Color Reproduction Research Articles

Improving Accuracy of Color Reproduction on Mobile Displays

Improving Accuracy of Color Reproduction on Mobile Displays

Color Biomimetics in Textile Design: Reproduction of Natural Plant Colors through Instrumental Colorant Formulation.

This paper explores the intersection of colorimetry and biomimetics in textile design, focusing on mimicking natural plant colors in dyed textiles via instrumental colorant formulation. The experimental work was conducted with two polyester substrates dyed with disperse dyes using the exhaustion process. Textiles dyed with different dye colors and concentrations were measured in a spectrophotometer and a database was created in Datacolor Match Textile software version 2.4.1 (0) with the samples' colorimetric properties. Colorant recipe formulation encompassed the definition and measurement of the pattern colors (along four defined natural plants), the selection of the colorants, and the software calculation of the recipes. After textile dyeing with the lowest expected CIELAB color difference (ΔE*) value recipe for each pattern color, a comparative analysis was conducted by spectral reflectance and visual assessment. Scanning electron microscopy and white light interferometry were also used to characterize the surface of the natural elements. Samples dyed with the formulated recipe attained good chromatic similarity with the respective natural plants' colors, and the majority of the samples presented ΔE* between 1.5 and 4.0. Additionally, recipe optimization can also be conducted based on the colorimetric evaluation. This research contributes a design framework for biomimicking colors in textile design, establishing a systematic method based on colorimetry and color theory that enables the reproduction of nature's color palette through the effective use of colorants.

Conservation Measures for Media Art According to Technological Changes: Color Reproducibility Comparison for Conservation of Artwork Using Video Display

Artworks using display devices require conservation treatment due to aging or discontinuation of media. However, irreversible conservation treatment methods such as modification and change of existing media may be included, which may infringe on the right to secure the originality and maintain the identity of the work. Accordingly, a comparative study on the theoretical background and color reproduction elements was conducted to provide basic data for mid to long-term conservation to confirm the possibility of replacing works using discontinued CRT with LCD. Video art is a modern art form that uses video technology as an artistic expression medium and has technology dependence. Therefore, as the conversion of the used medium is appropriate, the materials added in the conservation process are seen as part of securing the originality in terms of ‘material conservation’. An experiment was conducted to compare the color characteristics of CRT and LCD. As a result of the experiment, it was confirmed that the luminance and chromaticity stability of LCD was relatively excellent through the measurement results of spectral distribution, chromatic change difference, background dependence, and time stability, confirming the possibility of alternative application.

Fading and Color Reproducibility of Nipple-Areola Tattoos in Asian Patients.

Background The purpose of this study was to clarify fading, red, green, and blue values (RGB) change, and color reproducibility for nipple-areola complex (NAC) tattoos. Methods NAC tattooing was performed on 60 sites in 59 Japanese patients prospectively. The evaluation was assessed using digital photo, Casmatch standardization, and RGB and luminance values preoperatively, immediately after, 1 week, 1, 3, 6, and 12 months after tattooing. RGB and luminance values changes over time, time-adjusted fading rate, and the rate of luminance at 12 months were calculated. In color reproducibility study ( n = 34), RGB values after 12 months were compared with the color sample about dark/reddish and light/less reddish pigments. Results RGB varied widely from immediately after to 1 month after tattooing. For RGB and luminance, significant differences were seen between pre and immediate after, 1 and 3 months, 3 and 6 months, and 6 and 12 months. In G values, significant differences were seen between all neighboring points. The fading rate tended to decrease as time progresses, but was not significant, that is, fading continued even between 6 and 12 months. Luminance was 9% brighter than contralateral NAC at 12 months. Color reproducibility tended to be higher with dark/reddish pigments, despite no significant differences. Conclusion The fading rate of tattooed NACs tended to decrease as time progresses, but fading still occurs between 6 and 12 months. Luminance was 9% brighter than contralateral NAC at 12 months after.

Diatom Cribellum-Inspired Hierarchical Metamaterials: Unifying Perfect Absorption Toward Subwavelength Color Printing.

Diatom exoskeletons, known as frustules, exhibit a unique multilayer structure that has attracted considerable attention across interdisciplinary research fields as a source of biomorphic inspiration. These frustules possess a hierarchical porous structure, ranging from millimeter-scale foramen pores to nanometer-scale cribellum pores. In this study, this natural template for nanopattern design is leveraged to showcase metamaterials that integrates perfect absorption and subwavelength color printing. The cribellum-inspired hierarchical nanopatterns, organized in a hexagonal unit cell with a periodicity of 300nm, are realized through a single-step electron beam lithography process. By employing numerical models, it is uncovered that an additional induced collective dipole mode is the key mechanism responsible for achieving outstanding performance in absorption, reaching up to 99%. Analysis of the hierarchical organization reveals that variations in nanoparticle diameter and inter-unit-cell distance lead to shifts and broadening of the resonance peaks. It is also demonstrated that the hierarchical nanopatterns are capable of color reproduction with high uniformity and fidelity, serving as hexagonal pixels for high-resolution color printing. These cribellum-inspired metamaterials offer a novel approach to multifunctional metamaterial design, presenting aesthetic potential applications in the development of robotics and wearable electronic devices, such as smart skin or surface coatings integrated with energy harvesting functionalities.

Colour reproduction evaluation of whole-slide imaging scanners for digital pathology

ABSTRACT Digital pathology using whole-slide imaging (WSI) scanners aids pathologists challenged by diagnostic volume and novel diagnostic methods. Colour reproducibility of WSI scanners is crucial for accurate digital diagnoses. We propose an objective and quantitative method for evaluating colour reproduction in digital images of pathological specimens from two perspectives: true colour value reproduction and colour discrimination. We define 57 critical features for evaluation, extract tissue structures, and establish diagnostic criteria. Our method is unique and useful for clinical use. We tested a prototype scanner, and it satisfied all criteria for true colour value reproduction (all the colour samples corresponding to the selected tissue evaluation points were experimentally within the acceptable range) and colour discrimination (the colour difference ΔE2000 calculated from the corresponding colour sample combinations exceeded the lower permissible limit for the selected discrimination points). This evaluation method and WSI scanner can contribute to accurate colour reproduction in digital pathology.

Colorimetric characterization of multispectral imaging systems for visualization of historical artifacts

Multispectral imaging has long been used in the study of cultural heritage artifacts, particularly manuscripts with low-contrast text. The goal of multispectral imaging systems has largely been to enhance the text by imaging outside the spectral response of the human visual system and by applying various image processing techniques. However, there is a desire to use multispectral images for high quality, true color rendering of the artifacts as well. We use two multispectral imaging systems in this work. One of them is the Multispectral Imaging System for the study of Historical Artifacts (MISHA) which has been demonstrated to have significant utility at a lower cost and better ease of use compared to commercially available systems. This system was specifically designed and built for the purpose of imaging artifacts, particularly manuscripts and works on paper with illegible text due to deterioration and other environmental causes. Given this goal of “discovering” low-contrast text (and other features) on planar objects, the system has not been optimized for color reproduction purposes. The second system is a commercially available MegaVision EVTM Spectral Imaging System. This system is also used for cultural heritage imaging. In this work, we develop an approach to colorimetrically characterize these cameras and illumination systems, adding an option for accurate color reproduction to their capabilities. To do this, we present two different approaches. The first approach we call the Color Transformation Method. Here we use a Macbeth ColorChecker to first linearize the camera photometric response, and then find a linear matrix transformation from the camera response to CIEXYZ tristimulus values. The second approach we call the Illuminant Method. Here we consider each output by the camera as a reflectance factor value at the known wavelength of a narrowband illuminator. We then convert these values to the color of the object in terms of CIEXYZ tristimulus values. We show that the Color Transformation Method using a Macbeth ColorChecker leads to a more accurate result. Meanwhile, the Illuminant Method is much simpler and produces acceptable results, particularly considering accurate color reproduction was not a goal in designing the MISHA camera system. The same methods are applied to both imaging systems to show the robustness and applicability of the approaches developed herein to other imaging systems. Results are shown for both quantitative calibration targets as well as artifacts of interest to the field of cultural heritage studies. It is worth noting that we are not comparing the two imaging systems overall or the color processing software available from MegaVision. Rather, we simply show that the two approaches developed here are applicable to different multispectral imaging systems, from a very cost-effective system, i.e., MISHA to a more expensive one, i.e., MegaVision.

Quantitative examination of factors influencing the colour reproduction ability of lithium disilicate glass-ceramics

BackgroundEffects of ceramic translucency, layer thickness, and substrate colour on the shade of lithium disilicate glass-ceramic restorations proved to be significant in several studies, however, quantitative, numerical results on the relationship between the colour difference and these parameters are still lacking. The purpose of this in vitro study was to quantitatively determine how the colour reproduction ability of a lithium disilicate glass-ceramic is affected by its translucency, layer thickness, and substrate colour.MethodsCeramic samples were prepared from A2 shade IPS e.max CAD blocks with high and low translucencies (HT and LT) in a thickness range of 0.5–2.5 mm (+/- 0.05 mm). Layered samples were acquired utilizing composite substrates in 9 shades; transparent try-in paste was used. The spectral reflectance of the specimens was assessed under D65 standard illumination with a Konica Minolta CM-3720d spectrophotometer. The CIEDE2000 colour difference (ΔE00) between two samples was analysed using perceptibility and acceptability thresholds set at 50:50%. Statistical analysis involved linear regression analysis and the Kruskal–Wallis test.ResultsAn increase in the thickness of 0.5 mm reduced the ΔE00 of the HT samples to 72.8%, and that of the T samples to 71.1% (p < 0.0001). 7 substrates with HT and LT specimens had significantly different results from the mean (p < 0.05). A thickness of 0.5 mm is not sufficient to achieve an acceptable result at any level of translucency, while the low translucency ceramic at a thickness of 1.5 mm gave acceptable results, except for severely discoloured substrates (ND8 and ND9).ConclusionsThe colour reproduction ability of lithium disilicate glass-ceramics is significantly affected by their translucency, layer thickness, and 7 substrates out of 9 substrates examined.

High-fidelity color characterization in virtual reality across head mounted displays, game engines, and materials

We present a comprehensive colorimetric analysis of three head mounted displays (HMDs) - HTC Vive Pro Eye, Pimax 8K X DMAS, and Varjo Aero - focusing on their color calibration and uniformity across different game engines (Unity and Unreal) and for different materials/shaders. We developed a robust methodology combining hardware and software tools, including spectroradiometry and imaging colorimetry, to characterize and calibrate these HMDs for accurate color reproduction. The study showcases substantial advancements in colorimetric accuracy, with a reduction in the average deltaE00 of 90% or more across all tested HMDs and conditions. This level of color reproduction quality is below human discrimination thresholds, ensuring that any color inaccuracies remain imperceptible to the human eye. We also identified key areas for improvement, particularly in display uniformity, which could impact peripheral color reproduction. By making our tools and code publicly available, this study aims to facilitate future research and development in virtual reality (VR) technology, emphasizing the importance of color fidelity in virtual environments. The new insight enabled by our work is the extension and application of a traditional calibration method to currently available HMDs.

Irreversible temperature indicator based cellulose membranes conjugated with leuco‐dye pigment

AbstractThis research focuses on the development of thermochromic membranes made of cellulose acetate (CA) for temperature monitoring of sensitive food products. Two dual TC membranes developed for the control of different temperature ranges were formulated using a three‐component system: a leuco‐dye membrane (crystal violet lactone, CVL) integrated with an acidic membrane containing the color developer (salicylic acid) and the acidic solvent with different melting points (decanoic acid, DA, or methacrylic acid, MA). The CVL membrane, together with the DA membrane, showed an irreversible color change when exposed to 35°C, which was facilitated by the melting of DA. The CVL membrane also underwent an irreversible color change when exposed to 15°C together with the MA membrane. The membranes were characterized in detail using scanning electron microscopy. The evaluation of color changes, reproducibility, specificity, and stability ensured the practical suitability of these membranes. Overall, this innovative approach has proven to be a reproducible, sustainable, cost‐effective method to produce irreversible colorimetric temperature sensors. These sensors have significant potential for applications in the food and pharmaceutical industries and offer a promising way to improve product safety and quality.

Vehicle detection in varied weather conditions using enhanced deep YOLO with complex wavelet

Traffic congestion is prevalent in many major and medium-sized cities throughout different countries in contemporary society. In traffic images, various multi-sized vehicles are tightly clustered together and obstructed from one another. Identifying vehicles in such instances is crucial for urban traffic surveillance, safety monitoring, and legal concerns but it also presents major challenges. The remarkable detection accuracy and efficiency of deep learning-based systems have led to their recent and extensive use in vehicle identification. There are significant advanced YOLO models with different backbone architectures and frameworks developed for vehicle detection. Yet, the performance of YOLO variants are facing the challenges of handling false detection against occluded and densely sophisticated scenarios. The proposed model is developed to address such types of limitations, for example; dynamic illumination, noisy images, and scale sensitivity to improve the vehicle detection rate in different traffic scenarios and varying weather conditions. The proposed study employs an improved YOLOv4 to identify moving vehicles in different lighting conditions including daylight, cloudy, rainy, and night. For hybridization, three techniques are utilized such as the Multiscale Retinex, Dual tree complex wavelet transform (DTCWT), and Pulse Coupled Neural Networks (PCNN). The DTCWT is employed for multiscale decomposition and to denoise the complex high frequency subband information, then the denoised subbands are reconstructed into a denoised image. The Multiscale retinex is utilized to reduce the halo artifacts on high-contrast edges and maintain the balance with dynamic range compression and color reproduction. The synchronizing pulse burst property of PCNN is used to detect the isolated noisy pixels and modify the detected noisy pixels. From the results it is worth noting that the developed model surpasses state-of-the-art methods in sunny, night, cloudy, and rainy modes. The proposed method using the DTCWT technique can detect the vehicles with mAP of 91.09% and 35FPS.

The new preferred memory color (PMC) chart

AbstractA color rendition chart, the preferred memory color (PMC) chart, has been produced. It comprises 30 colored patches, divided into three groups: preferred memory colors, reference color‐gamut colors, and a gray scale. The main purpose of the new chart is to enable users to produce satisfactory preferred color reproduction using digital cameras, displays, and printing systems. The methods used to develop the various colors, and the color specification of each color are presented. Finally, several potential applications of the chart for the characterization of imaging devices, for the evaluation of image color quality, and for the calculation of color rendering indices for lighting are suggested.

Pure Green Ag–In–Ga–S/Ga–S Quantum Dot Light‐Emitting Diodes with Electron Transport Materials Exhibiting Enhanced Luminescence Properties

AbstractQuantum dots (QDs) are essential luminescent materials with applications in wide‐color‐gamut displays requiring exceptional color reproducibility. Multinary semiconductor QDs composed of groups I, III and VI elements are expected to serve as eco‐friendly materials to replace conventional QDs owing to the potential narrow spectral widths and tunable bandgaps of the former. Although optimized Ag–In–Ga–S/Ga–S core/shell QDs (AIGS QDs) have exhibited vibrant green emissions, electroluminescence from QD‐based light‐emitting diodes (QLEDs) incorporating these AIGS QDs is reduced as a consequence of the effects of defect sites. The present work therefore examines the incorporation of electron transport materials (ETMs) into AIGS QD emitting layers. A device incorporating emitting layers composed of AIGS QDs and 2,4,6‐tris(3‐(3‐pyridyl)phenyl)‐1,3,5‐triazine (TmPPyTz), with the latter acting as a highly conductive ETM, exhibits a low driving voltage and high efficiency. Furthermore, the addition of two ETMs — TmPPyTz and tris(2,4,6‐trimethyl‐3‐(pyridin‐3‐yl)phenyl)borane — is found to provide enhanced luminescence properties because these materials are deposited in the emitting layer in different forms and hence has varying effects in terms of improving conductivity and charge balance. The resulting QLEDs have a sharp spectral width of 30 nm, suggesting a level of color purity suitable for wide‐color‐gamut displays.

A smartphone image-based method for the colorimetric characterization of historical pigments in mural paintings

In this article, the detailed description of a smartphone-based analytical method to turn a smartphone into a colorimeter is described and applied to mural painting replicas. The method consists of a camera characterization process, to estimate CIELAB values from RGB camera responses, correcting for potential experimental interferences, like the effect of the lighting/capture geometry or software for color modification and enhancement. Next, the estimated CIELAB descriptors were used to build a chemometric Support Vector Classifier to objectively distinguish among the colors of the different pigments. The method was validated in terms of color reproduction and classification performance.•A smartphone-based method is described to capture mural painting color.•A color gamut-specific camera characterization procedure is developed and the performance of the smartphone-based colorimeter is compared with a spectrophotometer.•A classification method based on the estimated CIELAB descriptors is validated in terms of classification performance.

Estimation of color reproduction accuracy using a tunable source based on an acoustic-optical tunable filter

Estimation of color reproduction accuracy using a tunable source based on an acoustic-optical tunable filter

Color arrestor pixels for high-fidelity, high-sensitivity imaging sensors

Abstract Silicon is the dominant material in complementary metal-oxide-semiconductor (CMOS) imaging devices because of its outstanding electrical and optical properties, well-established fabrication methods, and abundance in nature. However, with the ongoing trend toward electronic miniaturization, which demands smaller pixel sizes in CMOS image sensors, issues, such as crosstalk and reduced optical efficiency, have become critical. These problems stem from the intrinsic properties of Si, particularly its low absorption in the long wavelength range of the visible spectrum, which makes it difficult to devise effective solutions unless the material itself is changed. Recent advances in optical metasurfaces have offered new possibilities for solving these problems. In this study, we propose color arrestor pixels (CAPs) as a new class of color image sensors whose composite spectral responses directly mimic those of the human eye. The key idea is to employ linearly independent combinations of standardized color matching functions. These new basis functions allow our device to reproduce colors more accurately than the currently available image sensors with red-green-blue filters or other metasurface-based sensors, demonstrating an average CIEDE2000 color difference value of only 1.79 when evaluating 24 colors from the Gretag-Macbeth chart under standard illuminant D65. Owing to their high fidelity to the human eye response, CAPs consistently exhibit exceptional color reproduction accuracy under various spectral illumination compositions. With a small footprint of 860 nm height and 221 nm full-color pixel pitch, the CAPs demonstrated high absorption efficiencies of 79 %, 81 %, and 63 % at wavelengths of 452 nm, 544 nm, and 603 nm, respectively, and good angular tolerance. With such a high density of pixels efficiently capturing accurate colors, CAPs present a new direction for optical image sensor research and their applications.

A comparative analysis of VGG19 and Magenta models for Neural Style Transfer

In recent years, artificial intelligence (AI) has witnessed remarkable progress, with deep learning techniques playing a pivotal role in this transformative journey. One prominent facet of this progress is Neural Style Transfer (NST), a domain within computer vision and image processing. NST entails merging the content of one image with the stylistic attributes of another, resulting in a seamless fusion of content and style. This paper presents a comprehensive comparative analysis of two influential style transfer models, VGG19 and Magenta, shedding light on their strengths and limitations. VGG19, a well-established convolutional neural network, excels in feature extraction, dimensionality reduction, and image classification, making it ideal for computer vision tasks. In contrast, Magenta, a creative content generation framework, specializes in producing innovative content, such as music and art, while promoting human-AI collaboration. Evaluation reveals that Magenta's generated images tend to exhibit softer colors but higher clarity, while VGG19 produces vibrant and faithful color reproductions with finer details. The choice between these models should be driven by specific task requirements. VGG19 is suitable for tasks emphasizing color fidelity, while Magenta excels in image clarity. Future research directions may involve enhancing algorithmic capabilities to harness the strengths of both models and improving efficiency in style transfer techniques. This analysis empowers researchers, practitioners, and enthusiasts to make informed decisions when selecting a model aligned with their objectives, contributing to the evolving landscape of AI-assisted creative content generation.

Assessment of color reproduction in text-generated images of common natural objects (sky, grass, fallen leaves, rocks) based on memory color

Assessment of color reproduction in text-generated images of common natural objects (sky, grass, fallen leaves, rocks) based on memory color

Effect of enamel thickness and dentin shade of resin composite on the final color reproduction.

Effect of enamel thickness and dentin shade of resin composite on the final color reproduction.

Quality of Colour Rendering in Photographic Scenes Illuminated by Light Sources with Light-Shaping Attachments

In both commercial and scientific photography, achieving accurate colour reproduction is essential. This study investigates the influence of light-shaping attachments on colour rendering indices (CRIs) under various lighting conditions. Through 180 measurements of different lighting combinations, statistical analysis reveals significant interactions between light sources, modifiers, and CRI test colour samples (TCS). Snoots consistently produce superior CRIs, while interactions between light sources and other light modifiers vary, affecting CRIs differently based on spectral distributions and material properties of the modifiers. Combining light sources and modifiers from the same manufacturer is found to enhance colour accuracy. These findings offer valuable insights for photographers, highlighting the importance of understanding light properties and light-shaping attachment effects on colour rendition. By informing best practices, this research contributes to achieving high-quality photographs across commercial and scientific domains, ensuring both accurate data representation and visually appealing results.