Color Filter Research Articles

P‐212: Novel Stacked OLED and Pixel Design for Enhanced Lifetimes and Improved PPI

In this paper, we proposed a novel stacked OLED device, which consists of a single layer of RGB units stacked vertically together. In the stacked OLED display, the pixel aperture ratio is about triple of traditional displays. The color gamut with DCI‐P3 (CIE1931) of the stacked device reaches 99% without color filter. In addition, we explored a pixel circuit suitable for the device, which theoretically improves the lifetime of the device by about 300% in this drive mode.

P‐151: The Optimization of Quantum‐Dots Color Filter for Flexible Display Applications

This paper introduces a flexible and uniformly‐dispersed quantum dot (QD) color filter (QDCF) fabricated for micro‐LED by photolithography. We studied the condition of PET films and concentration of QDs, the optimized QDCF exhibited high quantum yield (QY) up to over 70%, and a high optical density (OD) over 1.2. The QY increased and then decreased with the increase of the concentration.

Deep-learning-assisted inverse design of polarization-multiplexed structural color filters with ultrahigh saturation based on all-dielectric metasurface

Although great progress has been made for metasurface-based structural color filters, there are still significant challenges in encoding metasurfaces with complex color images, especially in high saturation or multi-channel cases, where traditional iterative optimization calculations demand substantial computational resources. Here, we proposed a dual-channel multilayered all-dielectric metasurface that can generate structural colors accounting for 224% Standard RGB space, 168% Adobe RGB space and 78% of the 1931 CIE chromaticity space under vertically-polarized incidence. A deep learning-based designing approach is introduced to significantly reduce the computing consumption while maintaining high accuracy. Numerical simulations further demonstrated that the proposed design method is effective for encoding both complementary and independent images with high saturation and wide color gamut. Therefore, the proposed color filters may find potential applications in image display, information encryption and optical anti-counterfeiting.

90‐4: Field Sequential Color Micro‐LCD Enabling High‐resolution Light Field Displays

We report a light field display using a field sequential color (FSC) LCD based on mini‐LEDs. A newly designed panel with fast response triples the resolution by removing color filters. The color breakup is addressed by a deep learning‐based real‐time 3‐field driving method. Also, an elemental image rendering algorithm with extremely light computations is proposed.

36‐1: Invited Paper: Submicron Narrow‐Band Phosphors in Luminescent Color Filters & Next Generation MiniLED and MicroLED Displays

Both phosphors and quantum dots are currently used in liquid crystal displays (LCDs), with GE's KSF narrow red phosphor demonstrating the best possible red color point, reliability, and efficiency. Next generation miniLED and microLED based displays require excellent color quality (gamut) and high brightness which will require color conversion materials with high EQE and narrow emission peaks. Here we describe recent advancements in submicron narrow‐band phosphors which are being implemented in next‐generation miniLED displays, and being considered for enabling full‐color microLED and luminescent color filter displays of the future due to their excellent optical performance and robust nature.

Freeform metasurface color router for deep submicron pixel image sensors.

Advances in imaging technologies have led to a high demand for ultracompact, high-resolution image sensors. However, color filter-based image sensors, now miniaturized to deep submicron pixel sizes, face challenges such as low signal-to-noise ratio due to fewer photons per pixel and inherent efficiency limitations from color filter arrays. Here, we demonstrate a freeform metasurface color router that achieves ultracompact pixel sizes while overcoming the efficiency limitations of conventional architectures by splitting and focusing visible light instead of filtering. This development is enabled by a fully differentiable topology optimization framework to maximize the use of the design space while ensuring fabrication feasibility and robustness to fabrication errors. The metasurface can distribute an average of 85% of incident visible light according to the Bayer pattern with a pixel size of 0.6 μm. The device and design methodology enable the compact, high-sensitivity, and high-resolution image sensors for various modern technologies and pave the way for the advanced photonic device design.

Cu/Zn phthalocyanine dyes with up to 40% solubility in propylene glycol monomethyl ether acetate (PGMEA) for color filters

Color filters play an important role in the quality of complementary metal–oxide–semiconductors and thin-film-transistor liquid-crystal displays. Although pigment nanoparticles have traditionally been used as color filter colorants, the use of molecular dyes for preparing high-quality color filters is an emerging strategy. However, few studies have investigated the relation between the structure of dyes and their color filter characteristics, such as solubility, and thermal stability and photostability. In this study, six phthalocyanine dyes with different branched substituents and central metals (zinc and copper) were developed. These dyes displayed high levels of solubility in propylene glycol monomethyl ether acetate (up to 40.8 wt%), high light transmission, and satisfactory thermal stability and photostability, indicating their potential application in color filters. They may provide a way to explore more molecular dyes for color filters with excellent dissolution properties.

Novel Yellow Aromatic Imine Derivative Incorporating Oxazolone Moiety for Color Resist Applications

A novel aromatic imine derivative, 2′-(1,4-phenylene)bis[4-[(4-methoxyphenyl)methylene]-5(4H)-oxazolone] (PBMBO), was designed and synthesized as a yellow colorant additive for green color filters used in image sensors. The optical and thermal properties of the newly developed material were evaluated both in solution and within color filter film conditions. PBMBO demonstrated a molar extinction coefficient of 2.24 × 104 L/mol·cm in solution, surpassing that of the commercially employed yellow colorant MBIQO by a factor of 1.82. Color resist (CR) films incorporating PBMBO exhibited outstanding optical characteristics, displaying 0.03% transmittance at 435 nm, 99.3% transmittance at 530 nm, and a sharp slope within the 400 to 550 nm range. The decomposition temperature of PBMBO was 303 °C, indicating relatively superior thermal stability compared to MBIQO. Consequently, PBMBO emerges as a highly promising candidate for a yellow colorant additive in imaging sensor color filters, owing to its exceptional optical and thermal stability. Its potential applications are anticipated to extend across various fields of organic semiconductors.

Development of Augmented Reality Vision for Osteosynthesis Using a 3D Camera.

We developed a 3D camera system to track motion in a surgical field. This system has the potential to introduce augmented reality (AR) systems non-invasively, eliminating the need for the invasive AR markers conventionally required. The present study was performed to verify the real-time tracking accuracy of this system, assess the feasibility of integrating this system into the surgical workflow, and establish its potential to enhance the accuracy and efficiency of orthopedic procedures. To evaluate the accuracy of AR technology using a 3D camera, a forearm bone model was created. The forearm model was depicted using a 3D camera, and its accuracy was verified in terms of the positional relationship with a 3D bone model created from previously imaged CT data. Images of the surgical field (capturing the actual forearm) were taken and saved in nine poses by rotating the forearm from pronation to supination. The alignment of the reference points was computed at the three points of CT versus the three points of the 3D camera, yielding a 3D rotation matrix representing the positional relationship. In the original system, a stereo vision-based 3D camera, with a depth image resolution of 1280×720 pixels, 30 frames per second, and a lens field of view of 64 specifications, with a baseline of 3 cm, capable of optimally acquiring real-time 3D data at a distance of 40-60 cm from the subject was used. In the modified system, the following modifications were made to improve tracking performance: (1) color filter processing was changed from HSV to RGB, (2) positional detection accuracy was modified with supporting marker sizes of 8 mm in diameter, and (3) the detection of marker positions was stabilized by calculating the marker position for each frame. Tracking accuracy was examined with the original system and modified system for the following parameters: differences in the rotation matrix, maximum and minimum inter-reference point errors between CT-based and camera-based 3D data, and the average error for the three reference points. In the original system, the average difference in rotation matrices was 5.51±2.68 mm. Average minimum and maximum errors were 1.10±0.61 and 15.53±12.51 mm, respectively. The average error of reference points was 6.26±4.49 mm. In the modified system, the average difference in rotation matrices was 4.22±1.73 mm. Average minimum and maximum errors were 0.79±0.49 and 1.94±0.87 mm, respectively. The average error of reference points was 1.41±0.58 mm. In the original system, once tracking failed, it was difficult to recover tracking accuracy. This resulted in a large maximum error in supination positions. These issues were resolved by the modified system. Significant improvements were achieved in maximum errors and average errors using the modified system (P<0.05). AR technology using a 3D camera was developed. This system allows direct comparisons of 3D data from preoperative CT scans with 3D data acquired from the surgical field using a 3D camera. This method has the advantage of introducing AR into the surgical field without invasive markers.

Ultrathin Freestanding Nanocellulose Film Prepared from TEMPO-Mediated Oxidation and Homogenized Hydrogel.

This paper presents a versatile method to fabricate ultrathin nanofibrillated cellulose (NFC) films as thin as 800 nm by blade coating, which is compatible with a roll-to-roll process on a large scale. Our approach allows obtaining a dried nanocellulose film within a span of 1 h subsequent to 2,2,6,6-tetramethylpiperidine-1-oxyl radical-assisted oxidation and homogenization procedures. One of the thinnest freestanding NFC films with a thickness of 800 nm is achieved using a blade coating of nanocellulose after 72 h of oxidation followed by homogenization with a channel size of 65 μm. Incorporating water-soluble CdTe core-type quantum dots into the nanocellulose film led to a uniform emission under 385 nm UV irradiation, indicating excellent material compatibility. We anticipate nanocellulose developed in our study to be beneficial in biomimicry flying objects, environmentally friendly encapsulation, color filters, and energy storage device membranes, to name a few.

Leveraging statistical-spectral correlations of random metasurfaces for steganography and multi-wavelength cryptography

The ability to tailor the spectral response of photonic devices is paramount to the advancement of a broad range of applications. The vast design space offered by disordered optical media provides enhanced functionality for spectral tailoring while also making it challenging to map the spectral properties of such complex systems to their structural attributes. In this work, we investigate correlations between the configuration statistics of random metasurfaces and their spectral transmissivity in the visible, and leverage those to develop a reduced phase space. In the latter part of the manuscript, we use this reduced phase space to design a pixelated color filter that hides visual data within a preselected cover image for steganography. Furthermore, we design a pair of color filters that can collectively encrypt a given grayscale image in their spectral transmissivities. We envision such devices to create opportunities for the development of compact, next-generation cryptographic systems. More broadly, the results presented in this manuscript provide new, to the best of our knowledge, avenues for optimizing large-scale random metasurfaces to achieve enhanced optical functionalities for a wide variety of applications.

Logical Platforms for Mobile Application in Decision Support Systems Based on Color Information Processing

Logical Platforms for Mobile Application in Decision Support Systems Based on Color Information Processing

Forgered Image Perception System using CNN Algorithms

The progression and diversification of methodologies in digital image forensics and manipulation detection are evident in existing work, presenting innovative techniques tailored to specific aspects of forgery detection. These methodologies encompass various challenges such as copy-move forgery, manipulation detection, demosaicing artifacts, image splicing, edge detection, and compression analysis. Together, these studies exemplify ongoing efforts to enhance the accuracy, efficiency, and reliability of forgery detection methods within the constantly evolving landscape of digital image manipulation. The proposed image forgery detection system represents a pioneering advancement, surpassing the limitations of conventional methodologies. It integrates a comprehensive array of detection techniques, including copy-move analysis, color filter array scrutiny, noise variance inconsistency detection, and double JPEG artifact identification. These techniques are bolstered by Convolutional Neural Networks (CNNs). This innovative fusion not only addresses the limitations inherent in existing systems but also signifies a significant leap forward in functionality and efficacy. By synergistically leveraging the strengths of each detection method within a CNN framework, our approach promises heightened accuracy, robustness, and adaptability in discerning even the most sophisticated forms of image tampering. Keywords— Image Tampering, Double JPEG Compression, Demosaicing Artifacts, Recursive Edge Detection, Copy-Move Forgery Detection.

Simple Sol-Gel Protein Stabilization toward Rainbow and White Lighting Devices.

Fluorescent proteins (FPs) are heralded as a paradigm of sustainable materials for photonics/optoelectronics. However, their stabilization under non-physiological environments and/or harsh operation conditions is the major challenge. Among the FP-stabilization methods, classical sol-gel is the most effective, but less versatile, as most of the proteins/enzymes are easily degraded due to the need of multi-step processes, surfactants, and mixed water/organic solvents in extreme pH. Herein, sol-gel chemistry with archetypal FPs (mGreenLantern; mCherry) is revisited, simplifying the method by one-pot, surfactant-free, and aqueous media (phosphate buffer saline pH=7.4). The synthesis mechanism involves the direct reaction of the carboxylic groups at the FP surface with the silica precursor, generating a positively charged FP intermediate that acts as a seed for the formation of size-controlled mesoporous FP@SiO2 nanoparticles. Green-/red-emissive (single-FP component) and dual-emissive (multi-FPs component; kinetic studies not required) FP@SiO2 are prepared without affecting the FP photoluminescence and stabilities (>6months) under dry storage and organic solvent suspensions. Finally, FP@SiO2 color filters are applied to rainbow and white bio-hybrid light-emitting diodes featuring up to 15-fold enhanced stabilities without reducing luminous efficacy compared to references with native FPs. Overall, an easy, versatile, and effective FP-stabilization method is demonstrated in FP@SiO2 toward sustainable protein lighting.

InGaN blue resonant cavity micro-LED with RGY quantum dot layer for broad gamut, efficient displays

The technology of RGBY micro resonant cavity light emitting diodes (micro-RCLEDs) based on quantum dots (QDs) is considered one of the most promising approaches for full-color displays. In this work, we propose a novel structure combining a high color conversion efficiency (CCE) QD photoresist (QDPR) color conversion layer (CCL) with blue light micro RCLEDs, incorporating an ultra-thin yellow color filter. The additional TiO2 particles inside the QDPR CCL can scatter light and disperse QDs, thus reducing the self-aggregation phenomenon and enhancing the eventual illumination uniformity. Considering the blue light leakage, the influences of adding different color filters are investigated by illumination design software. Finally, the introduction of low-temperature atomic layer deposition (ALD) passivation protection technology at the top of the CCL can enhance the device's reliability. The introduction of RGBY four-color subpixels provides a viable path for developing low-energy consumption, high uniformity, and efficient color conversion displays.

Universal deep demosaicking for sparse color filter arrays

Sparse color filter array (CFA) is a potential alternative for the commonly used Bayer CFA, which uses only red (R), green (G), and blue (B) pixels. In sparse CFAs, most pixels are panchromatic (white) ones and only a small percentage of pixels are RGB pixels. Sparse CFAs have the motivation of human visual system and superior low-light photography performance. However, most of the associated demosaicking methods highly depend on synthetic images and are limited to a few specific CFAs. In this paper, we propose a universal demosaicking method for sparse CFAs. Our method has two sequential steps: W-channel recovery and RGB-channel reconstruction. More specifically, it first uses the W channel inpainting network (WCI-Net) to recover the W channel. The first layer of WCI-Net performs the scatter-weighted interpolation, which enables the network to work with various CFAs. Then it employs the differentiable guided filter to reconstruct the RGB channels with the reference of recovered W channel. The differentiable guided filter introduces a binary mask to specify the positions of RGB pixels. So it can handle arbitrary sparse CFAs. Also, it can be trained end-to-end and hence could obtain superior performance but do not overfit the synthetic images. Experiments on clean and noisy images confirm the advantage of the proposed demosaicking method.

Enhancing Thickness Uniformity of Nb2O5/SiO2 Multilayers Using Shadow Masks for Flexible Color-Filtering Applications.

Using a stainless shadow mask combined with a magnetron-ion-assisted deposition (IAD) sputtering system, we investigate the surface morphologies and optical properties of microfilms. Optimal color-filter (CF) coating microfilms with niobium pent-oxide (Nb2O5)/silicon dioxide (SiO2) multilayers on a hard polycarbonate (HPC) substrate, grown at 85 °C and 50 SCCM oxygen flow, can obtain a fairly uniform thickness (with an average roughness of 0.083 and 0.106 nm respectively for Nb2O5 and SiO2 films) through all positions. On a flexible HPC substrate with the Nb2O5/SiO2 microfilms, meanwhile, the peak transmittances measured in the visible range are 95.70% and 91.47%, respectively, for coatings with and without a shadow mask for this new-tech system. For the optimal CF application with a shadow mask, transmittance on each 100 nm band-pass wavelength is enhanced by 4.04% absolute (blue), 2.96% absolute (green), and 2.12% absolute (red). Moreover, the developed new-tech system not only enhances the quality of the films by achieving smoother and uniform surfaces but also reduces deposition time, thereby improving overall process efficiency. For the with-shadow-mask condition, there is little shift at 50% transmittance (T50%), and high transmittance (~97%) is maintained after high-temperature (200 °C) baking for 12 h. These results are well above the commercial CF standard (larger than 90%) and demonstrate reliability and good durability for flexible optical applications.

CFA-Based Splicing Forgery Localization Method via Statistical Analysis

The color filter array of the camera is an effective fingerprint for digital forensics. Most previous color filter array (CFA)-based forgery localization methods perform under the assumption that the interpolation algorithm is linear. However, interpolation algorithms commonly used in digital cameras are nonlinear, and their coefficients vary with content to enhance edge information. To avoid the impact of this impractical assumption, a CFA-based forgery localization method independent of linear assumption is proposed. The probability of an interpolated pixel value falling within the range of its neighboring acquired pixel values is computed. This probability serves as a means of discerning the presence and absence of CFA artifacts, as well as distinguishing between various interpolation techniques. Subsequently, curvature is employed in the analysis to select suitable features for generating the tampering probability map. Experimental results on the Columbia and Korus datasets indicate that the proposed method outperforms the state-of-the-art methods and is also more robust to various attacks, such as noise addition, Gaussian filtering, and JPEG compression with a quality factor of 90.

SootImage: An image recreation, post-processing validation procedure for sooting axisymmetric flames

Validation is a vital part of any computational fluid dynamics study. Validation is done by comparing the computed results to the experimental measurements performed in a known configuration. In sooting flames, such a comparison is non-trivial since the measurements have a wide range of uncertainty due to difficulties in directly measuring soot volume fractions. This work introduces a different way to verify the computations using a software package called SootImage. In this proposed methodology, comparisons are not made directly to the computed properties of interest (soot volume fraction and temperature). Instead, a post-processing procedure is performed to obtain an image of the flame based on the computed properties. This reconstructed image is compared to an actual image of the flame being studied. The algorithm of the image reconstruction utilized within SootImage is presented in detail. Finally, the usage of SootImage is demonstrated on a co-flowing, laminar ethylene/air diffusion flame. Program summaryProgram Title: SootImageCPC Library link to program files:https://doi.org/10.17632/nc5myw64km.1Developer's repository link:https://github.com/VictorChernov/SootImageLicensing provisions: CC BY NC 3.0Programming language: MATLABNature of problem: The software allows comparing images of a real flame with the recreated image of a simulated flame. This requires two major steps. One is the recreation of the image of an axisymmetrical flame from the computed soot volume fraction and temperature fields for a known camera and optical configuration. The second is cropping and position images to obtain a meaningful comparison.Solution method: The solution recreates the image by integrating the soot thermal radiation over a line-of-sight. Soot is assumed to emit as gray body. The integrated radiation is passed through the color filters of the camera and is translated to pixel values. After the process is done for the whole flame, the width, height and origin of both flames are found, and images that can be easily compared are created.

Multi-frame demosaicing for the Quad Bayer CFA in the color difference domain

Recently, imaging systems with submicron image sensors have been increasingly adopting the Quad Bayer color filter array (CFA) owing to its high sensitivity under low illumination conditions when pixel binning techniques are employed. Conversely, under sufficient illumination conditions, direct demosaicing methods are required for the Quad Bayer color filter array to obtain a full-resolution color image. However, the Quad Bayer color filter array is more susceptible to aliasing artifacts because of its structural disadvantages compared to the Bayer color filter array. In this paper, we propose the multi-frame demosaicing method to address this problem. The proposed method assesses local spatial contributions within local windows at each pixel to reconstruct the lost spatial resolution caused by aliasing. Additionally, we utilize the color difference domain to exploit inter-channel correlations, aiming to alleviate color artifacts and enhance spatial resolution. The experimental results demonstrate that our proposed method outperforms other methods, both quantitatively and qualitatively, including single-frame-based demosaicing methods and another multi-frame demosaicing method with pixel binning techniques.