Color Difference Measurement Research Articles

Optical, structure and thermal investigation of the effect of gamma radiation in CPVC/Ag and CPVC/Pd nanocomposites membrane

ABSTRACTThe updated Nanostructure materials and nano-technological tools are predicted to enable the synthesis polymer–inorganic composites to manufacture higher qualified membranes possess attractive physical and chemical properties with high performed sensitivity and selectivity. In this study carboxylated poly (vinyl chloride) (CPVC), CPVC/silver and CPVC/palladium nanocomposites membranes were prepared. Samples from the CPVC/Ag and CPVC/Pd nanocomposites films were irradiated with gamma doses in the range 25–150 kGy. The structural modifications in the gamma-irradiated nanocomposite samples have been studied as a function of dose using different characterization techniques such as X-ray diffraction XRD, UV spectroscopy, color difference studies, Thermogravimetric analysis TGA and scanning electron microscope SEM. The results indicate that the gamma irradiation in the dose range 50–150 kGy led to a more compact structure of both CPVC/Ag and CPVC/Pd nanocomposite films, which resulted in an improvement in its thermal stability with an increase in the activation energy of thermal decomposition and amorphous phase. It is worth mentioned that the nano-palladium is more effective than nano-silver composite membranes in stabilizing the CPVC. In addition, the results of color difference measurements indicated that both the CPVC/Ag and CPVC/Pd nanocomposite films acquire color under gamma irradiation up to 150 kGy, but the response of CPVC/Ag to color changes is higher. For this reason, the CPVC/Ag nanocomposite film was chosen to be a subject for the further study to investigate the effect of gamma irradiation on its optical and microscopic properties. it is found that the gamma irradiation reduces the optical energy gap that could be attributed to the increase in structural disorder of the irradiated CPVC/Ag nanocomposite due to crosslinking.

Evaluation of color differences in natural scene color images

Since there is a wide range of applications requiring image color difference (CD) assessment (e.g. color quantization, color mapping), a number of CD measures for images have been proposed. However, the performance evaluation of such measures often suffers from the following major flaws: (1) test images contain primarily spatial- (e.g. blur) rather than color-specific distortions (e.g. quantization noise), (2) there are too few test images (lack of variability in color content), and (3) test images are not publicly available (difficult to reproduce and compare). Accordingly, the performance of CD measures reported in the state-of-the-art is ambiguous and therefore inconclusive to be used for any specific color-related application.In this work, we review a total of twenty four state-of-the-art CD measures. Then, based on the findings of our review, we propose a novel method to compute CDs in natural scene color images. We have tested our measure as well as the state-of-the-art measures on three color related distortions from a publicly available database (mean shift, change in color saturation and quantization noise). Our experimental results show that the correlation between the subjective scores and the proposed measure exceeds 85% which is better than the other twenty four CD measures tested in this work (for illustration the best performing state-of-the-art CD measures achieve correlations with humans lower than 80%).

Spectrophotometric Evaluation of Urethane Acrylate Based Pigment Colour Stability

The aim of the paper is to analyse the influence of violet and green pigment concentration on acrylate coating colour stability with increased temperature and in UV light. A set of coating formulations were generated with different pigment mass concentrations (0, 1% to 5%) and coating colour change were evaluated at room temperature, at 50°C and in direct sunlight over a 28 day period. After application and UV cure, the samples were examined using spectrometric methods. Spectrometric colour difference measurements were performed using colour system CIEL*a*b* to evaluate their stability over time. It was found that increasing pigment concentration improves the colour stability.

Suitability of a Mobile Phone Colorimeter Application for Use as an Objective Aid when Matching Skin Color during the Fabrication of a Maxillofacial Prosthesis.

Color matching a facial prosthesis to human skin is very challenging. Colorimeters aid this process by adding objectivity to what is an otherwise subjective procedure. Mobile phone colorimeter applications offer a less expensive and widely available alternative to dedicated colorimeter devices for color measurement. There is a lack of evidence in the literature regarding the suitability of mobile phone colorimeter applications for the development of silicone shades for facial prosthetics. The purpose of this study is to determine the suitability of a mobile phone colorimeter application for matching natural skin colors during the fabrication of maxillofacial prostheses. Ten pigmented maxillofacial silicone elastomer swatches were fabricated to mimic a range of human skin tones. Color measurements of these swatches were recorded using a test instrument-the mobile phone colorimeter application (RGB Colorimeter) and a reference instrument-the commercially available skin color measurement device e-skin spectrocolorimeter. Comparisons in trueness and precision of the color measurements were made using previously described methods. Data analysis was performed on the recorded results for each of the parameters at three distances (25, 30, and 35 mm) of the test instrument from the target against both a black and a white background. The trueness of the mobile phone colorimeter application relative to the colorimeter device varied depending on the distance from the target and the background color. The relative trueness of the color difference measurements fell just within the documented upper threshold of acceptable limits of color difference (∆E 3.0 - 4.4). The calculated precision of the CIE L*a*b* and ∆E measurements of the mobile phone colorimeter application was good, with the latter being well within the documented acceptable limits. A mobile phone colorimeter application would be a suitable aid in objectifying the process of color matching a silicone maxillofacial prosthesis. Further investigation into image calibration to improve trueness and the control of variables such as background noise, uniformity of illumination, and measuring distance is required.

Human Factor Consideration on Color Consistency in Flight Deck

The essential factors for information legibility and the evaluation approach for aviation chromaticity difference and luminance difference measurements are analyzed in this paper. Based on the color difference measurement given by display-related aviation regulation, one algorithm which is applicable for cross-area color consistence is proposed. This algorithm not only provides one evaluation method for different color application area but also effectively reduces human perceptual color difference.

Gamma-induced changes in some of the structural and optical properties of Makrofol polycarbonate/silver nanocomposites films

ABSTRACTNano-sized silver (Ag) was prepared and mixed with Makrofol polycarbonate (PC) (5 wt%) to produce nanocomposites films. Samples from the PC/Ag nanocomposite films have been exposed to gamma radiation in the dose range of 20–300 kGy. The consequential effect of gamma radiation has been studied using X-ray diffraction, fourier transform infrared spectroscopy and UV spectroscopies and color difference measurements. The results indicate that the gamma irradiation up to ∼150 kGy increases the intermolecular interaction of PC chains and Ag that could be attributed to crosslinking that destroys the ordering structure, giving the polymer more resilience. This was accompanied with a reduction of the optical energy gap and an increase in refractive index. In addition, the color intensity, which is the color difference between the irradiated samples and the non-irradiated one, increases with increasing the gamma dose at the range of 20–150 kGy, accompanied with an increase in the blue and green color components.

Studies on the Degradation of Poly(Ethylene-co-vinylacetate)/Polylactides/TiO<SUB>2</SUB> Nanocomposites Under Accelerated Weathering

This study deals with the degradation of poly(ethylene-co-vinylacetate) (EVA)/polylactide (PLA) blend and EVA/PLA/TiO nanocomposites under accelerated weathering stimulation. The aging process was carried out by alternating cycles of UV light and moisture at controlled and elevated temperatures. The degradation of these materials was characterized by Fourier transform infrared spectroscopy (FTIR), color difference measurement, tensile test, thermogravimetric analysis (TGA) and field emission scanning electron microscopy (FESEM) observation. The FTIR and color difference results showed that the chemical structure of the blend and nanocomposites underwent changes during the weathering process. After the testing, the tensile properties and thermal stability of both the blend and nanocomposites showed a considerable reduction. The appearance of many micro-holes and micro-pores on the surface of the collected samples was observed. The presence of TiO nanoparticles promoted the degradation of EVA/PLA blend.

Effect of sample layer numbers and fabric constructional parameters on colour strength, colour difference and colour matching properties of polyester woven fabrics

This paper focused on the effect of different fabric layer numbers on colour strength (K/S), colour difference () and colour matching properties of polyester fabrics woven with different constructional parameters. Colour strength and colour difference measurements were conducted on the dyed fabric samples at six (1, 2, 3, 4, 8 and 16) different fabric layers. Polyester fabrics having different constructional parameters were used and the fabrics differed from each other by their weft yarn filament fineness (fibre count), weft yarn densities and weave patterns in the experimental subgroups. Warp yarn type and count, warp density and warp yarn twist were the same in the subgroups. Colour strength, colour difference and colour matching properties were discussed depending on constructional parameters and fabric layer numbers. Colour difference values of the fabrics decreased as layer numbers increased. However, they increased as fibres in fabric structure became finer, as weft densities decreased and as weave patterns differed from plain to sateen. Colour matching between different constructed polyester fabrics became easier when plain patterns and high weft densities were used, i.e. when compactness increased. Usage of finer filament yarns caused fabric compactness to increase but colour matching became more difficult under certain circumstances. Colour matching became easier with increasing compactness but usage of different filament fineness affected the ease of matching depending on fabric constructional properties.

Colour-Difference Measurement Method for Evaluation of Quality of Electrolessly Deposited Copper on Polymer after Laser-Induced Selective Activation.

In this work a novel colour-difference measurement method for the quality evaluation of copper deposited on a polymer is proposed. Laser-induced selective activation (LISA) was performed onto the surface of the polycarbonate/acrylonitrile butadiene styrene (PC/ABS) polymer by using nanosecond laser irradiation. The laser activated PC/ABS polymer was copper plated by using the electroless copper plating (ECP) procedure. The sheet resistance measured by using a four-point probe technique was found to decrease by the power law with the colour-difference of the sample images after LISA and ECP procedures. The percolation theory of the electrical conductivity of the insulator conductor mixture has been adopted in order to explain the experimental results. The new proposed method was used to determine an optimal set of the laser processing parameters for best plating conditions.

Quality assessment and modeling of microwave-convective drying of lemon slices

Juice production is the most important process used for citrus fruits. However, drying process applied in the production of powders, flakes, and slices is also of great importance. Drying behavior of lemon slices was investigated using convective (50, 55 and 60 °C inlet air temperatures), microwave (specific power of 0.97 W g−1), and combined microwave-convective (specific powers of 0.97 and 2.04 W g−1 assisted with 50, 55 and 60 °C inlet air temperatures) dehydration methods. The quality was assessed in terms of L∗ a∗ b∗, total color difference (ΔE), chroma, Hue angle, and rehydration capacity measurements. In addition to higher drying rate, the quality parameters for microwave-convective treatments were significantly higher than those for other methods. Drying kinetic curves indicated a constant rate period followed by a falling rate period in both convective and microwave drying methods. However, for microwave-convective treatments a falling rate period was observed with the exception of a very short accelerating period at the start. Mathematical modeling of the drying kinetics was conducted by applying the commonly used drying models to the experimental data. According to the statistical parameters, Midilli et al. model presented the best prediction for the drying kinetics.

단백질가수분해효소를 첨가한 스펀지케이크의 품질 특성

This study investigated the effect of protease on quality characteristics of sponge cake. Protease was used at levels of 0.0005 U (PC-1), 0.0010 U (PC-2), 0.0015 U (PC-3), and 0.0020 U (PC-4) for sponge cake preparation. Amylogram showed the setback was significantly decreased in comparison with the control (P<0.05). Height and baking loss rate of control sponge cake were 4.24±0.18 cm and 12.01±0.29%, respectively. PC-3 and PC-4 showed increased heights of 5.22±0.16 and 5.24±0.11 cm as well as slightly increased baking loss rates of 12.71±0.31% and 12.89 0.61%, respectively. Specific volume and color difference measurements of control showed a specific volume of 3.53±0.06 mL/g, crust color difference of 53.05±0.28, and crumb color difference of 29.84±0.52. Measurements of specific volume, crust color, and crumb color of PC-3 and PC-4 were 4.18±0.02 mL/g, 56.19±0.84, 29.05±0.43, 4.21±0.02 mL/g, 56.85±0.43, and 29.45±0.47, respectively. Firmness measurements showed that the control had the highest firmness. PC-3 and PC-4 were effective at improving the shelf-life of sponge cake as indicated by reduced firmness. Sensory evaluation results demonstrated that all samples scored higher than the control. Throughout the results, the addition of protease increased volume and improved quality characteristics of sponge cake.

Thermal degradation of natural dyes and their analysis using HPLC-DAD-MS

AbstractBerberine, palmatine, alizarin, purpurin, indigotin, and indirubin which were the major coloring compounds of Phellodendron bark, madder, and indigo plant were thermally degraded in 100°C oven in liquid dye form and also in silk dyed with five of these pigments. A mixed dye solution of six coloring compounds was prepared in DMSO solution and was thermally degraded for up to 7 days. Silk were dyed using either a mixed dye solution of five dyes or individual dye solutions and each were degraded for 7 and 14 days, respectively, and the dye was extracted from the samples for the HPLC analysis. The concentration of coloring compounds in the degraded samples were analyzed by HPLC-DAD-MS and the color difference (ΔE) of the degraded silk was examined using a spectro-colorimeter. Alizarin and purpurin were more resistance to degradation than other coloring compounds both when in solution form and in silk dyeings. And such result was verified by the color difference measurement of the degraded silk dyed with individual dye solution. The resistance of alizarin and purpurin to thermal degradation was highly likely due to the fomation of fiber-metal-dye chelated complex by alum or iron mordanting before dyeing.

Description of photochromic textile properties in selected color spaces

Research in color science includes studies on the spectral properties of light and the perception of color by the human eye and the brain. Color spaces allow the description of the position of a color by using three basic attributes, namely lightness, chroma and hue. Photochromic pigments used as a component of ultraviolet sensors can help to define color changes in time through the measurement of color differences in exposition and decay phases. The change of color can be evaluated in terms of the light source employed, reversion and the kinetics of photochromic effects. Commercial spectrometers are not suitable for this type of measurement. These instruments cannot measure the kinetics of exposure and the decay phase of photochromic materials. A unique spectrophotometer and a methodology for measuring colorimetric and spectral data of photochromic pigments in selected color spaces are presented. This work is the first step towards standardization of the measurement of color-changing materials containing functional dyestuffs, such as photochromic pigments.

Background and foreground interaction: Influence of complementary colors on the search task

AbstractLabels are indispensable visual (communication) elements that completely deliver the geospatial message of maps. The objective of this study is to investigate the impact of complementary colors between the map's background and text on the readability of cartographic texts and thus on the efficiency of the map user's search task. This is compared with the use of the “traditional” black labels on the corresponding colored backgrounds. Furthermore, a number of user characteristics, such as gender and expertise, are taken into account as well. The users' eye movements were registered to study their attentive behavior during the visual search task. In addition to the complement of the color's hue, the analyses were based on the difference in luminance, which could also affect the labels' readability. The difference between the black and colored label design was significantly different versus the eye‐tracking metrics. A correlation was found between the color difference and reaction time measurement and between the luminance difference and fixation duration. © 2014 Wiley Periodicals, Inc. Col Res Appl, 40, 437–445, 2015

Scanning Measurement of Coated Glass Color-Difference and Design of Anti-Interference

Based on the colorimetric theory and combined with the production process of glass industry, a color-difference measurement system was designed. The system was applied to online color-difference detection for coated glass. Scanning measurement of color-difference based on spectroscopy was detailed, and the technologies of light source modulation and signal demodulation synchronization were introduced into the system. This avoided using sensor masks or soft curtain to eliminate backlight interference. Under the light source with fluctuations and other background noise, the new system can get robust measurement values. The experimental results show that the anti-interference method smooths the curve of color-difference, and improves the signal-to-noise ratio. The system meets the demands of practical color-difference testing, and provides a new method for online color measurement with high accuracy.

Robust hybrid color image watermarking method based on DFT domain and 2D histogram modification

In this paper, we present a robust hybrid watermarking method applied to color images for authentication, which presents robustness against several distortions. Due to the different nature of common signal processing and geometrical attacks, two different techniques for embed a same watermark are used in this method. In the first one, the luminance component (Y) information is used to embed the watermark bit sequence into the magnitude of the middle frequencies of the Discrete Fourier Transform (DFT). In the second one, a selected region of 2D histogram composed by blue-difference and red-difference (Cb–Cr) chrominance components is modified according to the watermark bit sequence. The quality of the watermarked image is measured using the following well-known indices peak signal to noise ratio (PSNR), visual information fidelity (VIF) and structural similarity index (SSIM). The difference color of the watermarked image is obtained using the normalized color difference (NCD) measure. The experimental results show that the proposed method provides robustness against several geometric distortions, signal processing operations, combined distortions and photo editing. The comparison with the previously reported methods based on different techniques is also provided.

Influence of staining solutions and whitening procedures on discoloration of hybrid composite resins

Objectives. The aim was to evaluate the color stability and water uptake of two hybrid composite resins polymerized in two different conditions after exposure to commonly consumed beverages. In addition, the effect of repolishing and bleaching on the stained composite was evaluated. Methods. Eighty specimens (12 mm × 12 mm × 3 mm) were made from two hybrid composite resins of shade A2. Forty specimens of each composite were divided into two groups (n = 20 per each) according to the curing method used (hand light cure HLC or oven light cure OLC). Then each group (HLC or OLC) was sub-divided randomly into four sub-groups (n = 5), which were immersed for 60 days in different beverages (distal water, coffee, tea and pepsi) and incubated at 37°C. Water uptake was measured during this time and followed by measurement of color difference (ΔE) by using a spectrophotometer. After complete staining, repolishing (grit 4000 FEPA at 300 rpm under water) and bleaching (40% hydrogen peroxide bleaching gel) were conducted. The repolished and bleached specimens were submitted to new color measurements. Results. Color value of the specimens immersed in tea displayed the highest statistically significant (p < 0.05) mean color difference (ΔE) compared to other beverages, whereas the ΔE value of pepsi was significantly lower than the others. After staining of the composite resins, both the bleaching and repolishing were able to reduce the ΔE value. Conclusions. All beverages used affected the color stability of tested composite resins. The effect of beverages on color change of composites depends on type of beverage and water uptake value of resins used. A superior whitening effect was obtained with repolishing technique compared to bleaching.

Comparing Study on Translucency of Four Veneered Dental All-Ceramic Core Materials

This study aimed to compare the translucency of four veneered dental all-ceramic core materials,including IPS e.max Press,Zenostar,Lava Zirconia and Upcera Zirconia.All specimens were fabricated at 10mm in diameter and 1.00.01mm in thickness.The translucency of specimens were measured with color difference meter and measurements were statistically analysed with SPSS 13.0. Experimental results showed that their translucency had significant difference,the order of relative translucency from high to low was IPS e.max PressLava ZirconiaZenostarUpcera Zirconia.IPS e.max Press which has good optical effect may be preferable for restoring anterior tooth with higher translucent. As for relatively opaque posterior tooth,Upcera Zirconia may be advisable.

Structural and optical investigation of the effect of electron beam irradiation in a PM-355 nuclear track detector

The effect of electron beam irradiation on the structure and optical properties of a PM-355 solid-state nuclear track detector has been investigated. Samples from PM-355 were irradiated with electron beams with different doses ranging from 20 to 250 kGy. The structural and optical modifications in the electron beam-irradiated PM-355 samples have been studied as a function of dose using different characterization techniques such as Fourier transform infrared spectroscopy, Vickers hardness, refractive index and color difference measurements. The Commission International de E'Claire (CIE units x, y and z) methodology was used in this work for the description of colored samples. In addition, the color differences between the non-irradiated sample and those irradiated with different electron beam doses were calculated. The results indicate that the PM-355 detector acquires color changes under electron beam irradiation.

Use of data on color discrimination thresholds for measurement of color differences

A new method for the measurement of color differences is described. By means of the method, it becomes possible to find the shortest (i.e., in terms of color discrimination thresholds) path between two color points which in a standard non-equicontrast CIE 1931 color space is not a straight line. The method is based on local transformations of infinitely small regions of a given color space with the use of data on color discrimination thresholds obtained by interpolation or approximation of experimental data.