Optimal Color Research Articles

Optimizing photochromic reactions of hydrophobic copper-doped zinc sulfide nanocrystals

Abstract Copper-doped zinc sulfide nanocrystals (Cu-ZnS NCs) exhibit durable, temperature-stable photochromic properties with cost-effective synthesis. However, existing photochromic Cu-ZnS NCs are water-soluble, limiting industrial applications. To address this, we synthesized hydrophobic Cu-ZnS NCs using ligands compatible with organic solvents. These NCs display reversible photochromism in several organic solvents, changing from pale yellow to brown under 365-nm light and reverting within tens of minutes. We systematically examined the effects of zinc precursors, particle size, Cu doping concentration, and solvents to optimize the performance and elucidate an optimal coloration condition. This study demonstrates the promise of Cu-ZnS NCs as versatile, next-generation photochromic materials.

Improved artificial rabbits algorithm for global optimization and multi-level thresholding color image segmentation

The Artificial Rabbits Optimization Algorithm is a metaheuristic optimization algorithm proposed in 2022. This algorithm has weak local search ability, which can easily lead to the algorithm falling into local optimal solutions. To overcome these limitations, this paper introduces an Improved Artificial Rabbits Optimization Algorithm (IARO) and demonstrates its effectiveness in multi-level threshold color image segmentation using the Otsu method. Initially, we apply a center-driven strategy to enhance exploration by updating the rabbit’s position during the random hiding phase. Additionally, when the algorithm stalls, a Gaussian Randomized Wandering (GRW) strategy is utilized to enable the algorithm to escape local optima and improve convergence accuracy. The performance of the IARO algorithm is evaluated using 23 standard benchmark functions and CEC2020 benchmark functions, and compared with nine other algorithms. Experimental results indicate that IARO excels in global optimization and demonstrates notable robustness. To assess its effectiveness in multi-threshold color image segmentation, the algorithm is tested on classical Berkeley images. Evaluation metrics including execution time, Peak Signal-to-Noise Ratio (PSNR), Feature Similarity (FSIM), Structural Similarity (SSIM), Boundary Displacement Error (BDE), The Probabilistic Rand Index (PRI), Variation of Information (VOI) and average fitness value are used to measure segmentation quality. The results reveal that IARO achieves high accuracy and fast segmentation speed, validating its efficiency and practical utility in real-world applications.

Inconspicuous breeding coloration to conceal eggs during mouthbrooding in male cardinalfish.

Animals exhibit colorations optimal for their niche, which hides their existence from other organisms. In Apogoninae fishes, the father broods their egg inside their mouth. Since the color of eggs is different from parental fish, it can disrupt the optimal camouflage coloration of parental fish if the lower jaw is transparent. Here, we identified male- and breeding season-specific whitish coloration consisting of iridophores in the lower jaw. Artificial implantation of eggs inside the mouth of females and males showed that iridophores in the lower jaws concealed the conspicuous coloration of eggs only in males. In addition, it was revealed that iridophore development in the lower jaw is induced by androgen through the Alkal-Ltk pathway. These results suggest that androgen-dependent breeding colorations in males, which have been considered to attract females, may serve the opposite function, "inconspicuous breeding coloration" in these species.

Optimal color sets to represent the colors of natural scenes by k-medoids clustering

Optimal color sets to represent the colors of natural scenes by k-medoids clustering

Preparation of durable photonic particles with optimal structural colors

The silica nanosphere-based photonic crystal supraballs demonstrate remarkable structural colors. However, their inadequate mechanical performance limits their potential for extensive industrial applications. In this study, elastomeric polymers were introduced into the internal interstices and surfaces of the supraballs through an emulsion method, forming a protective framework around the structural units. This significantly enhanced the stability and abrasion resistance of the supraballs. Durable supraballs with structural colors were successfully fabricated by optimizing the volume ratio between elastomeric polymers and structural units. Despite the disruption of the close-packed structure typical of photonic crystals caused by the incorporation of elastomeric polymers, the relatively regular arrangement of structural units within the supraballs was sufficient to generate vibrant structural colors. Additionally, durable supraballs in a variety of colors were successfully fabricated by utilizing silica nanospheres with different diameters, meeting the requirements for industrial applications of dyes.

Machine learning-based techno-econo-environmental analysis of CO2-to-olefins process for screening the optimal catalyst and hydrogen color

CO2 to light olefins (CTLO) is an attractive strategy for CO2 fixation to obtain high-value-added chemical products. Selecting the optimal catalyst and hydrogen source for the process has become increasingly challenging due to the wide range of developed catalysts and diverse hydrogen sources available. Herein, this study proposes a machine learning-based techno-econo-environmental analysis framework for screening catalysts and hydrogen colors for the CTLO process. The preferred machine learning model is employed to screen the most promising catalyst for the CTLO process, which is then applied to accomplish the conceptual design of the entire process to obtain essential material and energy balance results by process modeling and simulation. Finally, the techno-econo-environmental performance of the CTLO processes using various colored hydrogen are compared to provide more informed choices. The results indicate the extreme gradient boosting model exhibits superior predictive accuracy, making it suitable for integrating with the genetic algorithm to screen the optimal catalyst for the CTLO process. After multi-objective optimization, an optimal Fe-based catalyst is screened and used for the modeling and simulation of the CTLO process due to its highest light olefins yield (36.43 %). The carbon, hydrogen, and exergy utilization efficiencies of the CTLO process considering solely the target light olefins are 59.58 %, 21.71 %, and 40.41 %, respectively. After evaluating the impact of different H2 colors on the total operating cost, unit production cost, and minimum selling price of the CTLO process, it was found the CTLO process using gray H2 generated by coke oven gas and coal gasification technologies exhibits the most favorable cost-effectiveness and optimal market price compared to alternative production scenarios. However, using green H2 proves highly advantageous for the CTLO process in attaining comprehensive negative carbon emissions throughout its lifecycle. Moreover, it anticipates the influence of technological advancements and market fluctuations on the market competitiveness of CTLO processes with diverse hydrogen colors.

Synergetic construction of color and multifunction for sustainable lyocell fabric by Coptis chinensis and BTCA

In the context of escalating standards of living, the demand for healthy and multifunctional textiles is increasing. As a kind of cellulose macromolecular-based material, lyocell fiber has low carbon, is environmentally friendly, and demonstrates superb performance. The utilization of some Chinese herb dyes solves the pollution problem in the color and functionality construction of lyocell fabric by synthetic dyes and finishing agents. However, problems such as low dye utilization rate, light apparent color, and weak functionality of dyed fabrics remain, thus limiting the further application of the powerful combination of lyocell fabric and Chinese herb dyes. Here, a color and multifunction construction method of lyocell fabric with Coptis chinensis and 1,2,3,4-butanetetracarboxylic acid was proposed. Under the optimal color construction condition, the color depth increased remarkably, and the dye exhaustion rate of the modified fabric enhanced by 332.3 % compared with the unmodified one. The multifunction construction imparted outstanding fuzz and pilling inhibition, fibrillation resistance, and antiwrinkle performance for lyocell fabrics. Moreover, the dyed lyocell fabric exhibited considerable UV protective activity and antibacterial property against Staphylococcus aureus. This work provided an efficient color and multifunction construction technology for lyocell fabric with high value added.

Enhancing Underwater Images through Multi-Frequency Detail Optimization and Adaptive Color Correction

This paper presents a novel underwater image enhancement method addressing the challenges of low contrast, color distortion, and detail loss prevalent in underwater photography. Unlike existing methods that may introduce color bias or blur during enhancement, our approach leverages a two-pronged strategy. First, an Efficient Fusion Edge Detection (EFED) module preserves crucial edge information, ensuring detail clarity even in challenging turbidity and illumination conditions. Second, a Multi-scale Color Parallel Frequency-division Attention (MCPFA) module integrates multi-color space data with edge information. This module dynamically weights features based on their frequency domain positions, prioritizing high-frequency details and areas affected by light attenuation. Our method further incorporates a dual multi-color space structural loss function, optimizing the performance of the network across RGB, Lab, and HSV color spaces. This approach enhances structural alignment and minimizes color distortion, edge artifacts, and detail loss often observed in existing techniques. Comprehensive quantitative and qualitative evaluations using both full-reference and no-reference image quality metrics demonstrate that our proposed method effectively suppresses scattering noise, corrects color deviations, and significantly enhances image details. In terms of objective evaluation metrics, our method achieves the best performance in the test dataset of EUVP with a PSNR of 23.45, SSIM of 0.821, and UIQM of 3.211, indicating that it outperforms state-of-the-art methods in improving image quality.

Eco‐friendly ultrasonic‐assisted appraisal of herbal‐based yellow natural colorant for silk dyeing

AbstractThe global recognition of eco‐friendly products like plant‐based dyes is escalating, driven by their exceptional biological and Ayurvedic attributes. This study isolates colorants from mango turmeric (Curcuma aromatica) using ultrasonic irradiation, supplemented with bio‐mordants to enhance color retention. Through the utilization of Response Surface Methodology and Central Composite Design, a technique that was optimized was completed to maximize coloring variables using statistical analysis. Results from 32 experimental runs reveal that optimal color depth (K/S = 19.399) was achieved with ultrasonic‐treated silk fabric (20 min exposure) using 65 mL of irradiated aqueous extract (20 min) with a pH of 5, supplemented with 1.5 g/100 mL salt of sodium chloride, maintained the temperature 75°C for the 45 min. Precoloring treatment with acacia, pomegranate, and pistachio extracts at specified concentrations enhanced colorfastness. Postdyeing, alterations in the concentrations of these extracts led to further improvements in colorfastness. Notably, adding Al+3 and Fe+2 salts, alongside tannic acid, exhibited notable effects in both pre‐ and postdyeing stages. While the colorfastness properties of unmordated silk fabric was lower than mordanted dyed silk fabric. Irradiation with ultrasonic waves significantly boosted the amount of dye that could be extracted from rhizomes of mango turmeric. Moreover, the application of bio and synthetic mordants in a strategic manner led to colorfastness ratings on silk fabric that ranged from excellent to satisfactory. This research underscores ultrasonic technologies and bio‐mordants' efficacy in sustainable dyeing processes, offering insights for developing eco‐friendly textile coloration methods.

Enhancing Red Table Grape Coloration Using Tsikoudia: A Novel and Sustainable Approach.

Achieving optimal coloration in red table grapes, especially in warm-climate regions, presents significant challenges due to high temperatures that inhibit anthocyanin biosynthesis. Conventional methods to enhance grape coloration, including the use of abscisic acid (ABA), ethephon, foliar nutrient supplementation, and viticultural practices like cluster trimming and girdling, have limitations related to cost, regulatory restrictions, and potential adverse effects on grapes quality. This study proposes the application of tsikoudia, a traditional Greek alcoholic beverage, as a novel, sustainable, and cost-effective alternative to conventional practices. Tsikoudia, applied during the veraison stage, significantly improved the coloration of 'Crimson Seedless' and 'Red Globe' grapes by enhancing anthocyanin accumulation and altering color parameters. Specifically, lightness (L*), chroma (C*), and hue angle (h), measured using the CIE-Lab color system, were reduced, while the Color Index for Red Grapes (CIRG) was increased. Additionally, total anthocyanin content, determined through spectrophotometric analysis, also showed an increase. These changes indicate a more intense red coloration. This research highlights the effectiveness of tsikoudia in improving grape coloration and contributes to the development of more sustainable viticultural practices.

Your Eyes on Speed: Using Pupil Dilation to Adaptively Select Speed-Reading Parameters in Virtual Reality

Rapid Serial Visual Presentation (RSVP) improves the reading speed for optimizing the user's information processing capabilities on Virtual Reality (VR) devices. Yet, the user's RSVP reading performance changes over time while the reading speed remains static. In this paper, we evaluate pupil dilation as a physiological metric to assess the mental workload of readers in real-time. We assess mental workload under different background lighting and RSVP presentation speeds to estimate the optimal color that discriminates the pupil diameter varying RSVP presentation speeds. We discovered that a gray background provides the best contrast for reading at various presentation speeds. Then, we conducted a second study to evaluate the classification accuracy of mental workload for different presentation speeds. We find that pupil dilation relates to mental workload when reading with RSVP. We discuss how pupil dilation can be used to adapt the RSVP speed in future VR applications to optimize information intake.

Lossy Image Compression with Stochastic Quantization

Introduction. Lossy image compression algorithms play a crucial role in various domains, including graphics, and image processing. As image information density increases, so do the resources required for processing and transmission. One of the most prominent approaches to address this challenge is color quantization, proposed by Orchard et al. (1991). This technique optimally maps each pixel of an image to a color from a limited palette, maintaining image resolution while significantly reducing information content. Color quantization can be interpreted as a clustering problem (Krishna et al. (1997), Wan (2019)), where image pixels are represented in a three-dimensional space, with each axis corresponding to the intensity of an RGB channel. The purpose of the paper. Scaling of traditional algorithms like K-Means can be challenging for large data, such as modern images with millions of colors. This paper reframes color quantization as a three-dimensional stochastic transportation problem between the set of image pixels and an optimal color palette, where the number of colors is a predefined hyperparameter. We employ Stochastic Quantization (SQ) with a seeding technique proposed by Arthur et al. (2007) to enhance the scalability of color quantization. This method introduces a probabilistic element to the quantization process, potentially improving efficiency and adaptability to diverse image characteristics. Results. To demonstrate the efficiency of our approach, we present experimental results using images from the ImageNet dataset. These experiments illustrate the performance of our Stochastic Quantization method in terms of compression quality, computational efficiency, and scalability compared to traditional color quantization techniques. Conclusions. This study introduces a scalable algorithm for solving the color quantization problem without memory constraints, demonstrating its efficiency on a subset of images from the ImageNet dataset. The convergence speed of the algorithm can be further enhanced by modifying the update rule with alternative methods to Stochastic Gradient Descent (SGD) that incorporate adaptive learning rates. Moreover, the stochastic nature of the proposed solution enables the utilization of parallelization techniques to simultaneously update the positions of multiple quants, potentially leading to significant performance improvements. This aspect of parallelization and its impact on algorithm efficiency presents a topic for future research. The proposed method not only addresses the limitations of existing color quantization techniques but also opens up new possibilities for optimizing image compression algorithms in resource-constrained environments. Keywords: non-convex optimization, stochastic optimization, stochastic quantization, color quantization, lossy compression.

On-vine drying (passérillage) improves the quality of “Hutai No. 8” table grape wine: Focusing on phenolics, aromas, color and sensory attributes

On-vine drying (passérillage) was employed for Hutai No.8 table grapes with different water loss rates and that are used for winemaking to alter the qualities of wine. Results showed that on-vine drying increased sugar content, thereby elevating alcohol and glycerol contents in the resulting wine. A moderate drying treatment (D2, 18 % water loss) produced wine with optimal red color characteristics. The D2 wine contained abundant individual phenolics such as caffeic acid, salicylic acid, resveratrol, p-coumaric acid, and proanthocyanidin B1, which exhibited strong positive correlations with color parameters (a⁎, C*ab and △E*ab). Similar trends were observed in aroma compounds, with ethyl acetate, ethyl caproate, diethyl succinate, geraniol, linalool, 4-terpinenol, α-terpineol, and β-ionone contents showing significant increment in D2, aligning with enhanced sensory evaluations of wines. Thus, improvement of wine quality can be achieved through moderate on-vine drying (18 % water loss)，serving as a valuable reference for table grape winemaking.

Characterization of hybrid silicate materials based on ceramic glazes and waste London underground dust

In “London Underground” stations, a high concentration of dust particles containing organic and inorganic matter of varying chemical composition. “London underground dust” is created from train wheels and brakes grinding against steel tracks and collected in filtration systems. The experiment will focus on using “London Underground Dust” to colour the ceramic facing tiles intended for re-use in newly built London Underground stations. The phase composition, particle size distribution surface area, morphology, and thermal behavior of collected dust were studied by XRD, XRF, SEM-EDS, BET, heating microscopy, STA-MS, UV–VIS spectroscopy. The substrate tiles for glazing experiments were prepared from local London clay. The mixtures of glazes and collected or milled dust were sprayed on the substrate tile's surface, dried and finally fired at 1060 °C. The influence of used materials weight ratio and dust milling time were shown as crucial parameters to obtain optimal final glaze colour.

Effectiveness of Papain-Based Organic Dentifrices Versus Commercial Whitening Dentifrice on Tea-Induced Tooth Stains: An In Vitro Study.

Tooth discoloration is a common issue for oral health practitioners. Whitening treatments remove surface and deep stainsusing either chemicals or over-the-counter products. Due to harmful chemical effects, organic whitening products are increasingly preferred. This study compared the effectiveness of organic papain-based dentifrices (Perfora Magic Teeth Whitening Serum, Gurugram, India) on tea stains to commercially available Colgate whitening dentifrices (Colgate-Palmolive, New York, NY). Sixty maxillary central incisors for periodontal reasons were used and divided into two groups. Each sample was soaked in freshly brewed tea for 10 minutes daily and stored in artificial saliva (Nanochemazone, Kurukshetra, India) for 24 hours. After four weeks, group 1 was treated with papain-based dentifrices, and group 2 with Colgate Visible White teeth whitening paste(CVWP) daily for four weeks. Spectrophotometric analysis (VITA Easyshade V, VITA Zahnfabrik, Bad Säckingen, Germany) was performed pre-treatment and at four weeks post-treatment. Data were compiled and statistically analyzed. Compared with group 1, group 2 exhibited an optimal color change (ΔE). Statistically significant differences were observed between the mean ΔL (lightness) and Δb (blueness -b or yellowness +b) values. CVWP showed better color achievement and stain reduction due to abrasive and peroxide components. Although Perfora Teeth Whitening Serum has low efficacy in upgrading the color of the enamel surface, it is safe for long-term use.

Effect of Different Drying Techniques on the Bioactive Compounds, Antioxidant Ability, Sensory and Volatile Flavor Compounds of Mulberry.

Mulberry perishes easily due to its high water content and thin skin. It is important to extend the shelf life of mulberry by proper processing methods. In the present study, the influence of three drying techniques, including hot air drying (HAD), vacuum drying (VD), and vacuum freeze-drying (VFD) on the quality maintenance of mulberry was comprehensively evaluated. Bioactive compounds, antioxidant activity, and the sensory and volatile flavor compounds of mulberry have been researched. The results showed that VFD treatment maintained the highest anthocyanins (6.99 mg/g), total flavones (3.18 mg/g), and soluble sugars (2.94 mg/g), and exhibited the best DPPH· (81.2%) and ABTS+· (79.9%) scavenging ability. Mulberry also presented the lowest hardness and the greatest brittleness after VFD. Additionally, VFD maintained the optimal color and presented the best sensory attributes. Furthermore, 30, 20, and 32 kinds of volatile flavor compounds were detected in HAD, VD, and VFD, respectively, among which aldehydes, esters, and ketones were the most abundant compounds. This study indicated the potential application value of VFD for the drying of fruit and vegetable foodstuffs.

Refractory organic matter removal from mature leachate by bipolar electrocoagulation-electrooxidation reactor configurations

In this study, mature leachate treatment with combined electrochemical processes was investigated to benefit from the advantages of electrocoagulation (EC) and electrooxidation (EO) simultaneously. First, control experiments were conducted, the most effective anode-cathode combination for EO was selected as Ti/IrO2-Gr, the number of Al electrodes for EC was determined as 3 and the number of Fe electrodes was determined as 5. Optimization of process parameters of the combined system with Al and Fe electrodes was conducted with Box-Behnken design (BBD). With BBD, the effect of the process parameters (initial pH, current density, and reaction time) on the system responses (COD, UV254, and color removal efficiencies) was determined. The suitability of the created model in the study was analyzed statistically and the results of quadratic models were found compatible with experimental studies. The model's capacity for prediction was also confirmed by validation experiments under optimum conditions. By implementing the optimum conditions, COD, UV254, and color removal efficiencies were determined as 71.5 %, 60.2 %, and 93.2 %, respectively for the combined process with Al electrodes and 79.5 %, 68.0 %, and 97.7 %, respectively for the combined process with Fe electrodes. Correlation of actual and predicted data showed that BBD is reliable for optimizing process parameters of combined processes with Al and Fe electrodes. The obtained results showed that combined processes are more effective than hybrid processes, based on both pollutant removal efficiencies and energy consumption.

Generic color correction for tone mapping operators in high dynamic range imaging.

One of the significant challenges in tone mapping is to preserve the perceptual quality of the tone-mapped images. Traditional tone mapping operators (TMOs) compress the luminance of high dynamic range (HDR) images with little to no consideration of image color information resulting into suboptimal colors. Existing color management algorithms require either manual parameter tuning or introducing lightness and hue shifts. The current study aimed to develop a color correction model in plausible agreement with the psychophysical phenomenon of color appearance perception for optimal color reproduction of tone mapped images. The proposed model leverages CIECAM16 perceptual correlates i.e., lightness, chroma, and hue. It is adaptive and entirely automatic while preserving the lightness of the tone-mapped image and maintaining the hue from the HDR image. Moreover, it does not require any gamut mapping correction algorithm in natural color reproduction. The effectiveness of the model was validated using objective and subjective methods. The experiments revealed that the model achieved optimal color reproduction in terms of the naturalness of the colors.

Classroom Interior Design: Wooden Furniture Prototype with Feedback from Students and Teachers

Studies indicate that natural wooden materials positively affect students’ well-being in classrooms. In addition, students spend a considerable amount of their time in classrooms predominantly seated, making school interiors a suitable place to reduce sedentary behaviors of children. A mixed team of experts in human factors, architecture, design and engineering designed a prototype wooden standing desk for indoor use and formed focus groups with students and teachers to gather feedback on the development process and to evaluate the suitability of the prototype. The prototype desk was well received by the primary school teachers and students. The students appreciated plywood as the main material for the construction of the desk; however, they criticized that the wooden tabletop should be more resistant. The height adjustability of the desk and the tiltable tabletop were the most appreciated features of the prototype. Further studies should be conducted to investigate the optimal material, shape and color of the school desk, especially the tabletop, and additional efforts should be made to design furniture that promotes a less sedentary classroom and improves students’ well-being at school.

Mixed Graph Colouring as Scheduling a Partially Ordered Set of Interruptible Multi-Processor Tasks with Integer Due Dates

We investigate relationships between scheduling problems with the bottleneck objective functions (minimising makespan or maximal lateness) and problems of optimal colourings of the mixed graphs. The investigated scheduling problems have integer durations of the multi-processor tasks (operations), integer release dates and integer due dates of the given jobs. In the studied scheduling problems, it is required to find an optimal schedule for processing the partially ordered operations, given that operation interruptions are allowed and indicated subsets of the unit-time operations must be processed simultaneously. First, we show that the input data for any considered scheduling problem can be completely determined by the corresponding mixed graph. Second, we prove that solvable scheduling problems can be reduced to problems of finding optimal colourings of corresponding mixed graphs. Third, finding an optimal colouring of the mixed graph is equivalent to the considered scheduling problem determined by the same mixed graph. Finally, due to the proven equivalence of the considered optimisation problems, most of the results that were proven for the optimal colourings of mixed graphs generate similar results for considered scheduling problems, and vice versa.