The paper describes a comprehensive test to evaluate the performance of current colour‐difference models using available experimental datasets. In total, 28 individual datasets were accumulated to ...test 17 colour‐difference formulae, 13 of them based on Uniform Colour Spaces (UCSs) in terms of the Standardized Residual Sum of Squares (STRESS) measure. The 28 datasets were divided into three groups: Large Colour‐Difference data (LCD), Small Colour‐Difference data for surface colours (SCDs), and Small Colour Difference data for display colours (SCDd). For each colour model, four versions were tested: the original model, and that including kL‐, Gamma‐ and kL/Gamma, which are the lightness parametric factor, the colour‐difference exponent factor, and the combination of both, respectively, optimized to fit particular dataset(s). The statistical F‐test was applied to test the difference between each pair of models. Furthermore, parametric effects between the large/small colour‐difference magnitudes, and between surface/display colours were investigated. The results showed that CAM16‐UCS significantly outperformed the other models for all groups. It accurately predicted all types of data and should be proposed for colour‐difference evaluation across all industries.
Relative average scores achieved by each of the 17 colour‐difference formulas for: (A) original (V1) and (B) kL/Gamma (V4) models for each of three groups (SCDs, SCDd and LCD), assuming scores of 10 / 7.5 / 5 / 2.5 / 0 when a formula is significantly better / insignificantly better / identical / insignificantly worse / significantly worse than another one, respectively, from F‐test based on the STRESS index.11
•Lightness evaluation in specimens treated with TiO2 in the long term.•TiO2 effect on light radiation of coating mortars.•Aesthetic perception maintenance of facades treated with TiO2.•Solar ...absorption on surfaces treated with TiO2.•The color difference on surfaces treated by TiO2.
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 TiO2 answer to the lightness on the facade, different samples of TiO2 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 TiO2-P25p, TiO2-PC-S7s, and TiO2-E502s samples had the same effectiveness after exposure to artificial UV radiation, while the TiO2-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 TiO2 suspensions and specimens with TiO2 in powder. Beyond the absorptivity, the white painted specimens could be considered with low absorptivity. In contrast, the specimens treated with TiO2 suspension and those treated with TiO2 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.
•A facile method for preparing encoded upconversion silica nanoparticles.•A membrane biosensor is constructed for multiplex nucleic acids detection.•Colour differences are applied in upconversion ...luminescence for the first time.
Upconversion luminescent nanomaterials provide a powerful tool for multiplex nucleic acids detection simultaneously. However, the conventional encoding methods based on emission spectrum or intensity have limitations due to spectral overlap and cross-relaxation quenching among various activators. Herein, we present a facile method for the preparation of high-capacity upconversion luminescent coding nanoparticles by multiple regulating the synthesis kinetics of lanthanide ions doped CaF2 nanocrystals in mesoporous silica nanotemplets (named C@S). The secondary growth of nanocrystals with different lanthanide ions inside mesopores has a similar performance to that of core/multi-shell-structured upconversion nanoparticles prepared through complicated processes. The textural properties and chemical conformations are maintained after repeated recombination, which is beneficial for reproducible multiplex bioassays. A membrane biosensor is constructed using various probe-modified C@S and a flexible graphene oxide-coated film to detect and identify multiple molecular species in one sample. The colour differences of encoded C@S derived from CIE-L*a*b* colour coordinate system are applied to quantify the divergence of upconversion luminescence for the first time, which allows the upconversion nanoparticles with similar spectra and luminescence colours to be used in the same multiplex detection platform and avoids subjective judgement. This work opens new opportunities for upconversion luminescent materials in the field of automatic high-throughput detection.
Abstract Introduction Data on acceptability (AT) and perceptibility thresholds (PT) for colour differences vary in dental literature. There is consensus that the determination of Δ E * is appropriate ...to define AT and PT, however there is no consensus regarding the values that should be used. The aim of this clinical review was to provide a systematic approach to the topic of colour science of high clinical relevance to dental research. Materials and methods MEDLINE/PubMed, WoS and EBSCO databases were searched up to January 7, 2013; the outcome was restricted to English, and to clinical studies were spectrophotometers were used for measurement. Results Forty-eight studies were eligible and met the inclusion criteria. Of the 48 studies there appeared to be a trend in their source references: 44% referred to the same study for the PT (Δ E * = 1); and 35% referred to the same article for the AT (Δ E * = 3.7). Conclusions More than half the studies defined PT as Δ E * = 1, and one third of the studies referred to Δ E * = 3.7 as the threshold at which 50% of observers accepted the colour difference. Most clinical studies refer to the same few in vitro literature that have attempted to determine PT and AT from decades ago.
The colour of alcoholic beverages increases as they are aged in wood casks, due to the oxidation of the extracted phenols and tannic substances. In this paper, sixteen ageing experiments were carried ...out involving four different types of wood (American oak, French oak, Spanish oak and Chestnut), two toasting intensities (intense and medium toasting) and three initial wine distillates (holanda, wine spirit from a rectification column distillation and wine spirit from double distillation). Our experiments measured the CIEDE2000 colour difference as a control parameter for eight weeks. Four kinetic models were applied to better comprehend the evolution of the colour: Lagergren's first-order model, Peleg's pseudo-second-order model, an intra-particle diffusion model and a parabolic diffusion model. Differences on the non-linear correlation coefficients obtained by the Lagergren's and the Peleg's models show that the extractions are better fitted by the Peleg's model, leading to deduce that the colour obtained in the ageing process of the spirit is a second-order kinetic procedure. Differences between both diffusion models show that colours obtained from holandas are more strongly affected by side-reactions than colours obtained from wine spirits, probably due to their higher content in non-alcoholic compounds. Peleg's parameters show that toasting pre-treatments of wood also affect the kinetics of the colour obtained: intense toasted woods produce intense colours at the beginning of the ageing process, although medium toasted woods seem to produce more colour when equilibrium is reached.
•Colour evolution over time is explained by pseudo-second order kinetic models.•Colour is affected by reactions in high non-alcoholic compounds' content spirits.•Chestnut wood obtained more intense colours than oak woods, due to its porosity.•Higher toasting gives more colour at first times, but less colour in equilibrium.•Colour is obtained by three steps: washing step, diffusion step and chemical step.
Colour metrics for image edge detection Abasi, Saeedeh; A. Tehran, Mohammad; Fairchild, Mark D.
Color research and application,
August 2020, Volume:
45, Issue:
4
Journal Article
Peer reviewed
Image edge detection based on low‐level feature is usually performed on gray‐scale images. Some methods have been developed for edge detection on colour images based on low‐level feature, but they ...are not consistent with human colour perception. This research provides a new algorithm for edge detection based on the “HyAB” large‐colour‐difference formula. This algorithm uses Sobel operators for gradient‐magnitude calculations and Canny methods for localizing edge points. The performance of the new algorithm is qualitatively compared with Sobal and Canny methods using some challenging colour images. The results indicate that gradient magnitudes are best calculated using the HyAB colour‐difference formula, and that CIELAB and CIEDE2000 differences are not suitable for this purpose. Definition of gradient magnitudes according human perception is essential in applications such as quality control of fabric printing, calculation of disruptive colouration, and so on. The new algorithm is successful in accuracy and fine edge detection in comparison with the Sobel and Canny methods. The new method is quantitatively compared with state‐of‐the‐art methods using three datasets including BSDS500, MBDD, and BIPED. The correctness and accuracy of annotations of images in datasets have an important effect on results. The new method does not reach scores better than deep‐learning‐based methods, but it is simple and does not need training. It could probably have better results with improving noise‐suppression.
Compared to the conventional solar tanning, sunless tanning has become the most popular way to obtain tanned skin due to convenience and safety. Dihydroxyacetone (DHA), a three-carbon sugar, is the ...main active ingredient in commercial sunless tanning products and its tanning chemistry is similar to the well-known Maillard reaction. Whereas most studies concerning sunless tanning reaction, over the past 60 years, have focused on the amino groups of amino acids, little information is available on the impact of thiol groups of cysteine on the colour formation with DHA. Hence, this study systematically investigated the colour formation of cysteine and DHA using a simplified model system at different molar ratios, reaction times, pH, and temperatures. The colour change and characteristics were quantitatively evaluated using colour difference (ΔE*) and CIE L*a*b* values, respectively. In addition, the reactivity of amino and thiol groups on the same cysteine with DHA was further investigated. It was found, for the first time, that the thiol group of cysteine significantly inhibited the colour formation with DHA, while its amino group has a strong colour-formation ability in anhydrous condition. This work not only presents a systematic study on the colour formation of cysteine with DHA and the role of its amino and thiol groups, but also provides new knowledge for understanding and controlling the colour formation of DHA tanning on human skin.
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•Dihydroxyacetone (DHA)–cysteine (Cys) colour formation systematically investigated.•Colour change and colour properties of DHA–Cys evaluated using CIELAB colour space.•Colour-formation ability of Cys amino/thiol groups-DHA evaluated for the first time.•Cysteine thiol groups inhibit colour formation of Cysteine amino groups with DHA.
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•Asynchronous changes happen between anthocyanins content and color in storage.•Stored temperature at 4 °C were not friendly on color differences.•Predicted models could decrease ...visual differences in applications.
Anthocyanins of Lycium ruthenicum (LR) are valuable, whereas stabilities, especially colour stabilities, constrain development. This study investigates stored temperature effects on the stability of powdered anthocyanin extracts of LR in anaerobic conditions and colour changes in simulated applications. We found that temperature had limited effects on anthocyanin contents but negative effects on colour. Colour differences (ΔE) were amplified in simulated applications, 4 °C had the most changes in ΔE in simulated applications, 37 °C caused shrinkage of the colour range towards the yellow area, and changes in ΔE at pH 7 and 9 were summarized by models. In conclusion, during anaerobic storage of powdered anthocyanins, asynchronous changes occur between anthocyanin contents and colour. High storage temperature attenuates colour intensity, but low storage temperature causes more ΔE in applications. Established models are beneficial for decreasing the visual differences in products, deepening the understanding, and offering a new perspective on colour analysis.
Steel structures exposed to the outdoors experienced several types of corrosion, which may reduce their thickness. Since atmospheric corrosion can induce economic losses, it is important to consider ...the atmospheric corrosion behavior of a variety of metals and alloys. This work performed outdoor exposure tests for 10 years at 14 areas in Korea and calculated the atmospheric corrosion rate of weathering steel. This paper discussed the atmospheric corrosion behavior of weathering steel based on various corrosion factors. The average corrosion rates in coastal, industrial, urban, and rural areas were found to range from (2.83 to 4.23) μm/y, (2.99 to 4.23) μm/y, (1.72 to 3.14) μm/y, and (1.57 to 2.85) μm/y respectively. It should be noted that the maximum corrosion rate was about 6.0 times greater than the average corrosion rate. Regardless of the exposure sites, the color differences were increased, but the glossiness was reduced and there was no relationship between the corrosion rate and environmental factors and the glossiness.
