of this method in enhancing the color gamut of HOE-based WG displays. Thus, the proposed method can facilitate the implementation of more immersive AR displays.

9‐2: TurboLED: Novel Pixel Design for Reduced Power Consumption and Expanded Color Gamut

We present a novel pixel design called TurboLED® for reducing the power consumption of displays, as well as extending lifetime and expanding color gamut. In a TurboLED® display, each pixel comprises stacked LEDs, with independent lighter and deeper red, green and blue emissive units. We demonstrate 36.9% power savings for a TurboLED® display compared to a standard RGB OLED display. With further optimization, there is potential to reduce display power consumption by up to 50% and enable the Rec. 2020 color gamut without significant increase in power consumption.

An Investigation of the Value of Wide Color Gamut in Motion Pictures

<italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">Thanks to the advancements in cinema and display technologies wider color gamuts are now possible. These technologies can support and reproduce highly saturated color content. Bear in mind, the ability to produce colors with an extremely high chroma component is strictly a capability of the technology and not a necessity that the image content must follow. In short, the decision to utilize the expanded gamut available in advanced cinema technologies is at the discretion of the creative forces behind the project. There are a number of different factors that can contribute to the creative color decisions made for motion pictures, with the primary factor being the esthetic nature of the content produced. Through creative-preference assessments of saturation adjustments in various image contents, the value of the expanded color gamut in motion picture mastering was assessed. Three images of comparable chroma histograms were utilized in the study to feature human skin tones, animated characters, and natural scenery, respectively. Upon being adjusted, each image was rendered with color content outside the boundaries of the Digital Cinema Initiatives (DCI)-P3 gamut. A two-alternative-forced-choice psychophysical study was conducted to estimate observer preference of the saturation levels in each image. From the observers’ selections, the reaction to the expanded image saturation in the three images was plotted and assessed for statistical significance. Through this study, it was found that there is a preference to incorporate colors exclusive to wider color gamuts that extend past the boundaries of International Telecommunication Union-Radiocommunication (ITU-R) Recommendation BT.709 and DCI-P3. It was also confirmed that the medium in which the content was generated influences the level of saturation preferred. Overall, this research provides a look into how technical capability and artistic vision can be connected</i> .

Demonstrating a multi-primary high dynamic range display system for vision experiments

We describe the design, construction, calibration, and characterization of a multi-primary high dynamic range (MPHDR) display system for use in vision research. The MPHDR display is the first system to our knowledge to allow for spatially controllable, high dynamic range stimulus generation using multiple primaries. We demonstrate the high luminance, high dynamic range, and wide color gamut output of the MPHDR display. During characterization, the MPHDR display achieved a maximum luminance of , a maximum contrast range of , and an expanded color gamut tailored to dedicated vision research tasks that spans beyond traditional sRGB displays. We discuss how the MPHDR display could be optimized for psychophysical experiments with photoreceptor isolating stimuli achieved through the method of silent substitution. We present an example case of a range of metameric pairs of melanopsin isolating stimuli across different luminance levels, from an available melanopsin contrast of 117% at to a melanopsin contrast of 23% at .

216 shades of gray: high bit-depth projection using light intensity control.

Projectors create grayscale images by outputting a series of bitplanes or binary images within a short time period. While this technique works well for projecting low bit-depth (8-bit) images, it becomes infeasible for high bit-depth (say, 16-bit) projection - a capability that is increasingly desirable in many applications including cinemas and gaming. Existing designs for high bit-depth projection rely on multiple spatial light modulators and, as a consequence, their costs and complexities are usually far beyond the average consumer. In this paper, we describe a technique for high bit-depth projection using a single light modulator by adopting intensity-modulated light sources. With the proposed light intensity modulation, we show that the number of bitplanes required to achieve a desired bit-depth can be dramatically reduced - by marginally trading-off the brightness of the projected image. Hence, given a spatial light modulator of a fixed bandwidth for projecting bitplanes, the proposed projector design can achieve higher bit-depth as well as expanded color gamut while achieving the same video framerate as conventional projectors. The proposed design involves a minor modification to traditional projector designs, namely intensity modulation of the light sources, and hence, can be adopted widely by both traditional low bit-depth projectors and modern high dynamic-range projectors. Finally, we present a hardware prototype to showcase and validate the performance of the proposed design.

Laser Digital Cinema Projector

The reason for wider color gamut of laser display systems rests on RGB laser lights whose color coordinates very approach the locus of gamut chart, which means the most saturated colors. A novel, practical and simplest method to reduce the laser speckle is developed. A laser digital cinema projector (LDCP) is manufactured for the first time in the world. The LDCP enjoys all benefits of 166% NTSC expanded color gamut, beyond 9 024 ANSI lumens light output, a minimum sequential contrast ratio of 2595:1, 2048 X 1080 display resolution, etc.

Beyond Red&amp;#x2013;Green&amp;#x2013;Blue (RGB): Spectrum-Based Color Imaging Technology

This article presents a comprehensive study on the spectrum-based color reproduction system, called Natural Vision (NV), which aims to break through the limitation of red&#x2013;green&#x2013;blue (RGB) three-primary schemes. After a basic discussion on the motivation for color imaging technology beyond RGB, the method for systematizing the multispectral and multiprimary color imaging technologies, including image capture, processing, storage, printing, and display, is presented. Then experimental multispectral systems for both still image and video are introduced, and the following features of spectrum-based scheme are revealed: a) highly accurate color reproduction is possible even under different illumination environment, b) an expanded color gamut can be reproduced by multiprimary color displays, c) the influence of observer metamerism can be reduced by the spectral color reproduction, and d) the quantitative spectral attributes of an object, useful for its analysis or recognition, can be captured and preserved. Finally, the effectiveness of the system is also demonstrated through experiments in fields of application, such as medicine, digital archives, color printing, electronic commerce, and computer graphics.

NexPress Glosser Process for Photo-Rich Applications

In order to broaden up the type of substrates that can be used for high gloss photo-rich applications, a process combining the intelligent applications of clear dry ink to images printed from the NexPress 2100 digital press to a near-line Glosser unit is used. With the correct combination of clear dry ink and glossing conditions of the belt Glosser, a large variety of substrates are shown to achieve expanded color gamut, high and uniform gloss at the same time. The glossing/finishing process relating to the belt glosser both in the simplex and duplex modes will be discussed.

Enabling Expanded Color Gamut and In-line Coating Processes

Most four-color printing processes that are extensively used in electrophotographic (EP) applications today are based on the SWOP (Specifications for Web Offset Publications) colorants. Although, this set of colorants offers many advantages, it fails in many aspects as it does not deliver many often requested colors in digital printing. For example, most corporate identity colors cannot be faithfully reproduced with the available gamut possible with this color set. Most attempts to increase the color gamut by selecting high chroma colorants only provides marginal improvements. At the same time these colorants can have high impact on toner performance developer life. Many of the limitation of a four color system can be addressed by a adding fifth module in the digital color press. One such digital press now commercially available, is NexPress 2100. By proper selection of fifth color DryInk&#x2122; or toner, and utilizing pentachrome process, Nexpress 2100 digital press manages to expand color gamut on demand while still continuing to utilize the standard CYMK toners. The result is a low cost solution to matching most colors that are often demanded by customers. With the availability of fifth module, it is also possible to use it to apply a clear overcoat in an intelligent manner. Such a coating process is truly inline and offers efficient workflow solutions. Clear Overcoats provides superior protection and enhance many image quality attributes. Many capabilities and limitations of fifth module will be presented. Impact on EP process and color gamut by the colorant selection will also be discussed.

Color Conversion Method for Multiprimary Display Using Matrix Switching

The range of reproducible color, i.e., color gamut, of conventional three-primary display devices is sometimes insufficient for reproducing the natural color of an object through color imaging systems. A multiprimary display is being developed for the purpose of reproducing an expanded color gamut using more than three primary colors. In this paper, a color conversion method is proposed to reproduce the natural color by additive mixture of multiprimary colors. The multiprimary color signal in this conversion method is calculated from the three-dimensional color coordinates CIE-XYZ, considering the dynamic range of each primary color. Divided into some linear elements from the polyhedral color solid of the multiprimary display, the conversion considering the constraint of the dynamic range can be performed by simple calculation without iterative calculation or a huge three-dimensional look up table. A fast computation method with a two-dimensional look-up-table is also presented. Using the proposed method, the result of the color reproduction is experimentally demonstrated by a six-primary projection display.

Reflection and transmission of polymer liquid‐crystal coatings and their application to decorative arts and stained glass

AbstractPolymer liquid crystals produce color by light interference from their molecular layers. The colors show additive properties, are highly saturated, have an expanded color gamut, and change with angle of viewing. They produce more stable and durable coatings than most other liquid crystals and they adhere well to the substrate. Experimental work was carried out confirming the above properties. It has been also demonstrated that the spectral reflectance of colored substrates can be modified by coating them with polymer liquid crystals. In addition to painting and sculpture they are also of interest in a wide variety of decorative uses and in light transmission applications such as in stained glass. Examples using these materials are shown and discussed.