Minimum ΔE Research Articles

Analyzing Color Difference of Digital Cameras Under Different Color Temperatures

Purpose : Dental clinics had a variety of lighting conditions, which could affect digital photography. Digital Single-Lens Reflex Camera (DSLR) was usually used to take intraoral photos. Recently, there has been a growing trend to use smart-phones with the advancement of technology. The aim of this study was to analyze the differences of photographs taken with digital and smartphone cameras under different color temperature conditions.Materials and Methods : Three types of camera equipment were used: a DSLR (EOS 800D; Canon, Tokyo, Japan) with a macro lens (EF 100mm f/2.8 Macro USM, Tokyo, Japan) and diffuser (Lumilab, Gimpo, Korea) and two types of smart-phones; Galaxy (Samsung, Suwon, Korea) and iPhone (Apple, California, USA) with Smile line MDP (Smile line SA, St-lmier, Switzerland). All photographs were taken 30 times for every 500°K color temperature from 3500°K to 6000°K. Color information was extracted from the central part of the tooth using image editing software (Adobe Photoshop CS4, Adobe, California, USA). ΔE value was calculated by this formula based on CIE L*a*b* color systems. All statistical analyses were performed using SPSS (version 23, SPSS, Chicago, USA), with a significance level of 0.05.Results : In this study, DSLR showed the highest ΔE value followed by iPhone and Galaxy. DSLR showed minimum ΔE value in 4O00°K, iPhone and Galaxy showed in 4500°K. The lowest L* value was DSLR, followed by iPhone and Galaxy. The highest a* value was DSLR, followed by iPhone and Galaxy, except for 4000°K. The lowest b* value was DSLR, followed by Galaxy and iPhone. So DSLR was the darkest, reddest, and bluest of the three equipment.Conclusion : Although there was a significant difference from the actual shade, Galaxy showed the most similar color. Because each device showed different results, it was essential to consider the characteristics of each imaging device.

Chromaticity of Gromwell, Cape jasmine Dyeing, and Effects of Zinc Oxide/Polyphenol Treatment with Copper Mordanting for UV Protection

To protect skin from harmful ultraviolet (UV) radiation, there has been a resurgence in the use of natural dyes with metal mordants to reduce contamination by advanced chemicals. This study achieved natural dyeing in violet and yellow colors from Gromwell red roots and Cape jasmine seeds for UV-protective materials. The dyed fabrics were subjected to zinc oxide (ZnO) and polyphenol treatments, as well as copper post-mordanting. The SEM, TEM, and XRD tests showed that the ZnO nanoparticles, with hexagonal crystal structures, stuck to the fiber surfaces, and twisted strands resulted in the K/S reduction. First, this study found that the untreated cotton in violet, despite the highest K/S, faded the most intensely when exposed to UV. The color variation of untreated polyester was narrow, with little change in L, a*, and K/S. The color change of yellow-dyed samples treated with ZnO/polyphenol was not considerable in yellowness (b*: 28.838), while the violet fabrics displayed a significant decrease in K/S and an increase in b*. The combination of ZnO and polyphenol treatment improved UV absorption at 350 to 250 nm. Among the Cu-mordanted fabrics after ZnO/phenols treatment, the violet cotton turned reddish from blueish (negative to positive b*), with a hue change of 316° to 59° and the highest ΔE (25.90 ± 4.34) after UV exposure. In this study, the combination of ZnO/polyphenol with Cu-mordants allowed the Cape jasmine-dyed polyester to achieve a minimum ΔE as well as to keep its chroma and hue after UV exposure.

Effects of curing time and intensity and polishing technique on color stability of bleach-shade composite resins

Background: Despite the improvements in optical properties of composite resins, their color stability is still a matter of concern. This study aimed to assess the curing time and intensity and polishing technique on color stability of bleach-shade composite resins. Materials and Methods: In this in vitro, experimental study, 128 discs (1 mm × 8 mm) were fabricated from two composite resins. The specimens fabricated from each composite were assigned to 8 subgroups (n = 8) based on the curing time and intensity and polishing with polishing points or discs. After polishing, the color parameters of specimens were measured by EasyShade spectrophotometer according to the CIEL* a*b* color system. The specimens were then immersed in tea solution, and their color parameters were measured again. Color change (ΔE) was calculated and analyzed at 0.05 level of significance. SPSS 25 was used for data analysis. Univariate four-way ANOVA was applied to assess the effects of composite type, curing time, curing intensity, and technique of polishing on ΔE of composite resins. Since the interaction effects were significant, subgroup analysis was performed by t-test. The level of significance for this test was set at 0.05. Results: The effects of curing intensity and polishing technique were significant on ΔE (P < 0.05). Filtek Z350 XBW composite specimens polished by polishing points experienced lower color change than those polished with discs. The minimum ΔE of Gradia XBW composite was recorded in specimens that underwent high-intensity curing for 20 s and were polished with polishing points while the maximum ΔE was recorded in specimens that underwent high-intensity curing for 20 s and were polished with discs. Conclusion: In all groups except on (Filtek, polishing with Disk, curing time = 20 s), high-intensity curing and polishing with polishing points were more effective and caused lower color change compared with low-intensity curing and polishing with discs.

The effect of adding silver nanoparticles on the color stability of feldspathic porcelains

Background: This study aims to investigate the color stability of feldspathic porcelains with different concentrations of silver nanoparticles (AgNPs). Materials and Methods: In this experimental study, feldspathic porcelain disks with AgNPs of 0 parts per million (ppm), 250 ppm, and 500 ppm were used (sample size = 180). These ceramic discs were subjected to thermocycling in tea, orange juice, and artificial saliva. The optical parameters of disks were measured before and after being immersed in the solutions. Then, the color change (ΔE 00) of the samples was measured by using the CIEDE 2000 formula. The data were analyzed by one-way analysis of variance (ANOVA) and Tukey's post hoc test. The level of significance was determined to be 0.05. Results: The results of the ANOVA test show that there was a significant difference in ΔE 00 (P ≤ 0.05). The maximum ΔE 00 was visible in the samples with AgNPs 0 ppm that were exposed to orange juice, and the minimum ΔE 00 was related to the disks with AgNPs 500 ppm in artificial saliva. Conclusion: Based on the results of this study, adding AgNPs to feldspathic porcelain increases the color stability of the ceramic discs.

Evaluation of the value of re-wetting prior to resin infiltration of post-orthodontic caries lesions

Assessment of the influence of colour changes during the re-wetting process as a possible predictor for the final result after resin infiltration to mask post-orthodontic white spot lesions. Resin infiltration (ICON; DMG, Hamburg, Germany) was performed according to the manufacturer's recommendation with the exception of repeated, at maximum three etching procedures based on the subjective decision of the dentist during a so called re-wetting process using ethanol. The masking effect by ethanol as well as after resin infiltration was evaluated by digital images taken before, for nine seconds during re-wetting and one week after treatment using CIE L*a*b* colour space. Twenty-nine patients (16 female) with a total of 221 lesions (ICDAS 2) were included (mean age 16 years). Mean time after debonding the orthodontic appliances was ten weeks. Colour changes during re-wetting, evaluated in the first ten patients (71 lesions) showed a significant correlation between the minimum ΔE observed during re-wetting and the final ΔE after resin infiltration (r = 0.65, p < 0.001; Spearman correlation). The main drop in ΔE becomes visible after three seconds when performing the re-wetting process. Regarding the 221 lesions, resin infiltration significantly reduced the colour difference between sound and lesion areas from a baseline ΔE (25th/75th percentiles) of 10.9 (8.2/13.2) to a ΔE of 4 (2.1/5.8) after one week (p < 0.001). The number of etching procedures correlated significantly with baseline ΔE (p < 0.05). The minimum ΔE observed during the re-wetting process seems to be a useful predictor for the final result of resin infiltration of post-orthodontic caries lesions. More prominent lesions with higher ΔE at baseline seem to require more erosion of the surface layer. In general, a significant and considerable clinical reduction of ΔE could be observed. We corroborate that resin infiltration technique is a very useful method to mask caries lesions having developed during treatment with fixed orthodontic appliances. Colour changes while re-wetting the lesions with ethanol seem to be a valuable indicator for the number of required etching procedures.

Segment‐interpolation and gamut mapping application of segment maxima gamut boundary descriptors

AbstractThe segment maxima gamut boundary descriptor is applied prevalently in cross‐media color reproduction. But irregular color distribution may generate many vacant segments, especially when calculating the gamut boundary. It will reduce the accuracy of gamut boundary description seriously. This article proposes an interpolation algorithm for vacant segments based on neighboring weighted average. To address the problems caused by the coincidence between the line connecting two adjacent gamut boundary descriptor points and the constant hue plane, the reasonable solutions are given for calculating line gamut boundaries. Based on segment maxima gamut boundary descriptor, the article designs a typical gamut‐clipping operator “Hue‐preservation Minimum ΔE (HpMinDE)” and a gamut‐compressing operator. The calculation of intersections between line gamut boundaries and gamut mapping lines is also analyzed. It can help to determine quickly to which segment a gamut mapping line belongs, thus improving the gamut mapping efficiency. In the assessment, the accuracy of “HpMinDE” operator is evaluated by means of the color difference calculation. Then, the psychophysical experiments are employed to evaluate the preference and accuracy of the gamut‐compressing operator. Finally, the computational efficiency of gamut boundary descriptor and gamut mapping operators are tested and verified.

Polymer complexes. LXXI. Spectroscopic studies, thermal properties, DNA binding and antimicrobial activity of polymer complexes

Polymer complexes of Co(II), Ni(II), Mn(II), Cr(III) and Cd(II) were prepared by the reaction of 3‐allyl‐5‐[(4‐nitrophenylazo)]‐2‐thioxothiazolidine‐4‐one (HL) with metal ions. The structure of polymer complexes was characterized by elemental analysis, IR, UV–Vis spectra, X‐ray diffraction analysis, magnetic susceptibility, conductivity measurements and thermal analysis. Reaction of HL with Co(II), Ni(II), Mn(II), Cr(III) and Cd(II) ions (acetate or chloride) give polymer complexes (1–5) with general stoichiometric [M(L)(O2CCH3)(H2O)2]n (where L = anionic of HL and M = Co(II) (1) or Ni(II) (2)), [Mn(HL)2(OCOCH3)2]n (3), [Cr(L)2(Cl)(H2O)]n (4) and [Cd(HL)(O2CCH3)2]n (5). The value of HOMO–LUMO energy gap (ΔE) for forms (A‐C) of monomer (HL) is 2.529, 2.296 and 2.235 eV, respectively. According to ΔE value, compound has minimum ΔE is the more stable, so keto hydrazone form (C) is more stable than the other forms (azo keto form (A), azo enol form (B)). The interaction between HL, polymer complexes of Co(II), Ni(II), Mn(II), Cr(III) and Cd(II) with Calf thymus DNA showed hypochromism effect. The HL and its polymer complexes were tested against some bacterial and fungal species. The results showed that the Cr(III) polymer complex (4) has more antibacterial activity than HL and polymer complexes (1–3 and 5) against Bacillus subtilis, Staphylococcus aureus and Salmonella typhimurium.

Using response surface methodology to investigate bone china characteristics: (II) physical characteristics

This study deals with investigating the effect of feed composition on bone china optical characteristics using response surface methodology (RSM) by MATLAB software. In this regard, based on batch calculation diagram, 13 feed compositions were chosen and investigated according to RSM methodology. The optical characteristics that were studied are L*, a*, and b* which are representative of brightness, blue, and red colors. Results showed that brightness L* can be modeled by feed composition but a* and b* are functions of impurities and firing environment and cannot be modeled just by considering feed composition. There is also another parameter known as ΔE that represents the difference between the color of sample and a reference color. Since the lower amount of ΔE is the best, a minimization by Levenberg-Markared method was done and the minimum ΔE figured out to be at 58% bone ash, 21% feldspar, and 21% kaolin.

Cross‐media colour gamut mapping model for the preservation of visual differentials in layer‐tinted maps

Aiming at solving the colour union, variation and loss problems during cross-media reproduction in the layer-tinted map, this study proposes a colour gamut mapping model for the preservation of visual differentials in layer-tinted maps. First, many layer-tinted maps are collected for analysis and the colouring rules are concluded. Then, the dominant and non-dominant colours are extracted based on the colour gamut characteristics of the maps. For the mapping of dominant colours, the corresponding Munsell's three colour dimensions are calculated by establishing the transformational relation between CIELAB colour space and Munsell's colour system and then the colour gamut mapping of dominant colours is achieved in the Munsell's colour order system. On the other hand, the mapping of non-dominant colours is achieved by hue-angle preserving minimum ΔE clipping. The experimental results indicate that compared with the four colour gamut mapping methods recommended by the International Color Consortium, the proposed algorithm in this study can more easily distinguish the hierarchical information in the maps and perfectly remain the visual differentials among the layered colours.

High hydrostatic pressure effect on chemical composition, color, phenolic acids and antioxidant capacity of Cape gooseberry pulp (Physalis peruviana L.)

The aim of this study was to evaluate the effects of high hydrostatic pressure (HHP) at 300, 400 and 500 MPa/1, 3 and 5 min on nutritional and antioxidant properties of Cape gooseberry pulp after immediate application and after 60 days of storage. Proximal analysis, color, phenolic acids content and antioxidant capacity were determined. When analyzing the immediate effect of different treatments, a clear influence of HHP was observed in all the components of the proximal analysis. Regarding color, none of the three chromatic parameters showed significant differences with control leading to a minimum ΔE at 300 MPa/3 min. Changes in bound and free phenolic acids were evidenced after treatments. The maximum levels of TPC as well as antioxidant capacity were observed at 500 MPa/5 min. By the end of storage, all treated samples discolored leading to ΔE = 14.9 at 500 MPa/5 min. The profile of free and bound phenolic acids presented differences compared to Day 0. The antioxidant capacity by means of ORAC increased for treatments above 300 MPa/5 min indicating the effectiveness of these treatments for the production of functional products based on gooseberry pulp. For treatments above 400 MPa/3 min, molds and yeasts were not detected.

Screening of JAK2 V617F and MPL W515 K/L negative essential thrombocythaemia patients for mutations in SESN2, DNAJC17, ST13, TOP1MT, and NTRK1

Screening of <i><scp>JAK</scp>2</i> V617F and <i>MPL</i> W515 K/L negative essential thrombocythaemia patients for mutations in <i><scp>SESN</scp>2, <scp>DNAJC</scp>17, <scp>ST</scp>13, <scp>TOP</scp>1<scp>MT</scp>,</i> and <i><scp>NTRK</scp>1</i>

Optimization of Combined Heat Pump and Microwave Drying of Yacon (S mallanthus sonchifolius ) Using Response Surface Methodology

Response surface methodology was employed to investigate the effects of drying temperature (15.0–45.0C), air velocity (1.00–2.00 m/s), moisture content at conversion point (40.0–60.0%) and microwave (MW) power (1.0–3.0 W/g) on the average drying rate (DR), specific moisture evaporation rate (SMER), total color difference (ΔE), rehydration ratio (RR) and shrinkage ratio (SR) of yacon dried by combined heat pump (HP) and MW methods. A central composite rotatable design was used to develop models for responses. The coefficients of determination R2 of DR, SMER and ΔE were higher than 0.7. However, R2 of RR and SR were 0.540 and 0.343, respectively. Based on response surface and desirability functions, the optimum conditions for combined HP and MW drying of yacon were drying temperature of 42.7C, air velocity of 1.69 m/s, moisture content at conversion point of 50% and MW power of 2.0 W/g. At this optimum point, DR, SMER and ΔE were 0.262 kgH2O/kg(d.b.)·h, 0.222 kg/kW·h and 23.59, respectively. Practical Applications Yacon are rich in essential amino acids, minerals and fructooligosaccharides (FOS). However, FOS hydrolyzation, browning and decay are the common phenomena during postharvest storage and transportation. Hybrid drying techniques are being developed to minimize weakness and maximize merits of different drying techniques to produce better quality of foodstuffs, reduce drying time, decrease energy consumption and increase drying efficiency. Therefore, response surface methodology was employed to investigate the effects of drying temperature, air velocity, moisture content at conversion point and MW power on the average DR, SMER, ΔE, RR and SR of yacon dried by combined HP and MW methods, and the optimum process conditions were determined to obtain the criteria of maximum DR and SMER, and minimum ΔE. This research will provide valuable information for industrialization of yacon dried by combined HP and MW methods.

Applicability of CIELAB/CIEDE2000 formula in visual color assessments of metal ceramic restorations

To investigate the applicability of color-difference formula (CIELAB or CIEDE2000) in visual color assessments of metal-ceramic specimens in small color-difference ranges. Metal-ceramic specimens using mixture of gradient ratio porcelain powders were fabricated to create a color pool. Color differences of specimen pairs were calculated using the CIELAB (ΔE(ab)(∗)) and CIEDE2000 (ΔE(00)). A questionnaire, composed of 1 target and 3 enactment specimens, was designed. For formula-determination, the enactment specimen with the minimum ΔE to the target specimen was registered as FS. For visual-assessment, twenty participants were asked to finish the questionnaire by choosing the most color-matched enactment specimen to the target. The percentage of the FS been selected (P(FS)) was calculated, which was used to represent the consistence of formula-determination and visual-assessment. Binomial Tests were used to compare the differences between P(FS) values and 33% (the randomized probability of the FS been selected was one out of three, approximate 33%). Regression analysis was used to determine the correlation between ΔE(ab)(∗) and ΔE(00) values. A linear regression equation was drawn as ΔE(00)=-0.049+0.619×ΔE(ab)(∗). There were no significant differences between P(FS) values and 33% within the range of ΔE(ab)(∗)<2.0, whereas P(FS) values were significantly higher than 33% when ΔE(ab)(∗)>2.0 (P<0.001). There was a tendency of selecting the enactment specimens with lower L* values and higher b* or C' values, within the range of 1.0<ΔE(ab)(∗)<2.0. CIE color-difference formulas were not applicable for visual color assessments of metal-ceramic specimens within the color-difference range of ΔE(ab)(∗)<2.0.

Evaluation of self shade matching ability of dental students using visual and instrumental means

The purpose of this study was to evaluate the ability of dental students to match the shade of their own teeth. Fifty female dental students in the College of Dentistry at King Saud University, who had not received any formal dental training in color science or shade matching procedures, were screened for color deficiencies and selected to participate in the study. Each subject and three clinicians selected independently the closest match for the subjects' own right or left sound maxillary central incisors under controlled viewing conditions, using VITA classical shade guide (VITA Zahnfabrik GmbH, Bad Säckingen, Germany). Each examined central incisor and the 16 samples of VITA classical shade guide were measured with the VITA Easy Shade (VES) spectrophotometer to determine the CIELAB color parameters. The color differences (ΔE) between each examined tooth and the 16 samples of the shade guide were calculated. The minimum ΔE values were compared to ΔE values of the shade obtained by VES, subjects and clinicians. The results showed a significant difference in the accuracy of shade selection between the instrumental and visual means. ΔE value of shade selected by clinicians was significantly lower than those selected by the subjects. It was concluded that, spectrophotometric shade analysis was more accurate compared to human shade assessment. A reliable self-perception of the subjects' own tooth color, may aid in the shade matching procedures. It might lead to increased patients' satisfaction at the finalization of the restorative procedures.

Colorimetric comparison of light-filtering intraocular lenses and human crystalline lenses at various ages

To perform colorimetric characterization of 2 blue light-filtering intraocular lens (IOL) models and an IOL that filters ultraviolet-violet (UV-v) light and compare the charactizations with those of a standard UV light-filtering IOL and the human crystalline lens at various ages. Department of Clinical Physiopathology, University of Florence, and National Institute of Applied Optics, CNR, Florence, Italy. Experimental study. Three IOLs of each model with different dioptric powers (16.0, 21.0, and 26.0 diopters) were analyzed. The colorimetric coordinates of the IOLs were calculated by measuring their transmission spectra using a microspectroscopy technique. Subsequently, a parameter (ΔE) that was proportional to the perceived color differences was defined. The results of the IOLs and of the human crystalline lens at different ages (4, 22, 41, 53, and 72 years; values taken from the literature) were compared. The colorimetric analysis was performed using Commission Internationale de l'Éclairage standards. The maximum ΔE value was with the standard UV light-filtering IOL at any crystalline lens age and was greatest with a 72-year-old human lens. The minimum ΔE value was obtained for both blue light-filtering IOLs with middle-aged human lenses. None of the analyzed IOLs had the same colorimetric performance of the human crystalline lens. The 2 blue light-filtering IOLs best reproduced yellowing of the human lens at 40 to 50 years of age. No author has a financial or proprietary interest in any material or method mentioned.

The optimization of the extrusion process when using maize flour with a modified amino acid profile for making tortillas

SummaryMaize with a modified amino acid profile, i.e. greater amounts of lysine and tryptophan than normal, is known as ‘quality protein maize’ (QPM). The objective of this work was to find the best combination of extrusion process variables to produce QPM flour for making tortillas. QPM grits were mixed with lime and water and had a moisture content of 28%. The single screw extruder operation conditions were selected from factorial combination of three process variables: extrusion temperature (ET, 70–100 °C), lime concentration (LC, 0.1–0.3% of the maize weight) and screw velocity (SV, 80–250 rpm). Response surface methodology was used as an optimization technique. In vitro protein digestibility (PD); total colour difference (ΔE) of the flours, and tortilla puffing (TP) were chosen as response variables. A graphical method was used to obtain maximum PD, TP and minimum ΔE. The optimum combination of process variables was: ET = 85 °C/LC = 0.21%(w/w)/SV = 240 rpm. Tortillas from QPM flour had similar chemical composition, physicochemical and sensory properties to tortillas from commercial nixtamalized maize flour; however, the former had the highest (P ≤ 0.05) available lysine content and were therefore better nutritionally.

Optimisation of extrusion process to transform hardened chickpeas (Cicer arietinum L) into a useful product

AbstractThe objective of this work was to determine the optimum conditions for the production of extruded flour from hardened chickpeas (Cicer arietinum L). Hardened chickpeas were produced using accelerated storage at 33–35 °C and 76% relative humidity for 160 days. Hardened chickpeas were broken, dehulled and softened with a salt solution (2.5 g l−1 NaCl + 7.5 g l−1 NaHCO3 in distilled water) prior to extrusion. The single‐screw extruder operation conditions were selected from factorial combinations of process variables: extrusion temperature (ET, 130–160 °C), feed moisture content (FMC, 200–300 g H2O kg−1, wet basis) and screw velocity (SV, 150–200 rpm). Response surface methodology was applied as optimisation technique over four response variables: in vitro protein digestibility (PD), total colour difference (ΔE), water absorption index (WAI) and water solubility index (WSI). Predictive models for response variables were developed as a function of process variables. The conventional graphical method was applied to obtain maximum PD and WAI and minimum ΔE and WSI. Contour plots of each of the response variables were utilised, applying superposition surface methodology to obtain three contour plots for observation and selection of the best (optimum) combination of ET (150.5 °C), FMC (265 g H2O kg−1) and SV (190.5 rpm) for the production of extruded flour from hardened chickpeas with a single‐screw extruder. Extrusion significantly improved the in vitro protein digestibility (21.7%) and protein efficiency ratio (36.9%) of hardened chickpeas.© 2002 Society of Chemical Industry

Kinetic Study on Color Changes in Milk Due to Heat

ABSTRACTAnalysis of changes in terms of color difference (ΔE) and yellowness index (YI) permits evaluation of severity of heat treatment of milk. Both ΔE and YI increased at constant temperature following zero‐order kinetics, at temperatures between 90 and 130°C for 1 to 60 min. Activation energy, according to the Arrhenius equation, was 101.8 and 117.5 KJ/mol for ΔE and YI, respectively. Comparison of instrumental and sensory data showed a minimum ΔE of 3.8 would be attained before visual perception of milk browning. Color values, such as ΔE or YI, are proposed as the simplest and most reproducible indices of commercial milk quality.