Search Results (120)

Silk fabrics and caftans preserved in the Topkapı Palace Museum collection constitute a distinguished group of cultural heritage objects reflecting the advanced weaving technologies, refined metal-thread use, and sophisticated natural dyeing practices of Ottoman court textile production. In this study, selected ceremonial caftans attributed to five Ottoman sultans were examined through a multidisciplinary and multi-analytical approach to characterize their structural, chromatic, and chemical properties. Color characteristics were evaluated in the CIE L*a*b* color space, while yarn properties, weave structures, and production techniques were investigated by optical microscopy. The morphology and elemental composition of the metal threads were analyzed using scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy (SEM–EDX), and dyestuffs were identified by high-performance liquid chromatography with diode-array detection (HPLC–DAD). The results show that compound silk weaving structures were widely used in Ottoman court textiles, metal threads were predominantly silver-based and often gold-gilded, and dyestuffs with high fastness properties were preferentially selected. The revised manuscript situates these findings within a broader international literature on historical textile analysis and natural dye characterization, while using only a limited number of directly relevant studies from the authors’ previous work. The present study therefore provides new, object-specific and comparable data for the scientific documentation, material characterization, and conservation-oriented understanding of Ottoman textile heritage. Full article

Accelerated industrial development, mass production, economic viability, and environmental sustainability impose new requirements on contemporary materials, positioning basalt as a promising, cost-effective, and abundant environmentally benign raw material. This study explores the influence of sintering temperature on the physical properties of ceramics obtained from andesite basalt aggregate. Relative density, shrinkage, and color changes were monitored to optimize the sintering temperature for the serial production of high-density ceramics. Varying the sintering temperature by 10 °C within the 1040–1080 °C range, while maintaining a constant sintering time of 60 min, leads to significant changes in relative density, shrinkage, and color. Beyond visual appearance, color changes can be quantified with coordinates in color spaces, usually in the CIELAB color space, standardized by the Commission Internationale de l’Eclairage (CIE). The best physical properties were achieved at a sintering temperature of 1060 °C for 60 min with a relative density of 99.501%, shrinkage of 12.811%, and color coordinates L*(32.03), a*(9.25), and b*(7.58) according to the CIELAB analysis. The favorable physical properties and distinctive reddish-brown color of sintered andesite basalt ceramics make them promising for floor and wall tile applications. Full article

Stain variability in digital pathology affects both cross-center diagnostic consistency and the robustness of downstream computational analysis. In this work, we formulate stain normalization as a variational inverse problem and derive a Screened Poisson Normalization (SPN) model from the steady-state reaction–diffusion mechanism underlying histological staining. In the CIE $L^{*}{a}^{*}{b}^{*}$ space, the model couples a gradient-domain fidelity term with a chromatic anchoring term, yielding a screened Poisson equation that preserves tissue morphology while enforcing color consistency. We prove that the corresponding variational problem is well-posed in $H^1\left(\mathsf{\Omega }\right)$ and stable with respect to perturbations of the input data. We further show that the screening term induces an intrinsic localization length ${𝓁}_c\sim {\lambda }_c^{-1/2}$, so that boundary perturbations decay exponentially away from tile interfaces. Based on this locality, we develop a non-overlapping tiled DCT-based spectral solver for gigapixel whole-slide images, enabling consistent tile-wise stain normalization and seamless whole-slide reassembly without heuristic boundary blending. Experiments on multi-scanner, multi-protocol, and archival-fading pathology datasets show that SPN achieves stable stain normalization with competitive chromatic alignment and strong preservation of diagnostically relevant microstructure, particularly in full-slide and tiled reconstruction settings. Supplementary experiments on synthetic pathology-like images further support the robustness of SPN under controlled color perturbations and indicate good generalization across diverse staining variations. Full article

This work analyses the influence of hydrothermal treatment (steaming) on the color stability and photochemical degradation of beech wood (Fagus sylvatica L.) with false heartwood under the influence of UV radiation. Samples in the native state and after steaming at temperatures of 105 °C (Mode I) and 120 °C (Mode II) were exposed to simulated aging in a Xenotest device for 360 h. Color changes were assessed in the color space CIE L*a*b* and surface chemical changes using ATR-FTIR spectroscopy. The results showed that unsteamed wood darkens significantly under the influence of UV radiation (ΔL* = −10.2), while wood steamed at 120 °C shows the opposite trend—lightening (ΔL* = +8.8). The color difference ΔE* reached values of 12 to 16 units for unsteamed wood, which indicates a complete color change. Steaming at higher temperatures successfully homogenizes the color of the sapwood and false heartwood and ensures their subsequent uniform visual aging. Full article

Spent coffee grounds (SCGs) and lignin-derived binders, such as ammonium lignosulfonate (ALS), are increasingly being explored as renewable resources to reduce reliance on conventional formaldehyde-based resins in wood-fiber biocomposites. Although prior work has shown that SCG–ALS adhesive systems can achieve promising mechanical performance, two practical aspects essential for industrial applications and circular design remain insufficiently explored: a predictable and reproducible visual appearance and credible end-of-life options. In this study, sustainable wood-fiber biocomposites bonded with SCG and ALS were assessed from an aesthetic performance and end-of-life perspective. Color was quantified in the CIE L*a*b* (CIELAB) space and expressed as total color difference (ΔE*) relative to a reference panel. Increasing total SCG + ALS content from 40 to 75 wt.% based on oven-dry fibers produced pronounced darkening, with lightness decreasing from L* = 47.1 to 34.3 and ΔE* increasing from 18.38 to 32.51. Short-term composting behavior was explored by embedding fragments from formulations with 40–60 wt.% total SCG + ALS (based on oven-dry fibers; equal SCG/ALS shares) into a mixed organic substrate adjusted to an initial C/N ≈ 30 and monitored for 30 days in pots and trays. The process remained predominantly mesophilic (≈14–22 °C); nevertheless, visible microbial colonization and progressive surface degradation were observed, indicating susceptibility to biological activity under moist, nutrient-rich conditions. Overall, the results show that SCG–ALS content strongly governs the visual identity of the biocomposites and suggest composting-oriented routes as a potential end-of-life direction at an exploratory level, while highlighting the need for standardized compostability assessment and longer-term monitoring to substantiate circularity claims. Full article

Accurate color property measurements are critical for advancing artificial vision in real-time industrial applications. RGB imaging remains highly applicable and widely used due to its practicality, accessibility, and high spatial resolution. However, significant uncertainties in extracting chromatic information highlight the need to define when conventional digital images can reliably provide accurate color data. This work simultaneously compares six chromatic properties across 700 Pantone^® TCX fabric samples, using optical data acquired simultaneously from both hyperspectral (HSI) and digital (RGB) cameras. The results indicate that the accurate interpretation of optical information from RGB (sRGB and REC2020) images is significantly influenced by lightness ($L^{*}$) values. Samples with bright and unsaturated colors ($L^{*}>$ 50) reach ratio-to-performance-deviation (RPD) values above 2.5 for four properties ($L^{*}, a^{*}, b^{*}$ $h_{ab}$), indicating a good correlation between HSI and RGB information. Absolute color difference comparisons (${∆E}_a$) between HSI and RGB images yield values exceeding 5.5 units for red-yellow-green samples and up to 9.0 units for blue and purple tones. In contrast, relative color differences (${∆E}_r$) comparisons show a significant decrease, with values falling below 3.0 for all lightness values, indicating the practical equivalence of both methodologies according to the Two One-Sided Test (TOST) statistical analysis. These results confirm that RGB imagery achieves reliable color consistency when evaluated against a practical reference. Full article

Paeonia delavayi displays exceptionally diverse flower colors. This study established a quantitative classification system for these colors and analyzed the relationships among pigment composition, content, and geographical distribution, providing a scientific basis for genetic diversity conservation and ornamental peony breeding. Petals from 465 plants across 30 wild populations and nurseries in central and northwestern Yunnan, China, were analyzed. Color values were quantified using CIE-Lab and Munsell color systems, while pigment content was determined using HPLC and spectrophotometry. Correlations between color values, pigments, and environmental factors were examined. The results were as follows: (1) Flower colors were classified into nine color series, each with distinct boundaries in the color value space: white (W), yellow (Y), yellow-green (YG), orange (O), orange-brown (OB), pink (P), red (R), purple-red (PR), and dark purple (DP). (2) Color values showed wide variation (a*: −23.10–65.54; b*: −4.11–94.26), indicating high diversity. (3) Yellow-category petals had high b* values (24.91–94.26), correlated with carotenoid, chlorophyll, and flavonoid content, and lacked anthocyanins. The lightness value (L*) of red-category petals was correlated with total flavonoid (TF) and total anthocyanin (ACN) content. (4) Correlation analysis showed that the formation of dark-flower colors (DP, PR, R) was significantly and positively correlated with high altitude, high soil organic carbon (SOC), and high soil total nitrogen (STN) content. The distribution of yellow-series flower colors (Y, YG) was correlated with lower altitude and weaker UV radiation, while increasing mean annual temperature (MAT) limited their distribution. (5) Analysis incorporating environmental factors showed that high-altitude areas in northwestern Yunnan, such as Shangri-La and Lijiang, had the richest flower color diversity, whereas central Yunnan’s low-altitude areas were dominated by yellow flower colors. This study indicates that the high-altitude areas of northwestern Yunnan represent the region with the richest flower color diversity in P. delavayi, and are important for the conservation of its flower color genetic diversity and as a source of genetic diversity in flower color in ornamental cultivar breeding. Full article

An anthraquinone chromophore displaying a vivid violet color in solution was synthesized and it was thoroughly characterized both spectroscopically and electrochemically, along with its X-ray crystallography. Single crystal X-ray analysis of the chromophore revealed a nearly planar π-conjugated framework with short intermolecular contacts. Cyclic voltammetry revealed two consecutive one-electron reductions, corresponding to the formation of its radical anion and dianion. The spectroelectrochemistry of the chromophore confirmed two distinct and reversible color changes with the stepwise electrochemical reduction. These were quantified via the CIE L a* b* color space. Large optical differences (98%) between the bleached and colored states were observed along with a coloration efficiency of 698 cm²/C. These parameters confirm the anthraquinone is an ideal electrochrome: capable of reversibly switching its colors with applied potential. The three color changes and color bleaching associated with the neutral, radical anion, dianion, and cation, respectively, are also of interest for extending the palette of colors of molecular electrochromes toward panchromatic color tuning with molecular structure for use in smart windows and displays. Full article

The observed growth of the global population and concern for the natural environment require the supply of inexpensive food with a low-carbon footprint. These requirements can be met, among others, by insect-derived raw materials, such as insect powders commonly referred to as flours. The aim of this study was to compare and assess the effects of four-month storage of insect powders (cricket, mealworm) and cereal flours (millet, oat, rice) under conditions similar to household storage (room temperature, partially emptied packages) on selected quality characteristics. It was assumed that, due to their different protein–fat composition and high degree of comminution, insect powders may exhibit a different dynamic of changes compared to flours in which starch is the dominant matrix. The scope of the research included the assessment of moisture content, acidity, ash content and total protein content, analysis of the amino acid profile, color parameters in the CIE L*a*b* space, changes in volatile compounds, and determination of heavy metal content (Cd, Pb, Hg, As). The obtained results enabled a comprehensive characterization of the quality stability and nutritional value of the tested raw materials after the storage period. The analyses revealed clear differences between cereal flours and insect powders, resulting from differences in chemical composition and production technology. Insect powders were characterized by a higher protein content and a more favorable amino acid profile compared to cereal flours. In addition, they exhibited lower moisture content, different color, and a distinct aroma profile, which can be attributed both to their production technology and to a higher proportion of hydrophobic components. It was shown that during storage the amino acid composition of the tested flours remained relatively stable, as did color; however, mealworm powder exhibited the lowest color stability. It was also demonstrated that cereal flours are characterized by a greater capacity for water sorption, which is related to their starch matrix, whereas insect powders undergo processes related to lipid degradation, leading to increased acidity and changes in the profile of volatile compounds. Certain safety concerns may arise from the exceeded permissible cadmium content observed in mealworm powder. Full article

The external color of smoked sausages is a critical indicator of quality and uniformity in processing. Commercial colorimeters are unsuitable for high-throughput sorting due to the challenges posed by the sausage’s curved cylindrical surface and the need for an inline application. This study introduces a novel non-contact sensing module (LEDs at 45°, fiber optic collection at 0°) to acquire spectral data (400–700 nm) and derive CIE LAB. First, a handheld prototype validated the accuracy of the sensing module against a benchtop spectrophotometer. It successfully categorized five color grades (‘Over light’, ‘Light’, ‘Standard’, ‘Dark’, and ‘Over dark’) with a clear distribution on the a*-L* diagram. This established acceptable color boundary conditions (44.2 < L* ≤ 61.3, 14.1 < a* < 23.9). Second, three sensing modules were integrated around a conveyor belt at 120° intervals, forming the core of an automated inline sorting system. Blind field tests (n = 150) achieved high sorting accuracies of 95.3–97.3% with an efficient inspection time of less than 2 s per sausage. This work realizes the standardization, digitalization, and automation of food color inspection, demonstrating strong potential for smart manufacturing in the processed meat industry. Full article

This study presents a field-oriented AI web system for durian orchard management that recognizes leaf health from on-orchard images under variable illumination. Two complementary pipelines are employed: (1) a rule-based module operating in HSV and CIE Lab color spaces that suppresses sun-induced specular highlights via V/L* thresholds and applies interpretable hue–chromaticity rules with spatial constraints; and (2) a Deep Feature (PCA–SVM) pipeline that extracts features from pretrained ResNet50 and DenseNet201 models, performs dimensionality reduction using Principal Component Analysis, and classifies samples into three agronomic classes: healthy, leaf-spot, and leaf-blight. This hybrid architecture enhances transparency for growers while remaining robust to illumination variations and background clutter typical of on-farm imaging. Preliminary on-farm experiments under real-world field conditions achieved approximately 80% classification accuracy, whereas controlled evaluations using curated test sets showed substantially higher performance for the Deep Features and Ensemble model, with accuracy reaching 0.97–0.99. The web interface supports near-real-time image uploads, annotated visual overlays, and Thai-language outputs. Usability testing with thirty participants indicated very high satisfaction (mean 4.83, SD 0.34). The proposed system serves as both an instructional demonstrator for explainable AI-based image analysis and a practical decision-support tool for digital horticultural monitoring. Full article

Background/Objectives: This study aimed to perform a comparative analysis of the original Viagra^® product and sildenafil-containing tablets obtained from illegal sources (the darknet). Specifically, the analyzed material consisted of samples seized by Polish law enforcement authorities from unverified vendors operating within the Central European darknet market. The study utilized thermal methods, specifically Thermogravimetry (TG), Derivative Thermogravimetry (DTG), and calculated Differential Thermal Analysis (c-DTA), as well as colorimetric analysis based on the International Commission on Illumination (CIE) L*a*b* system. Methods: Thermal analyses enabled the assessment of the thermal stability of the tested samples, identification of characteristic stages of thermal decomposition, and determination of differences in thermal behavior between the pure substance, the original preparation, and darknet samples. In turn, color measurements in the CIE L*a*b* space allowed for an objective comparison of tablet appearance and determination of the degree of color similarity to the original product. Results: The obtained results showed that only a few samples (V1, V3, V4, V6, V8) exhibited features similar to the original Viagra^®, both in terms of thermal profile and color. Most of the tested tablets were characterized by significant variability in physicochemical properties, indicating a lack of quality control and inconsistency in formulation. Samples V2 and V7 deviated particularly strongly—both thermally and visually—suggesting that they might not contain the original active substance or contained it in a different chemical form. Conclusions: The use of combined thermal and colorimetric methods proved to be an effective tool in the identification of counterfeit pharmaceutical products, enabling simultaneous evaluation of their composition and authenticity. The results confirm the validity of employing integrated physicochemical analyses for the detection of falsified medicines present on the illegal market. Full article

The analysis of the physical and chemical properties of blackcurrant (Ribes nigrum L.), strawberry (Fragaria ananassa Duchesne ex Weston) and raspberry (Rubus idaeus L.) seeds recovered from pomace—food processing waste—was carried out. The weight of the one thousand seeds, their dry weight, swelling properties, and color in the CIE L*a*b* space, as well as the percentage of basic chemical components, i.e., protein, carbohydrate (including total dietary fiber, insoluble fiber, and soluble dietary fiber), fat, and ash were determined. Polyphenols content and antioxidant activity was determined. In addition, the amounts of individual phenolic compounds, fatty acids, and amino acids, as well as macro and micro-nutrients, were identified and analyzed. The potential usefulness of raspberry seeds as a rheology modifier of cosmetics and food products was estimated due to the high content of mucilage and swelling index similar to linseed and a favorable color with a high value of the b* parameter (22.1) corresponding to yellow color simultaneously with high luminescence (L* = 59.4). Oils obtained from all tested seeds are potentially useful in cosmetic preparations due to the high content of n-6 acids (50.4–71.5%), and oils from strawberry and raspberry seeds as a result of containing n-3 acids, respectively; 30.5–32.3% may be beneficial for dietary supplementation. In addition, the dietary values of the tested seeds are emphasized by the high content of dietary fiber (53.1–63.1%), antioxidant properties (the highest for blackcurrant) and the presence of phenolic compounds such as procyanidin derivatives, catechins (raspberry), quercetins and kaempferols (blackcurrant), and pelargonidin (strawberry). Full article

Lapis lazuli is a valued gemstone that displays a wide spectrum of blue hues, yet the quantitative link between its color and internal sulfur speciation remains unresolved. This study integrates colorimetry with electron probe microanalysis and UV-Vis, Raman, and X-ray photoelectron spectroscopy to establish this relationship and build a robust grading framework within the CIE 1976 L*a*b* color space. X-ray diffraction was employed to determine the mineral composition and confirm that the chromogenic elements originated from lazurite. K-means clustering with Fisher’s discriminant validation classifies samples into four grades: Fancy Blue, Fancy Intense Blue, Fancy Deep Blue, and Fancy Dark Blue. Multimodal analyses identify three sulfur species—[S₃]^·−, S²⁻, and ${\mathrm{SO}}_4^{2-}$—and show that higher sulfur content correlates with lower lightness, reduced chroma, and a violetish-blue shift. [S₃]^·− is confirmed as the dominant chromophore, producing the strong 600 nm absorption that defines the blue hue. A weak absorption band observed near 400 nm in some samples can be attributed to S²⁻ and ${\mathrm{SO}}_4^{2-}$ species, but no visually perceptible effect of this band on the overall color was detected. Full article

The aim of this study was to evaluate selected parameters during storage of wheat bread enriched with hazelnut oil cake (HOC) or walnut oil cake (WOC) at levels of 5%, 10%, and 15%. Bread volume and specific volume, chemical composition, crumb moisture, crumb color in the CIE L*a*b* space, crumb texture, total phenolic content (TPC), and antioxidant activity were determined. Tests were conducted on days 1, 3, and 7 of storage. It was found that the HOC/WOC-enriched breads had lower volume and specific volume compared to the control bread. The addition of HOC or WOC improved the nutritional value of the bread, as they had higher protein, mineral, and dietary fiber contents and lower carbohydrate levels. Crumb moisture decreased during storage. The addition of HOC or WOC to the recipe increased crumb hardness while reducing elasticity and cohesiveness. During storage, an increase in hardness, a decrease in elasticity and cohesiveness, and a darker crumb were observed. The enriched breads were characterized by significantly higher TPC and AA contents, and the values of these parameters increased with the addition of nut oil cake. However, the TPC decreased significantly during storage. Full article