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Abstract Background Effects 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. Methods Ceramic 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. Results An 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

The utilization of plasma treatment as a technique for fading the colours on textiles is an environmentally friendly approach. However, the challenge lies in the continuous adjustment of its parameters to attain desired fading colour effects. This is due to the unclear mechanism causing changes in fading effect as a result of alterations in plasma treatment parameters. This research endeavours to predict the alteration of fading effect after plasma treatment of cotton fabrics under varying parameters through the development of a prediction system based on a Bayesian Regulated Neural Network (BRNN) with 10-fold cross-validation. Through a modular approach, the inputs for the training of BRNN models include initial values of plasma treatment parameters such as colour depth, air (oxygen) concentration, water content, treatment time, and one of the CIE L*a*b* values and K/S values corresponding to cotton materials. The outputs, trained individually by four independent BRNN models, are the final values of four colour variables: CIE L*, CIE a*, CIE b* and K/S. The models were trained and validated through the Bayesian Regularization Algorithm and 10-fold cross-validation on 192 data sets, yielding fitted coefficients of determination R2 of 0.9956, 0.9976, 0.9980 and 0.9687, respectively. Approximately 87.5% − 91.67% of predicted colours were within the range of imperceptible or acceptable differences from actual colours. Hence, the developed artificial intelligence system can aid textile finishers in adjusting the plasma colour fading machine's parameter settings and selected recipes, thus enhancing efficiency and reducing cost and trial time. [ABSTRACT FROM AUTHOR]

Background: Effects 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. Methods: Ceramic 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. Results: An 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). Conclusions: The colour reproduction ability of lithium disilicate glass-ceramics is significantly affected by their translucency, layer thickness, and 7 substrates out of 9 substrates examined. [ABSTRACT FROM AUTHOR]

Graffiti, by their very nature, are ephemeral, sometimes even vanishing before creators finish them. This transience is part of graffiti's allure yet signifies the continuous loss of this often disputed form of cultural heritage. To counteract this, graffiti documentation efforts have steadily increased over the past decade. One of the primary challenges in any documentation endeavour is identifying and recording new creations. Image‐based change detection can greatly help in this process, effectuating more comprehensive documentation, less biased digital safeguarding and improved understanding of graffiti. This paper introduces a novel and largely automated image‐based graffiti change detection method. The methodology uses an incremental structure‐from‐motion approach and synthetic cameras to generate co‐registered graffiti images from different areas. These synthetic images are fed into a hybrid change detection pipeline combining a new pixel‐based change detection method with a feature‐based one. The approach was tested on a large and publicly available reference dataset captured along the Donaukanal (Eng. Danube Canal), one of Vienna's graffiti hotspots. With a precision of 87% and a recall of 77%, the results reveal that the proposed change detection workflow can indicate newly added graffiti in a monitored graffiti‐scape, thus supporting a more comprehensive graffiti documentation. [ABSTRACT FROM AUTHOR]

This paper aims to examine the influence of the colour of textile materials on the speed of colour change of a screen-printed sample using a reversible thermochromic ink, focusing on application in the sports industry. In other words, what effect the colour of textile materials has on the optical properties of the printed sample during its cooling. Two different types of textile materials of different colours were used as a substrate for printing, and a water-based magenta leuco thermochromic ink with an activation temperature of 31 °C was used for screen printing. Experimental results indicate significant differences in the speed and intensity of colour change between different colours of textile substrates. It has been found that darker substrate colours tend to provide a slower and less intense colour change of the printed pattern compared to lighter substrate colours. These studies are essential for textile designers and sportswear manufacturers to understand better the factors that influence the speed and intensity of colour change due to monitoring the physical and physiological state of the athlete.

It is known that gloss has a significant impact on colour measurement. The UV varnish used for surface finishing, spot effects, as well as special effects, such as 3D effects and formation of Braille, has a pronounced gloss effect. In this work, a comparison of the spectrophotometer measurement geometry influence on the colour measurement of an unprinted PVC sample covered with UV varnish was done. UV varnish was applied successively in layers, and patches with different number of varnish layers, from 1 to 12, were formed. Two spectrophotometers with different measurement geometries were used for the measurement: Konica Minolta CM-2600d with d/8 measurement geometry, with spectral reflection included and excluded, and different measurement aperture 3 and 8 mm, and X-Rite eXact with 45/0 measurement geometry. By comparing the measurements, it was established that there is a significant difference in the measured values between different measuring device geometries on the given samples, and that the number of UV varnish layers has a significant influence on this difference.

Addressing fabric fading in the textile industry, this research investigates plasma treatments as a sustainable solution. The ambiguous relationship between plasma parameters such as air concentration, moisture content, and treatment duration with fading introduces uncertainty in the treatment process, necessitating optimization through precise prediction. Such precision not only curtails costs but also highlights the pivotal role of digital innovations in textile fabrication. Two predictive systems, Bayesian Regulated Neural Network (BRNN) and Gaussian Process Regression (GPR), were developed using tenfold cross-validation to accurately link these parameters to fading results. To handle prediction complexity and small samples, a modular approach was adopted. Four individual BRNN and GPR models predicted CIE L*, a*, b*, and K/S values and were integrated into a single system. The systems' predictive capabilities were compared, revealing that GPR's predictive accuracy generally surpassed that of the BRNN model, although its advantage lessened in the testing set, particularly for CIE a* predictions. Nevertheless, it is noteworthy that both GPR and BRNN models demonstrated significant prediction performance on the unseen dataset, with the colour prediction deviating from the actual colour within an acceptable range for industrial applications in most scenarios. Specifically, under a stricter standard of ∆E < 1, the GPR model's predictive accuracy was able to maintain between 79.17 and 87.5%. Thus, the application of the BRNN and GPR models might provide valuable digitalization insights for cotton processing, saving time and cost while efficiently predicting fading effects. [ABSTRACT FROM AUTHOR]

It is known that gloss has a significant impact on colour measurement. The UV varnish used for surface finishing, spot effects, as well as special effects, such as 3D effects and formation of Braille, has a pronounced gloss effect. In this work, a comparison of the spectrophotometer measurement geometry influence on the colour measurement of an unprinted PVC sample covered with UV varnish was done. UV varnish was applied successively in layers, and patches with different number of varnish layers, from 1 to 12, were formed. Two spectrophotometers with different measurement geometries were used for the measurement: Konica Minolta CM-2600d with d/8 measurement geometry, with spectral reflection included and excluded, and different measurement aperture 3 and 8 mm, and X-Rite eXact with 45/0 measurement geometry. By comparing the measurements, it was established that there is a significant difference in the measured values between different measuring device geometries on the given samples, and that the number of UV varnish layers has a significant influence on this difference. [ABSTRACT FROM AUTHOR]

With the application of bleaching treatments, the color of the wood material changes. When different bleaching agents are applied to the same wood, different results are likely to be obtained. In this study, wood species doussié (Afzelia africana), iatandza (Albizia ferruginea), merbau (Intsia bijuga (Colebr.) O. Kuntze), mahogany (Swietenia mahagoni L.), and hornbeam (Carpinus betulus L.) along with one and two component (B-One-C and B-Two-C) wood bleaching chemicals were applied to the wood material surfaces with sponge technique. Then, color parameters (ho: hue angle, a*: red color tone, b*: yellow color tone, C*: chroma, and L*: lightness) were determined on bleached and unbleached materials. According to the results obtained, B-One-C application increased ho, a*, b*, C*, and L* values in all wood species. The highest ∆E* values were determined in mahogany, doussié, hornbeam, and merbau wood species treated with B-Two-C. The chemicals used in the study showed different results on the same wood.

With the application of bleaching treatments, the color of the wood material changes. When different bleaching agents are applied to the same wood, different results are likely to be obtained. In this study, wood species doussié (Afzelia africana), iatandza (Albizia ferruginea), merbau (Intsia bijuga (Colebr.) O. Kuntze), mahogany (Swietenia mahagoni L.), and hornbeam (Carpinus betulus L.) along with one and two component (BOne- C and B-Two-C) wood bleaching chemicals were applied to the wood material surfaces with sponge technique. Then, color parameters (ho: hue angle, a*: red color tone, b*: yellow color tone, C*: chroma, and L*: lightness) were determined on bleached and unbleached materials. According to the results obtained, B-One-C application increased ho, a*, b*, C*, and L* values in all wood species. The highest ΔE* values were determined in mahogany, doussié, hornbeam, and merbau wood species treated with B-Two-C. The chemicals used in the study showed different results on the same wood. [ABSTRACT FROM AUTHOR]

The paper is devoted to the study of the optical indexes of UV inkjet imprints on polymeric materials. The appearance of new types of polymeric materials with different textures and colours, on the one hand, helps to expand the range of souvenir, advertising and gift products, and on the other hand, there is a need to provide accurate colour reproduction on different surfaces. An actual task is to ensure accurate reproduction of the corporate colour when branding business products, making advertising and souvenirs on various materials, which will contribute to the recognition of companies. The paper analyses the regulatory documents that guide the production and quality control of digital imprints. It has been found, that the assessment of colour reproduction accuracy requires a comprehensive approach and includes: selecting a reference for comparison; establishing the level of required reproduction accuracy (A, B and C); taking into account the viewing distance of imprints. Based on the results of the study, it was found, that the colour of the printed material has a critical impact on the chromaticity of colour. It was found, that the application of a white substrate in one layer allows for reducing the colour difference on the coloured samples, but is insufficient for accurate colour reproduction. The study found, that the misalignment of the ink layers is 0.12 mm, which is generally within specification tolerances, but the imprints show a white outline visible to the naked eye. A visual assessment of the corporate colour under study revealed contamination with another ink, mainly magenta; the paper presents possible causes of the detected contamination. Based on the research results, it can be concluded, that determining the influence of the properties of printed materials on the optical indexes of imprints will allow manufacturers to adjust their technological processes in order to obtain products of the predicted quality.

A palette composed of multiple colour patches can express lots of information. This study aimed to explore the factors that influenced colour palette preference, including colour attributes and colour differences between colour patches. A new attribute called Delta_Order for calculating the colour difference of a palette was presented, which fully considered the colour difference and the placement. In order to comprehend colour palette preference intuitively, a prediction model of palette preference was proposed based on lightness, chroma and the new metric Delta_Order. Two psychophysical experiments including analyzing and validating experiments were conducted. Fifty observers were invited to evaluate the colour palette preference. The results indicated that lightness played an important role in colour preference, but colour preference was not related to hue angle. For Delta_Order, there was a significant negative correlation between the new metric and preference score since the Pearson correlation coefficient was −0.801. This meant that observers preferred the palettes with low Delta_Orders. According to the validating test, it confirmed that the proposed prediction model had a good stability. The predicted trends were consistent with the true results, and the scores were similar to each other. These analysis results had a certain guiding significance in design and industry about colour.

Earthen sites with important historical, cultural, artistic, social, and scientific values have been seriously damaged. Basal erosion, which is caused by soluble salts, water runoff, and sand-driving wind, is an extremely threatening erosion pattern for earthen sites. A cushion layer which has a damp-proofing function and good physical and mechanical properties can effectively decrease basal erosion. The primary aim of this study is to investigate material selection for the hydrophobic cushion layer for earthen sites in northwest China. The results indicate that cooked tung oil and sticky rice liquid, traditionally used in China, cannot meet the fundamental requirements of sufficient hydrophobicity for the cushion layer. Although polyvinyl alcohol (PVA) solution and tung oil exhibit similar properties in terms of soil hydrophobicity, water vapour permeability, water resistance, surface hardness, and colour difference for samples with 0.0-1.0% content, the PVA solution is significantly better than tung oil in unconfined compressive strength, deformation modulus, wave velocity, and viscosity. Therefore, the PVA solution should be preferentially selected as a hydrophobic cushion layer material according to the results of this work. When the mixing method is adopted, 0.6-1.0% PVA content is the best choice. [ABSTRACT FROM AUTHOR]

Alder wood (Alnus glutinosa L.) was steamed with a saturated steam-air mixture at a temperature of t = 95 °C, or saturated steam at t = 115 °C and t = 135 °C to obtain a pale brown colour, a light red-brown colour and a dark brown-grey colour. Subsequently, samples of unsteamed and steamed alder wood were irradiated with a UV lamp in a Xenotest Q-SUN Xe-3-HS after drying in order to test the colour stability of steamed alder wood. The colour change of the wood surface was evaluated by means of measured values on the coordinates of the colour space CIE L*a*b*. The results show that the surface of unsteamed alder wood as well as steamed alder wood with a steam-air mixture at t = 95 °C and saturated steam at t = 115 °C darkened and browned due to photochemical reactions caused by UV radiation. The opposite tendency was recorded at the surface of alder wood steamed with saturated steam with a temperature of t = 135 °C, where the deep dark-brown-grey colour lightened to a brown-reddish colour shade under the influence of UV radiation. The analysis of the changes in the coordinates of the colour space CIE L*a*b* shows that the greater the darkening and browning of the alder wood by steaming, the smaller the changes in the values of ΔL*, Δa*, Δb* of the steamed alder wood caused by UV radiation. The positive effect of steaming on UV resistance is evidenced by the decrease in the overall colour difference ΔE*. While the value of the total colour difference of unsteamed alder wood caused by UV radiation is ΔE* = 10.9, it decreased to ΔE* = 8.7 for alder wood steamed with steam-air mixture at t = 95 °C, which is a decrease of 20.2 %; for alder wood steamed at t = 115 °C it decreased to ΔE* = 6.5, which is a decrease of 40.3 %; and for alder wood steamed with saturated water steam with the temperature t = 135 °C it decreased to ΔE* = 5.7, which is a decrease of 47.7 %.

• Lightness evaluation in specimens treated with TiO 2 in the long term. • TiO 2 effect on light radiation of coating mortars. • Aesthetic perception maintenance of facades treated with TiO 2. • Solar absorption on surfaces treated with TiO 2. • The color difference on surfaces treated by TiO 2. The importance of colours is not limited to the aesthetic but also other parameters like thermal comfort. Painting light colours on the building's external surfaces increases its reflection of solar radiation, reducing the heat gains. In contrast, dark colours can increase solar heat gains by absorbing more radiation. Regarding the TiO 2 answer to the lightness on the facade, different samples of TiO 2 were tested. First, in the laboratory for methylene blue dye degradation and second in a natural environment using different forms of treatment (powder and suspension) on mortars, measured by a spectrophotometer over three years to determine the loss of lightness over time. The methylene blue test showed that the TiO 2 -P25p, TiO 2 -PC-S7s, and TiO 2 -E502s samples had the same effectiveness after exposure to artificial UV radiation, while the TiO 2 -PC105p sample presented the worst performance. Concerning the lightness, after thirty-seven months of the natural exposition, the white painted specimens had the best results than specimens with TiO 2 suspensions and specimens with TiO 2 in powder. Beyond the absorptivity, the white painted specimens could be considered with low absorptivity. In contrast, the specimens treated with TiO 2 suspension and those treated with TiO 2 powder could be medium absorptivity. Regarding the visual aesthetic perception, the study concludes that for the final user, there is no great difference in white painted specimens, while for the other (powder and suspension), the colour difference can be noticed well over three years of exposure. [ABSTRACT FROM AUTHOR]

Objectives: To proof the feasibility of direct colour printing on 3Y-TZP using 222 nm UV-C through investigating the degree and durability of the colour changes, and testifying whether surface, mechanical and biological properties are influenced by the treatment., Methods: 222 nm UV-C light (Irradiance: 1.870 mW/cm 2 ) was used to treat 3Y-TZP for durations from 15 min to 24 h. ΔE*, TP, crystalline structure, surface morphology, S a , BFS and biological activities were investigated before and after irradiation. SPSS 28.0 was used for statistical analysis (α = 0.05)., Results: 222 nm UV-C irradiation was capable to shade white 3Y-TZP into tooth colours. With the increase of ΔE*, TP decreased, such that the longer the irradiation time, the higher the ΔE* (logarithmic relationship) and lower the TP. Despite the induced optical changes being prone to fade, the process can be predicted by inversely proportional relationships between ΔE*, TP and the testing points. The treated surface exhibited enhanced hydrophilicity, while the recovery phenomenon was observed. Other properties were not altered by the treatment., Significance: This is the seminal study demonstrating the feasibility of direct colour printing on 3Y-TZP using 222 nm UV-C. The new relationship between the colour centre and E g of 3Y-TZP was established, whereas the induced optical changes were stabilised after a certain period and were highly predictable by controlling the irradiation periods. The irradiation was only correlated to the electron excitation and oxygen vacancies, and would not lead to any changes of other properties. A simple, safe and promising approach to achieve satisfactory colours on 3Y-TZP in clinical practice can be developed., Competing Interests: Declaration of Competing Interest There are no known conflicts of interest associated with this publication and there has been no significant financial support for this work that could have influenced its outcome., (Copyright © 2024 Elsevier Inc. All rights reserved.)

Copyright of Wood Industry / Drvna Industrija is the property of Drvna Industrija and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Ageing of historical documents often results in changes in the optical properties of the constituent materials. Imaging spectroscopy (IS) can be a valuable tool for monitoring of such changes, if the method fulfils two important conditions. Firstly, compared to natural ageing, the accumulated light dose from repeated measurements of the monitored document must not induce any significant degradation. Secondly, the monitoring instrumentation and procedures should be sensitive enough to detect changes in the materials before they become visible. We present experimental methods to evaluate the suitability of IS instrumentation for monitoring purposes. In the first set of experiments, the impact of repeated monitoring measurements was determined using a set of Blue Wool Standard materials. In the second set of experiments, the capability of the instrument to detect spectral changes was tested using ISO standard materials and several documents representative of European archive collections. It is concluded that the tested hyperspectral instrument is suitable for monitoring of the colour change of documents during display. The described experimental approach can be recommended to test the suitability of other imaging spectroscopy instruments for monitoring applications.

The paper deals with the effect of the coating film thickness of various types of coating material on the quality of surface finish on lightweight plywood. Three surface finishes (solvent-based, water-based and hard wax) were formed of coating materials on the lightweight plywood sheathed with pressed beech veneer. The coating materials were applied in one, two and three layers. The surface finished samples were exposed to simulated light radiation in the Q-SUN test. Several optical surface properties (gloss value, colour difference, surface roughness) and resistance surface properties (impact resistance, abrasion resistance) were investigated. The optical properties of all surface finishes were very much allied to the type of coating material and the coating film thickness. As the coating film thickness (i.e., the number of coats) increased, the gloss increased as well. Evaluated dependences of gloss value and of colour difference on the coating film thickness showed a high degree of dependence on the Solvent-based and Water-based surface finishes. For the Hard wax surface finish, the evaluated dependence of gloss value on the coating film thickness showed a very high degree of dependence. The surface roughness was very much allied to the type of coating material and the wood fibre direction. The lowest surface roughness of the surface with three layers was noticed on hard wax. The mechanical resistance properties of all surface finishes were very much allied to the type of coating material and the coating film thickness. Evaluated dependence of impact resistance on the coating film thickness showed a very high degree of dependence on the Solvent-based and Water-based surface finishes, and a high degree of dependence on the Hard wax surface finish. The highest resistance to abrasion and the highest impact resistance was measured on the hard wax surface finish. [ABSTRACT FROM AUTHOR]

Colours are one of the most important factors in everyday life. The exact number of existing colours is not yet fully known. Nevertheless, people are known for having poor colour memory. The ability to remember colours depends both on the characteristics of an individual and the situation in which the colour needs to be recalled. The field of colour memory (perception and memory of unusual colours) has been very poorly researched. The aim of this study was to analyse long-term colour memory for selected associative colours, comparing it with short-term colour memory. The research approach was based on observation, with observers observing for a period of time a particular colour, image, or a descriptively given reference colour. Colour was treated separately from associations in the first part, and related to associations in the second and third parts. The first part contained all the reference colours shown independently of associations, the second part contained grayscale images of brands, and the third part comprised descriptively given colours. The result analysis showed that people remember colours very poorly. Observers generally performed better in testing short-term memory. Moreover, the way the template was presented had a noticeable effect on the long-term colour memory. When the image was given in grey, the results were better. The descriptive rendering of reference colours shown did not contribute to better results. The gender of observers did not significantly affect the results.

Copyright of Tekstilec is the property of University of Ljubljana, Faculty of Natural Sciences & Engineering, Department of Textiles and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Façade integrated photovoltaics are a promising way to employ renewable energy technology in the built environment. The colours of façade integrated photovoltaics are essential to the overall aesthetic quality of buildings, especially in urban context. Currently, several brands of coloured photovoltaics are available in the market for architects, however, unlike traditional façade materials, the colorimetric characteristics of coloured PVs are rarely studied. To provide a foundation for further aesthetic research on façade integrated photovoltaics and to develop architectural design guidelines with façade integrated photovoltaics, a series of colour angular sensitivity experiments have been carried out on six different types of opaque coloured photovoltaics. The photovoltaic samples were measured from different distances and at different angles with a PR‐655 spectroradiometer, in a series of laboratory and outdoor experiments. The experimental results show that the surface properties including colour, texture, and surface gloss have a strong impact on the photovoltaic's colour angular sensitivity. Goniochromatic phenomena have been found in samples with a spectrally selective coating technique (Kromatix photovoltaics) and samples with anti‐reflective coatings with metallic texture (LOF metallic photovoltaics). Samples with selective filter technique and low‐gloss rough finishing (ISSOL photovoltaics) show angular insensitivity for hue in different illumination conditions. Samples with mineral coating techniques (Sunage photovoltaics) show colour angular insensitivity in overcast illumination, while matt finishing leads to larger colour angular difference than gloss finishing in direct sunlight illumination. This study also proposed basic design suggestions to integrate different coloured photovoltaics according to their colour angular sensitivity characteristic from architectural perspective. [ABSTRACT FROM AUTHOR]

Three frequently used formulas and their power function modifications were used to calculate the colour differences after the exposure to light and to study the stability of ink jet prints by spectrophotometric measurements. The prints were exposed to the simulated daylight of different spectral composition at constant conditions of temperature and relative humidity. According to the results, the black prints were the least affected and the magenta prints exhibited the biggest colour differences. The most resistant have proven to be the prints on archival paper which contained no optical brightening agents. The presence of shortwave radiation between 320 and 300 nm additionally diminished the resistance of prints. The same conclusions were obtained regardless of the colour difference formula applied, with one exception. Generally, the CIEDE2000 formula performed the best, especially when comparing samples with a smaller colour difference.

In order to achieve high-quality colour prints by using an electrophotography printing machine, it is necessary to prepare the printing substrate. Additional treatment may be needed to achieve the better substrate surface tension for optimally attaching the liquid electrophotography ink to the fine art paper. To ensure good adhesion of the ink to the printing substrate, a pre-treatment by application of surface tension regulating fluids (priming) may be used. In this paper, we will determine the possibility of realization of the CMY prints and the possibility of achieving an increased range of tone value in electrophotography digital printing. Based on the results, the new possible values of reproduced CMY tones will be determined so that a higher print quality can be achieved. The application of primers changes the optical properties of the paper printing substrate, which directly affects the colour reproduction. An additional 100 % increase of primer application will result in total colour changes of ΔEC (0,5g/m2 & 1g/m2) = 0,06, ΔEM (0,5g/m2 & 1g/m2) = 0,42, ΔEY (0,5g/m2 & 1g/m2) = 0,08. In this scenario, 1 g/m2 application of primer will produce the most intense full tones and therefore the highest quality prints for all three ElectroInk process colours.

Water is the ultimate and mostly used media during textile materials processing, especially in colouration. This study investigated the possibilities of using seawater for cotton and polyester fabrics dyeing. Single jersey fabrics made of 100 percent cotton and polyester were dyed using a standard recipe and two separate water source as dyeing mediums. It has been focused on the assessment of colour fastness to wash, perspiration, saliva, rubbing, water, light and colour difference value due to compare the efficiency of dyeing media. The results revealed that the cotton fabric dyed with seawater showed lighter shade than that of ground water sample. But for polyester fabric darker shade was obtained compared to ground water. The cotton sample dyed with sea water carried about 15% higher colour strength than ground water dyed sample but for polyester it was very negligible, only 3%. Moreover, the results of colour fastness to wash, perspiration, saliva, rubbing, water and light for seawater dyed samples of cotton and polyester were shown satisfactory outcomes having the grading of 4–5 in most of the cases. This exploration established that commercial dyeing processes were robust and can be practically transferable into the seawater medium for cotton and polyester fabrics.

We studied the effect of ultrasonic activation of brine (3%) during salting on the degree of stability of colour parameters of pork with normal (NOR) and abnormal course of autolysis in the CIE Lab colour space. The mechanism of stabilisation of the colour of meat is attributed to donor–acceptor bonds of metmyoglobin (MetMb). The accumulation of excessive number of free electrons in the medium are capable of activating MetMb. This reduces the activity of meat, when the native participants of the metmyoglobin reductase system and their own antioxidant systems of meat are depleted.Based on the additive calculation of deviations (increase / decrease) by the coordinates L*, a*, b* in the CIE Lab system, and the total colour difference (ΔE) in control and experimental samples, recommendations were developed. To optimize the colour characteristics of all types of meat, both on the surface and in the thickness of the meat, the preliminary activation of a 3% brine in a low-frequency submersible ultrasonic unit is recommended. Moreover, preliminary cavitation activation of a 3% is more preferable to stabilise the colour of PSE – meat (pale, soft, exudative (watery),) brine in a flow-through installation.

Thirty-five gem-quality turquoise samples with various colours were investigated using energy-dispersive X-ray fluorescence spectroscopy, ultraviolet–visible spectroscopy, Fourier-transform infrared spectroscopy and scanning electron microscopy. Sample chemical and spectral analyses indicate that Fe3+ contributes to green hue of turquoise, whose absorption band exhibits a bathochromic shift from 426 to 428 nm with increasing V content in the solid-solution series turquoise-chalcosiderite. V3+ enhances absorption in the blue and orange regions, and Cr3+ increases absorption in the green region, both of which are responsible for the vivid greenish yellow in faustite. Substitutions of Al by medium-sized trivalent cations (primarily Fe3+ and V3+) enhance polarity of the phosphate group (PO4)3−, resulting in strong absorption in the infrared spectra for analogues of turquoise. The reflectivity ratio (ROH) of the double absorption peaks at 781 and 833 cm−1 allows faustite to be distinguished from turquoise and chalcosiderite, with a value greater than 1, while V-rich faustite only has a single absorption peak at 798 cm−1. An increasing amount of absorbed water contributes to blue chroma in turquoise and has a negative effect on lightness based on the CIE 1976 L*a*b* colour system. Loose turquoise with a low specific gravity tends to display greater colour differences with a significant decrease in lightness.

This work is concerned with the prediction of visual colour difference between pairs of palettes. In this study, the palettes contained five colours arranged in a horizontal row. A total of 95 pairs of palettes were rated for visual difference by 20 participants. The colour difference between the palettes was predicted using two algorithms, each based on one of six colour‐difference formulae. The best performance (r2 = 0.86 and STRESS = 16.9) was obtained using the minimum colour‐difference algorithm (MICDM) using the CIEDE2000 equation with a lightness weighing of 2. There was some evidence that the order (or arrangement) of the colours in the palettes was a factor affecting the visual colour differences although the MICDM algorithm does not take order into account. Application of this algorithm is intended for digital design workflows where colour palettes are generated automatically using machine learning and for comparing palettes obtained from psychophysical studies to explore, for example, the effect of culture, age, or gender on colour associations. [ABSTRACT FROM AUTHOR]

High-fidelity colour reproduction can be performed through reconstructing a spectral reflectance of an object surface. The particular branches in need of this reproduction range from colour printing to artistic fields. In order to improve the reconstruction accuracy for the spectral reflectance, we suggest a spectral-reflectance reconstruction method based on a mixed weighting (MW). This method is a combination of a number of earlier techniques, namely a Wiener estimation method and so-called methods of weighting on a group with smaller colour difference and weighting on a group with smaller spectral reflectance error. Specifically, we have obtained the spectral estimation with higher reconstruction accuracy by weighting the reconstruction spectra obtained by different methods. The weights for these methods have been selected through minimizing the colour difference. The MW method makes a full use of advantages of the underlying methods. It reveals high accuracy and reduces the shortcomings of those methods. Our experimental results confirm that the MW method improves the reconstruction accuracy and the stability of spectral-reflectance data. [ABSTRACT FROM AUTHOR]

Changes in maple wood’s pH and color (Acer pseudoplatanus) were evaluated before and after thermal treatment process with saturated water steam. Maple wood was thermally treated at temperatures: tI = 105 ± 2.5°C, tII = 125 ± 2.5 °C, and tIII = 135 ± 2.5 °C for τ ≤ 12 hours. Direct pH measurement of maple wood with a moisture content above the fiber saturation point (FSP) was performed using a pH-meter SI 600 with a Lance FET + H puncture probe. The polynomial dependence of pH and total color difference ∆E* on temperature t time τ was calculated by statistical processing of measured results. The correlation between the total color difference ∆E*of maple wood in the process of thermal color modification and the pH value is expressed y the equation: ∆E*= 4.5516∙(pH)² - 48.405∙(pH) + 134.35. This dependence is a suitable tool for assessing the achieved color change based on the change of wood pH in the technological process. [ABSTRACT FROM AUTHOR]

In order to achieve high-quality colour prints by using an electrophotography printing machine, it is necessary to prepare the printing substrate. Additional treatment may be needed to achieve the better substrate surface tension for optimally attaching the liquid electrophotography ink to the fine art paper. To ensure good adhesion of the ink to the printing substrate, a pre-treatment by application of surface tension regulating fluids (priming) may be used. In this paper, we will determine the possibility of realization of the CMY prints and the possibility of achieving an increased range of tone value in electrophotography digital printing. Based on the results, the new possible values of reproduced CMY tones will be determined so that a higher print quality can be achieved. The application of primers changes the optical properties of the paper printing substrate, which directly affects the colour reproduction. An additional 100 % increase of primer application will result in total colour changes of ΔEC (0,5g/m2&1g/m2) = 0,06, ΔEM (0,5g/m2&1g/m2) = 0,42, ΔEY (0,5g/m2&1g/m2) = 0,08. In this scenario, 1 g/m2 application of primer will produce the most intense full tones and therefore the highest quality prints for all three ElectroInk process colours. [ABSTRACT FROM AUTHOR]

In many applications in order to recognise the relationship between user and computer, the position at which the user looks should be detected. To this end, a salient object should be extracted that is attracted to the attention of the viewer. In this study, a new method is proposed to extract the object saliency map, which is based on learning automata and sparse algorithms. In the proposed method, after decomposition of an image to its superpixels, eight features (namely three features in red–green–blue colour space, coalition, central bias, rotation feature, brightness, and colour difference) are extracted. Then the extracted features are normalised to zero mean and unit variance. In this study, K‐means singular‐value decomposition is used to integrate the extracted features. The performance of the proposed method is compared with that of 20 other methods by applying four new databases, including MSRA‐100, ECSSD, MSRA‐10K, and Pascal‐S. The obtained results show that the proposed method has a better performance compared to the other methods with regard to the prediction of the salient object. [ABSTRACT FROM AUTHOR]

International Commission on Illumination (CIE) is an international organization working on the fundamental and scientific issues that can be applied to the evaluation of wide colour gamut (WCG) and high dynamic range (HDR) imaging. A model to estimate cone sensitivity with respect to age and field‐of‐view can be used to evaluate metamerism for WCG displays. CIE is developing new uniform colour space applicable for it in consideration of adaptations. [ABSTRACT FROM AUTHOR]

Maturity of a citrus fruit is generally expressed by a numerical value called citrus colour index (CCI). The success of methods employed in estimating the maturity depends on the cultivar and climatic conditions of growing regions. In this work, an image processing based method using CIELAB color model has been developed to estimate the CCI of Kinnow mandarin fruits. A polynomial transformation based camera characterization method was employed to reduce the number of transformations required for RGB to L ∗ a ∗ b ∗ colour space transformation, which resulted into a colour difference of 2.191 with CIELAB Δ E ∗ 2000 colour difference formula. In order to analyse the performance of this method, linear regression and partial least square (PLS) models were built on a dataset of 271 Kinnow fruit images wherein spectrophotometer was used for the validation of computed CCI values. The proposed method achieved a high adjusted R 2 value of 0.9660 using PLS regression, which ascertain the feasibility of image processing based system in estimating the maturity of Kinnow fruits. Additionally, a correlation analysis between colour coordinates and physicochemical properties was conducted to analyze the relation between the fruit's external peel colour and its internal characteristics. [ABSTRACT FROM AUTHOR]

The main aim of our current investigation is the colorimetric evaluation of protective treatments (consolidants) applied to traditional Islamic plasterworks, under natural ageing conditions. From analyses of the original pictorial plaster remains in the Courtyard of the Maidens of the Real Alcázar in Seville, Spain (a World Heritage Site) we prepared test specimens, using materials and techniques similar to the original ones. We analysed 56 test specimens painted with four pigments (yellow, green, blue, and red), using two different binders (animal glue and gum arabic), onto which five representative consolidants were applied: barium hydroxide, acrylic copolymer, polyvinyl butyral, ethyl silicate, and bacterial carbonatogenesis. The test specimens were subjected to natural ageing for one year (indoors and outdoors), enabling a colorimetric assessment to be made of the changes of the polychrome surfaces. The colorimetric heterogeneity of the 56 specimens after ageing registered an average value of 2.7 CIELAB units, assessed using the mean colour difference with respect to the mean. In the aged specimens, the addition of consolidants resulted in average colour differences (mainly lightness differences) of 10.7 and 6.7 CIELAB units, considering as a reference the specimens without consolidants aged indoors and outdoors, respectively. These colour differences were very similar for both binders but not for the four pigments, higher values being found for the blue and red pigments. Considering as reference the samples without consolidants aged outdoors, we found no statistically significant colour differences, either among the five consolidants (p = .094) nor the two binders (p = .674) used. In addition to the magnitude of colour differences, the choice of the most appropriate consolidants must also consider aspects related to performance and effectiveness. Overall, for the type of paints tested, the polyvinyl butyral consolidant appeared to perform the best, followed by the ethyl silicate. [ABSTRACT FROM AUTHOR]

Summary: The objective of this study was to determine the variation of the colour of longissimus thoracis muscle within and among fifteen European cattle breeds reared under comparable management conditions. A total of 436 unrelated purebred young bulls from fifteen European breeds (Aberdeen Angus, Highland, Jersey, South Devon, Danish Red, Holstein, Simmental, Asturiana de las Montañas (also known as Casina), Asturiana de los Valles, Avileña‐Negra Ibérica, Pirenaica, Marchigiana, Piemontese, Charolais and Limousin) were reared in five experimental research centres in the United Kingdom, Denmark, Spain, Italy and France. The pH of M. longissimus thoracis was measured at 24 h and after 10 days of ageing and colour at 48 h and 10 days. Two generalised linear models, Pearson correlations and a hierarchical cluster analyses were carried out. Lean meat colour differed significantly between breeds, and these fifteen European breeds could be grouped according to four classes of commercial interest: 'very bright and pale‐red', 'bright and pale', 'red' and 'dark and dull red'. These groups were partially related to body size and carcass traits, fatness and muscle development and structure, and were controlled by differences in gene expression within each breed. Classification of the 15 European breeds using the difference of colour (ΔE*) at 48 h. [ABSTRACT FROM AUTHOR]

In this paper were experimentally determined the colour differences between two pattern (standard and sample) with CIELAB formula in case of dying with natural dyes extracted from green nutshell. The dyes were made according to an experimental program at different concentration. The obtained dyes were used to estimate the colour differences that are usually a mixture of differences of brightness, saturation and nuance. In order to determine the intensity of the dyeing was measured at spectrophotometer Specord 200 the remission of the dyed samples. With their help were calculated the trichromatic values X, Y, Z and then the rectangular coordinates: L*- lightness coordinate, a* - the chromaticity coordinate for red-green colour area, b* - the chromaticity coordinate for yellow-blue colour area in CIELAB space. From these values derive the cylindrical coordinates: L*- lightness, C* -chroma, H* - nuance. The differences in colour ΔE between the samples and the standard sample are represented by distances between respective positions in CIELAB field and were calculated with some standardized relations. This colour differences were decomposed in: ΔL* - the difference in lightness ΔC* - the difference in chroma, ΔH* - the difference in nuance and calculated in CIELAB units. Were also made the diagrams: the position of the colours in CIELAB field, the chromatic diagram a*=f(b*), the lightness position and the colour differences between the samples and the standard sample.

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