Color Reproduction Research Articles

Comparative Colour Gamut Analysis Of Piezoelectric Inkjet (PIJ) And Sheet-Fed Offset Prinitng Technologies

This paper presents a comprehensive comparative analysis of the colour gamut achieved by Piezoelectric Inkjet (PIJ) and Sheet-Fed Offset printing technologies. The colour gamut, a crucial aspect of print quality, is a measure of the range of colours a printing process can reproduce. Both PIJ and Sheet-Fed Offset printing are widely employed in various industries, including graphic arts and commercial printing. The research methodology involves the characterization of the colour gamut of PIJ and Sheet-Fed Offset printing through empirical experiments and spectral measurements. A diverse set of colour targets is used to assess the gamut volume, including standard colorimetric tests such as colour gamut volume measurements. The study also considers factors such as substrate type, ink formulations, and printing conditions to provide a comprehensive understanding of the gamut limitations and advantages of each technology. Results reveal the strengths and weaknesses of both printing methods in terms of colour reproduction, highlighting areas where one technology may outperform the other. Insights gained from this comparative analysis can inform decision-making processes for print industry professionals, helping them choose the most suitable printing technology based on specific project requirements and desired colour outcomes. Ultimately, this research contributes valuable knowledge to the ongoing discourse on print technology selection, aiding in the optimization of colour reproduction processes for diverse applications ranging from high-quality graphics to commercial printing.

Effect of Polarization on RGB Imaging and Color Accuracy/Fidelity

The use of polarization while trying to keep the digital color reproduction accuracy at its finest is very challenging due to how polarization is interacting and affecting the light spectrum itself and due to the quality of the used polarization materials. Our study on RGB imaging and color reproduction’s fidelity with and without polarization shows that a cross circular polarization (on a camera lens and light source) will have a major impact on how a linear grayscale, whether it has a semi-glossy or matt finishing, would be reproduced in contrast to no polarization at all. A major loss in deep black shades in the case of a semi-glossy grayscale is unmistakable. In addition to a noticeable shift in both lightness and Chroma components regardless of the grayscale’s finishing but depending rather on the used color target for correction. DE00 could not paint the full picture about color fidelity despite its low conformant reported values. Whereas, a closer visual inspection of the color components separately (lightness and Chroma) reveals color reproduction problems caused by polarization.

Color Reproduction in LED Wall Virtual Production Stages

Virtual production stages with LED walls utilize illumination, display, and camera equipment which was not designed with this use case in mind. Because the spectral sensitivity of a camera is different from a human observer, a device specific calibration is required. Furthermore, the illumination spectrum emitted by the display contains large gaps in the cyan and yellow wavelength ranges and is dissimilar to the light sources for which cameras are designed. This causes object colors to be reproduced by the camera in an unnatural manner, making cinematographers hesitant to use LED walls as their primary light source. In this paper, a display calibration and camera color correction workflow for LED wall virtual production stages is proposed. A linear color correction matrix and the spectrum of a multi-channel LED fixture are jointly optimized to better reproduce object colors simultaneously illuminated by an LED display and the multi-channel fixture as they would appear under high CRI (Color Rendering Index) light sources. An alternative color correction method using root polynomials is found to further improve color reproduction. It is shown that the camera’s response to the display can be characterized by a linear 3×3 matrix and the display can be calibrated using the inverse of the color correction, allowing for a color accurate reproduction of a virtual environment.

A Revised Formulation based on CIECAM16 for Cross-media Colour Reproduction via Real Scene Experiment

In order to reproduce the colour appearance between real scene and images on self-luminous display, this study conducted a series of psychophysical experiments using threshold method. Three types of real scenes were built up in a lighting room, including painting, fruit and vegetable, skin colour chart. Sixteen adapting conditions were designed including four CCTs (3000K, 4500K, 6500K, 8000K) and 4 luminance levels (10lux, 100lux, 500lux, 1000lux). Four displays with different sizes were studied. The result indicated that the colour appearance of real scene and the image on the display were different, especially for low CCT and luminance level. The contents of scene and size of display didn’t show a significate impact. The prediction performance of CIECAM16 was tested, and a revised formulation was proposed with high accuracy.

Water-soluble multifunctional red luminescent materials constructed by macrocycle–ligand–lanthanide synergetic assembly strategy

The high-efficiency red luminescent materials in water are attractive in the field of luminescent materials. In particular, those red luminescent materials with multifunctional intelligent responsiveness and good stability are very challenging and important. In this work, a purplish red emission is achieved by a synergetic supramolecular amphiphilic assembly strategy based on the water-soluble macrocyclic calixpyridinium, the bidentate ligand bathophenanthrolinedisulfonic acid disodium salt (BPhDS) and the lanthanide Eu3+. BPhDS and Eu3+ could only form a simple complex emitting a purplish blue fluorescence. Calixpyridinium and BPhDS could construct a spherical assembly. Benefitting from its pH-responsive fluorescence emission, by precise fine-tuning of its pH, a perfect white light emission was obtained and applied in a fluorescent ink. White light is an ideal light source because it has a perfect color reproducibility and stability. More excitingly, a purplish red emission is achieved by calixpyridinium-assisted amphiphilic assembly of non-red emissive BPhDS−Eu3+ complex in water. It paves a new way to construct the high-efficiency red luminescent material based on a lanthanide complex in water and exhibits many advantages: (1) all the assembly components are easy-to-get and the synergetic assembly process is very simple; (2) the supramolecular amphiphilic assembly has a synergetic effect on the luminescence of lanthanide complex in water: the natural hydrophobic inner of the assembly can expel the water molecules around lanthanide complexes and reduce the number of coordination water; the binding of the ligand by macrocycle can limit its rotation, increase its rigidity and reduce its energy loss; the synergetic assembly can shorten the distance of donor–acceptor complexes and enhance their energy transfer efficiency; (3) although the luminescent material does not contain any responsive site, the multiple weak and therefore reversible non-covalent interactions endow it with many intelligent responsiveness in various applications, such as temperature-controlled switch, anti-counterfeit material, and confidential material.

Estimation of Motion Sickness in Automated Vehicles using Stereoscopic Visual Simulation

Structure-aware halftoning algorithms aim at improving their non-structure-aware version by preserving high-frequency details, structures, and tones and by employing additional information from the input image content. The recently proposed achromatic structure-aware Iterative Method Controlling the Dot Placement (IMCDP) halftoning algorithm uses the angle of the dominant line in each pixel’s neighborhood as supplementary information to align halftone structures with the dominant orientation in each region and results in sharper halftones, gives a more three-dimensional impression, and improves the structural similarity and tone preservation. However, this method is developed only for monochrome halftoning, the degree of sharpness enhancement is constant for the entire image, and the algorithm is prohibitively expensive for large images. In this paper, we present a faster and more flexible approach for representing the image structure using a Gabor-based orientation extraction technique which improves the computational performance of the structure-aware IMCDP by an order of magnitude while improving the visual qualities. In addition, we extended the method to color halftoning and studied the impact of orientation information in different color channels on improving sharpness enhancement, preserving structural similarity, and decreasing color reproduction error. Furthermore, we propose a dynamic sharpness enhancement approach, which adaptively varies the local sharpness of the halftone image based on different textures across the image. Our contributions in the present work enable the algorithm to adaptively work on large images with multiple regions and different textures.

Research on the deep learning-based exposure invariant spectral reconstruction method.

The surface spectral reflectance of an object is the key factor for high-fidelity color reproduction and material analysis, and spectral acquisition is the basis of its applications. Based on the theoretical imaging model of a digital camera, the spectral reflectance of any pixels in the image can be obtained through spectral reconstruction technology. This technology can avoid the application limitations of spectral cameras in open scenarios and obtain high spatial resolution multispectral images. However, the current spectral reconstruction algorithms are sensitive to the exposure variant of the test images. That is, when the exposure of the test image is different from that of the training image, the reconstructed spectral curve of the test object will deviate from the real spectral to varying degrees, which will lead to the spectral data of the target object being accurately reconstructed. This article proposes an optimized method for spectral reconstruction based on data augmentation and attention mechanisms using the current deep learning-based spectral reconstruction framework. The proposed method is exposure invariant and will adapt to the open environment in which the light is easily changed and the illumination is non-uniform. Thus, the robustness and reconstruction accuracy of the spectral reconstruction model in practical applications are improved. The experiments show that the proposed method can accurately reconstruct the shape of the spectral reflectance curve of the test object under different test exposure levels. And the spectral reconstruction error of our method at different exposure levels is significantly lower than that of the existing methods, which verifies the proposed method's effectiveness and superiority.

Microstructure of Brownish and Blackish Color on Bizen Stoneware Fired in a Firewood Kiln and Reproduction of Brownish Color

Bizen stoneware is produced by firing shaped green clay in a firewood kiln at around 1200°C. The brownish and blackish colors that appear on the stoneware surface in a firewood kiln do not appear on stoneware heated in an electric furnace. The brownish color was found to be caused by the formation of single crystalline, branched, dendritic, Al-substituted ε-Fe2O3 particles. Composite particles consisting of Al-substituted ε-Fe2O3 and Fe-substituted spinel solid solution also formed on the stoneware surface. In this study, we successfully prepared brownish samples that were similar in color to Bizen stoneware by annealing at 1200°C for 2 h in air after heating Bizen clay pellets with K2CO3 at 1230°C under a 10 vol% CO and 90 vol% Ar gas mixture in an electric furnace instead of firing in a firewood kiln. Dendritic hematite particles also formed on the reproduced samples. The blackish color on Bizen stoneware fired in a firewood kiln was caused by the formation of augite [(Ca,Mg,Fe)2Si2O6], which was produced by a reaction between the Bizen clay and firewood ash.

The Case of Geoffrey Chaucer and Cecily Chaumpaigne: New Evidence

The Case of Geoffrey Chaucer and Cecily Chaumpaigne: New Evidence

Low-Light Image Enhancement Using Photometric Alignment with Hierarchy Pyramid Network.

Low-light image enhancement can effectively assist high-level vision tasks that often fail in poor illumination conditions. Most previous data-driven methods, however, implemented enhancement directly from severely degraded low-light images that may provide undesirable enhancement results, including blurred detail, intensive noise, and distorted color. In this paper, inspired by a coarse-to-fine strategy, we propose an end-to-end image-level alignment with pixel-wise perceptual information enhancement pipeline for low-light image enhancement. A coarse adaptive global photometric alignment sub-network is constructed to reduce style differences, which facilitates improving illumination and revealing under-exposure area information. After the learned aligned image, a hierarchy pyramid enhancement sub-network is used to optimize image quality, which helps to remove amplified noise and enhance the local detail of low-light images. We also propose a multi-residual cascade attention block (MRCAB) that involves channel split and concatenation strategy, polarized self-attention mechanism, which leads to high-resolution reconstruction images in perceptual quality. Extensive experiments have demonstrated the effectiveness of our method on various datasets and significantly outperformed other state-of-the-art methods in detail and color reproduction.

Self-assembly of POSS-Polystyrene Bottlebrush Block Copolymers on an Angle-Robust Selective Absorber for Enhancing the Purity of Reflective Structural Color.

A facile approach for improving color purity is explored by the introduction of an angle-robust selective absorber (ARSA) into bottlebrush block copolymer (BBCP)-based one-dimensional (1D) photonic crystals (PCs). The BBCPs of poly[(3-(12-(cis-5-norbornene-exo-2,3-dicarboximido)dodecanoylamino)propyl POSS)-block-(norbornene-graft-styrene)], Px (x = 1-4), with ultrahigh molecular weights (Mn ∼ 2260 kDa) and low dispersities (D̵ ∼ 1.07) are synthesized by ring-opening metathesis polymerization. The 1D PCs of the lamellar structure are fabricated by self-assembly of the BBCP with different periodicities for full color-generation (blue, green, and red). The optically tailored substrate (i.e., ARSA) is used to modulate the spectral line shape with selective absorption in the near-infrared range. Optical simulation proposes the optimized 1D PC structures on the ARSA, and it provides the reproducibility of the predictable color. The simulated structures are well matched with the experimental results, verifying the enhancement of color saturation even at various incident angles (0-70°).

Review: Louis Kahn: The Importance of Drawing and Our Days Are Like Full Years: A Memoir with Letters from Louis Kahn

Review: <i>Louis Kahn: The Importance of Drawing</i> and <i>Our Days Are Like Full Years: A Memoir with Letters from Louis Kahn</i>

Intelligent Identification of Early Esophageal Cancer by Band-Selective Hyperspectral Imaging.

Simple SummaryEarly esophageal cancer detection is crucial for patient survival; however, even skilled endoscopists find it challenging to identify the cancer cells in the early stages. In order to categorize and identify esophageal cancer using a single shot multi-box detector, this research presents a novel approach integrating hyperspectral imaging by band selection and a deep learning diagnostic model. Based on the pathological characteristics of esophageal cancer, the pictures were categorized into three stages: normal, dysplasia, and squamous cell carcinoma. The findings revealed that mAP in WLIs, NBIs, and HSI pictures each achieved 80%, 85%, and 84%, respectively. The findings of this investigation demonstrated that HSI contains a greater number of spectral characteristics than white-light imaging, which increases accuracy by roughly 5% and complies with NBI predictions.In this study, the combination of hyperspectral imaging (HSI) technology and band selection was coupled with color reproduction. The white-light images (WLIs) were simulated as narrow-band endoscopic images (NBIs). As a result, the blood vessel features in the endoscopic image became more noticeable, and the prediction performance was improved. In addition, a single-shot multi-box detector model for predicting the stage and location of esophageal cancer was developed to evaluate the results. A total of 1780 esophageal cancer images, including 845 WLIs and 935 NBIs, were used in this study. The images were divided into three stages based on the pathological features of esophageal cancer: normal, dysplasia, and squamous cell carcinoma. The results showed that the mean average precision (mAP) reached 80% in WLIs, 85% in NBIs, and 84% in HSI images. This study′s results showed that HSI has more spectral features than white-light imagery, and it improves accuracy by about 5% and matches the results of NBI predictions.

보그 런웨이에 나타난 차이니즈 포복 스타일

This study aims to support design inspired by Asian traditional costumes and broaden the scope of design thinking in the future through examination of the method of expression and characteristics of Chinese robe styles appearing in the Vogue runway collections. To the this, the study reviews how the Chinese traditional robe design has changed through history. First, this study found that the length, style of fastening, and collar and sleeve style have differed and transformed from the period of Pre-Qin to the Republic of China. Colors used for robes included those based on the thoughts of the five elements and various traditional Chinese patterns. Second, the study analyzed Chinese robe styles on the Vogue runway over the last five years. Styles of robe from all the periods of history analyzed in part one appeared in the collections, but the method of expression related to qipao was relatively dominant. In terms of color, combinations were based on trends relating to designers or characteristics of brands rather than reproduction of original colors or combinations of colors in traditional, historical Chinese robes. Patterns used were either animals such as dragons or phoenix or traditional geometric designs. A comprehensive review of the sample showed, among others, characteristics such as the convergence of various robe shapes and western fashion materials according to historic changes, the application of robes to fashion style, design inspired by the decorative expression of robe, and a combination of qipao-shaped futuristic fashion trend.

Investigation of highly luminescent inorganic perovskite nanocrystals synthesized using optimized ultrasonication method

All-inorganic halide perovskite nanocrystals are next-generation materials with excellent optical and semiconductor properties suitable for display applications. In this study, we introduce an optimized ultrasonication method for the high-capacity synthesis of highly luminescent inorganic perovskite nanocrystals. After the synthesis of CsPbBr3 with superior optical performance by ultrasonication method, halide anion exchange was performed to tune the stable emission wavelength over the entire visible range. In particular, the maximum photoluminescence wavelengths of the red and green perovskite nanocrystals were appropriate for light-emitting diode applications, and their full-width-at-half-maximum were very narrow, showing outstanding color purity. The materials also had excellent thermal and photo-stability, which is a necessary requirement for perovskite nanocrystal/organic light-emitting diode hybrid device applications. We formulated uniformly stable perovskite nanocrystal inks and optimized their physical and rheological properties for successful inkjet-printing. Finally, we fabricated a hybrid device with a color conversion layer based on the red and green perovskite nanocrystals synthesized using the optimized ultrasonication and halide-ion-exchange methods. The color reproduction range of the fabricated devices was 27.3 % wider than that of the National Television System Committee values, indicating very vivid colors.

Large-scale vivid metasurface color printing using advanced 12-in. immersion photolithography

Nanostructures exhibiting optical resonances (so-called nanoantennas) have strong potential for applications in color printing and filtering with sub-wavelength resolution. While small scale demonstrations of these systems are interesting as a proof-of-concept, their large scale and volume fabrication requires deeper analysis and further development for industrial adoption. Here, we evaluate the color quality produced by large size nanoantenna arrays fabricated on a 12-in. wafer using deep UV immersion photolithography and dry etching processes. The color reproduction and quality are analyzed in context of the CIE color diagram, showing that a vivid and vibrant color palette, almost fully covering the sRGB color space, can be obtained with this mass-manufacturing-ready fabrication process. The obtained results, thus, provide a solid foundation for the potential industrial adoption of this emerging technology and expose the limits and challenges of the process.

Time-scheduled exposure method for full-color high diffraction efficiency and uniformity of a photopolymer

A full-color reflection holographic optical element (HOE) with uniform diffraction efficiency, achieved via time-scheduled exposure, is proposed in which 660, 532, and 473 nm wavelengths are used for recording. To enhance the diffraction efficiency, the exposure energy of three wavelengths should be controlled to react uniformly in the photopolymer. The photopolymer’s optical characteristics present that the absorptance of the three wavelengths differs, moreover, the reactivity of the photopolymer to exposures is variant at the three wavelengths. The high-efficiency full-color HOE is implemented by determining the pre-exposure times of the three lasers for a set beam intensity. In order to verify the proposed method, we conduct repetitive optical experiments and analyze the results. Finally, a full-color reflection hologram is manufactured with an average efficiency of 61.6 % (standard deviation, 0.5) when the beam intensity of the three lasers is 0.4 mW/cm2. The reconstructed images of the full-color hologram show good uniformity and color reproduction.

Spectral Reflectance Reconstruction Based on BP Neural Network and the Improved Sparrow Search Algorithm

To solve the problem of metamerism in the color reproduction process, various spectral reflectance reconstruction methods combined with neural network have been proposed in recent years. However, these methods are generally sensitive to initial values and can easily converge to local optimal solutions, especially on small data sets. In this paper, we propose a spectral reflectance reconstruction algorithm based on the Back Propagation Neural Network (BPNN) and an improved Sparrow Search Algorithm (SSA). In this algorithm, to solve the problem that BPNN is sensitive to initial values, we propose to use SSA to initialize BPNN, and we use the sine chaotic mapping to further improve the stability of the algorithm. In the experiment, we tested the proposed algorithm on the X-Rite ColorChecker Classic Mini Chart which contains 24 colors, the results show that the proposed algorithm has significantly better performance compared to other algorithms and moreover it can meet the needs of spectral reflectance reconstruction on small data sets. Code is avaible at https://github.com/LuraZhang/spectral-reflectance-reconsctuction.

Developing a digital archive system for imperial Chinese robe in the Qing Dynasty.

The digital archive of cultural heritage provides new opportunities for the protection of the cultural heritage and the development of online museums. One of the essential requirements for the digitization is to achieve accurate color reproduction. Taking the Imperial Chinese robes in the Qing Dynasty as an example, this study aims to develop a digital achieve system to digitize the robes using a high-end imaging system and accurately reproduce their color properties on a display. Currently, there has been very limited study focused on the color reproduction of silk fabrics or other textile materials. The conventional color management process using a traditional color chart, however, may not be suitable for the reproduction of silk fabrics because they have very high gloss. To address this difficulty, a unique “Qianlong Palette” color chart, consisting of 210 silk fabric samples, has been specifically produced for optimizing the color reproduction of silk fabrics and a color image reproduction system has been developed for the digitization and archiving of the clothing fabric for the royal court. Color characterization models using both the “Qianlong Palette” color chart and the traditional color chart, and different mapping methods, are compared and the model with highest accuracy used in a self-programmed interface for automatically processing textile images in the future. Finally, the digital archive system has been validated using six garments of silk fabric relics. The color differences after the color image reproduction are all less than 3.00ΔE*ab, indicating acceptable color reproduction of the system. The images after color reproduction have also been evaluated subjectively by experts from the museum and the results are considered satisfactory. Our results show that the newly designed “Qianlong Palette” color chart exhibits superior performance over the conventional color chart in effectively predicting the color of the silk fabrics. The self-programmed graphical user interface for image color management can serve as a powerful tool to truly reproduce the color of various silk fabric relics in museums in the future and digitally archive those valuable cultural relics for different uses.

Does External Illumination Affect Color Acceptability Threshold for a Mixed Display Technology Cockpit?

Color Acceptability is a complex phenomenon. Contrary to perceptibility, color acceptability is defined as the level of color difference that is considered under the limit of preferred color reproduction on two media. A system comprising two automotive OLED and LCD displays was used in this experiment. A previous study (presented at [1]) by the authors had identified this limit for a daylight scenario where an external illumination of 3000 Lux at 5300K was illuminating the surface of the displays. In this study a night-time driving scenario was simulated with a projector light source illuminating the displays at 50 lux and 1318K. Statistical analysis is used to quantify statistically significant differences between various conditions. _x005F_x000D_ Introduction