Estimation of dye concentration in the cross section of polyamide rod using scanner data (original) (raw)
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The problem of primary interest in quantitative analysis of a dye bath or a dyed sample of textile is to determine the concentration with a minimum percentage error. The present study describes the applicability of two reflective models i.e. the Kubelka-Munk and the Allen-Goldfinger here called Geometry, to estimate the concentration of dye from the reflectance data. The performance of the Geometry model in predicting the spectral reflectance factor of dyed polyamide fibers is evaluated by the determination of the unit k/s and the Beer-Lambert absorption extinction coefficient. To examine the models, a reflectance dataset is created by dyeing nylon 6 fabrics with four different acid dyes. The results show that the replacement of the unit k/s for the Beer-Lambert absorption coefficient in the Geometry model causes lower error in the prediction of the spectral reflectance factor. However, it is shown that this model, does not lead to better results. Consequently, the Kubelka-Munk mode...
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The classical principal component analysis technique is enhanced for reconstruction of reflectance spectra of surface colors from the corresponding tristimulus values under a given set of viewing conditions, i.e., D65 illuminant and 1964 standard observer. In this paper, the number of implemented eigenvectors has been virtually extended from three to six by estimation of another set of tristimulus values under illuminant A and 1964 standard observer. The second set of colorimetric data was predicted by the conventional non-linear regression method and used in the spectral reconstruction to produce a fully determined system in the case of six eigenvectors. The improvement obtained from the proposed modification was examined for the recovery of the reflectance spectra of Munsell color chips as well as ColorChecker DC samples. The performance is evaluated by the mean, maximum and standard deviation of color difference values under other sets of light sources. The values of mean, maximum and standard deviation of root mean square (RMS) errors between the reproduced and the actual spectra were also calculated. Results are compared with those obtained from traditional methods using the principal component analysis (PCA) routine. All metrics show that the suggested method leads to considerable improvements in comparison with the standard PCA approach.
A Novel Method for Determination of Compatibility of Dyes by Means of Principal Component Analysis
A novel method for determination of the compatibility of dyes in mixtures based on the application of principal component analysis is presented. The well known dip-test method is used to dye samples in different binary combinations of cationic dyestuffs. The spectral re-flectance of different samples of each mixture that dyed with a given set of dyestuffs by dip-test method has been measured and the corresponding K/S values are calculated. The actual dimensional properties of each mixture are evaluated by using principal component analysis technique and determination of cumulative percentage variance of the eigenvalues of proposed datasets. Ideally, the K/S spectral data of fully compatible pairs scatter around one dimension, while proportional to the degree of incompatibility of dyes in the mixture, other dimensions should be taken into account and cannot be ignored. Strong correlations are found between the calculated percentage variance and the traditional compatibility values of dyes shown by K value for cationic dyestuffs. The validity of suggested technique is also reconfirmed by normalization of spectral K/S data obtained from different dye sets.
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A disco photometer which was an optical sensing array based on multiple LEDs was constructed for colorimetric analysis. This approach has been used to analyse single dyes and dye mixtures containing up to three dye components. This techniq ue made use of the inherent well-defined LED emission band to provide selectivity for chromophors, which have equally well-defined absorbance band to give very good analytical data. The results showed that this LED array configuration could be used to reduce the complexity of data obtained from the mixtures and also improve the quality of the output.
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A scanner has been used as a low-cost instrument for measuring the colorimetric parameters of dyed nylon. The nylonfabric is dyed with madder natural dye using non-mordanting, pre-mordanting, and meta-mordanting. Then, the dyedsamples are scanned by a scanner and the RGB values of obtained image are converted to CIELab and HSL color spaces. Itis found that the scanner is able to evaluate the colorimetric characteristics of dyed samples. The obtained results are foundcomparable to the spectrophotometer results.
Mathematical Approach for the Determination of Dyes Concentration in Mixtures
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Surface Reflectance Estimation Using the Principal Components of Similar Colors
Journal of Imaging Science and Technology, 2007
The sensor response of a camera can be represented as the stimulus multiplied by the spectral distribution of an ambient illuminant, the surface reflectance of an object, and camera sensitivity. Surface reflectance is one of the most significant factors that indicates an object's color; therefore its estimation has received widespread attention. Among conventional methods for estimating surface reflectance, principal component analysis (PCA) has an advantage because it uses only one set of principal components for an entire reflectance population. There are limitations, however, in estimating all reflectance using this PCA method with only one set of principal components. In this article, an algorithm is proposed to estimate surface reflectance by using principal components determined by subgroups with similar colors, which are classified from the entire reflectance population. In order to compose a subgroup with similar colors, the Macbeth ColorChecker is utilized to obtain initial representative surface reflectance values for an entire reflectance population; then the Munsell chips are divided into subgroups with different principal components. Moreover, initial representatives have to be modified to avoid biased representations for the population because the Macbeth ColorChecker does not provide optimal representations for the entire reflectance population, even though it is evenly spaced in the CIELAB color space. Therefore, the mean value of each subgroup is used to obtain new representatives, and the new subgroups of reflectance are composed by using the Lloyd quantizer design algorithm. Then, the PCA method is applied for the principal components of the subgroup including surface reflectance. To evaluate its performance, the proposed estimation method was compared with that of a conventional three-band principle component analysis. The proposed method provided better results in its performance.
Reconstruction of reflectance data by modification of Berns' Gaussian method
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Berns' method for the synthesis of spectral reflectance curve from the tristimulus color coordinates is modified. Firstly, the Gaussian bell shape red primary is replaced with a sigmoidal one to solve the dissimilarity between the spectral curves at the end region of spectrum. Secondly, three predetermined Gaussian primaries used in the original Berns' method are replaced by the adaptive ones which their half-height bandwidths vary with the tristimulus values of the desired color. The mentioned modifications are applied for the recovery of the reflectance curves of 1409 surface colors (including 1269 Munsell color chips and 140 samples of Colorchecker SG) and also 204 textile samples. Results of recovery are evaluated by the mean and the maximum color difference values under other standard light sources. The mean as well as the maximum of root mean squares between the reconstructed and the actual spectra are also calculated. The modifications are compared with the common principal component analysis (PCA) as well as Hawkyard's methods for recovery of reflectance factor. Although the PCA leads to the best results, the modifications significantly improve the recovery outcomes in comparison with the original Berns method.