The RGB values obtained from a digital camera were employed for reconstruction of spectral data of transparent colored solutions. A capturing box was assembled, and a spectral dataset gathered from colored solutions was used for this purpose. The matrix R method was employed to reconstruct the spectral transmission from RGB data. Two different light sources i.e. fluorescent and halogen lamps, were employed to achieve two sets of camera responses. The results of spectral transmission recovery confirmed the applicability of the matrix R method by the value of 3.24% as the average of root mean square percentage errors between the actual and reconstructed spectra. The reconstructed transmissions were converted to absorbance spectra, and the concentrations of colored solutions were simply estimated by Beer's Law. The estimated concentrations were within the acceptable concentrations errors for some types of applications, such as estimating the amount of dyestuff in the dye solution.

In this study, the red-green-blue (RGB) color values of colored solutions captured from a digital camera are employed for reconstruction of spectral transmission of the transparent solutions. A capturing box is assembled and a spectral data set gathered from colored solutions prepared for this purpose. Principal component analysis (PCA), pseudoinverse, and matrix R methods are employed to reconstruct the spectral transmission of clear solutions from their RGB data. Two different illuminants are employed to achieve two sets of RGB data. According to the results, the PCA method led to inadequate accuracy when a set of RGB data and three eigenvectors are used, while results are improved by using first six basis functions. On the other hand, pseudoinverse leads to the worse results in comparison with PCA by using the first six basis functions. However, the results obtained from matrix R method shows considerable improvement in terms of the root mean square error between the actual and reconstructed spectral transmission curves. In fact, matrix R method diminishes the spectral errors in the two ends of spectrum in relation to other methods. © 2010 Society for Imaging Science and Technology. J.ImagingSci.Technol. DOI: 10.2352/J.ImagingSci.Technol.2010.54.1.010508

The weighted canonical correlation regression technique is employed for reconstruction of reflectance spectra of surface colors from the related XYZ tristimulus values of samples. Flexible input data based on applying certain weights to reflectance and colorimetric values of Munsell color chips has been implemented for each particular sample which belongs to Munsell or GretagMacbeth Colorchecker DC color samples. In fact, the colorimetric and spectrophotometric data of Munsell chips are selected as fundamental bases and the color difference values between the target and samples in Munsell dataset are chosen as a criterion for determination of weighting factors. The performance of the suggested method is evaluated in spectral reflectance reconstruction. The results show considerable improvements in terms of root mean square error (RMS) and goodness-of-fit coefficient (GFC) between the actual and reconstructed reflectance curves as well as CIELAB color difference values under illuminants A and TL84 for CIE1964 standard observer. 2009 The Optical Society of Japan

A linear interpolation method is applied for reconstruction of reflectance spectra of Munsell as well as ColorChecker SG color chips from the corresponding colorimetric values under a given set of viewing conditions. Hence, different types of lookup tables (LUTs) have been created to connect the colorimetric and spectrophotometeric data as the source and destination spaces in this approach. To optimize the algorithm, different color spaces and light sources have been used to build different types of LUTs. The effects of applied color datasets as well as employed color spaces are investigated. Results of recovery are evaluated by the mean and the maximum color difference values under other sets of standard light sources. The mean and the maximum values of root mean square (RMS) error between the reconstructed and the actual spectra are also calculated. Since the speed of reflectance reconstruction is a key point in the LUT algorithm, the processing time spent for interpolation of spectral data has also been measured for each model. Finally, the performance of the suggested interpolation technique is compared with that of the common principal component analysis method. According to the results, using the CIEXYZ tristimulus values as a source space shows priority over the CIELAB color space. Besides, the colorimetric position of a desired sample is a key point that indicates the success of the approach. In fact, because of the nature of the interpolation technique, the colorimetric position of the desired samples should be located inside the color gamut of available samples in the dataset. The resultant spectra that have been reconstructed by this technique show considerable improvement in terms of RMS error between the actual and the reconstructed reflectance spectra as well as CIELAB color differences under the other light source in comparison with those obtained from the standard PCA technique. http://www.opticsinfobase.org/josaa/abstract.cfm?URI=josaa-26-3-613

Colorimetric matching is employed under a series of virtual illuminants to produce more controllable and equalised colour-difference results under multiple illuminants. A method based on weighted principal component analysis of different artificial lights and the weighted mean is used to create a series of virtual illuminants. The weights were selected in a manner to create the virtual illuminants that benefit from the impact of a given illuminant, while the effects of other light sources on the formation of desired illuminants were also considered. The generated virtual illuminants were implemented in a colorimetric colour-matching trial. Using this method, by choosing suitable weights for different lighting conditions, more balanced colour-difference values were presented in the data set than was expected. The advantages of the suggested method were evaluated by the matching of a collection of 135 woolen samples under different virtual illuminants. http://www3.interscience.wiley.com/cgi-bin/fulltext/121659614/PDFSTART

A new technique is presented for determination of the diffusion behavior of dyes in fibrous materials. Polyamide 6.6 in filament form has been dyed with an acid dye in different temperatures and times. The microscopic images of the cross sections of dyed samples are captured and the RGB color images of the surfaces are converted to gray scale intensity data. Then, the variations of intensities within the fiber diameter, from the surface to the center of fiber, are analyzed. A linear relation is assumed between the concentration and the intensity for each pixel. The concentration-distance curves are plotted and the pseudo-diffusion coefficient of dye is predicted by using the error function relation between the normalized intensity and diffusion coefficient. According to the results, the index is constant for the samples dyed in different times and changes significantly by temperature. http://www3.interscience.wiley.com/cgi-bin/abstract/121657455/ABSTRACT

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. Key words: reflectance, spectrum reconstruction, principal component analysis, regression technique, tristimulus values http://www.springerlink.com/content/rt43346186p74j20/?p=74f27daef43147419efbf7e85e4c02c5&pi=8

In this study, the characterization of a four-color halftone printer is carried out by origami Neugebauer and n-modified Neugebauer models. According to the results, the modified Neugebauer method leads to a better outcome. Although the relation between target dot area and real dot area for a color inks are linear, the nonlinearity of target and real dot area for black ink caused some error especially in dark samples. In the n-modified Neugebauer model, the nonlinearity between real and target dot area is considered. Therefore, this model leads to a better color reproduction accuracy in comparison with the original Neugebauer model. The results showed that the modified Neugebuer method lead to better outcome. Keyword: Printer characterization, Neugebauer model, Halftone, Four color printer, Dot gain.

The retarding effect of gemini cationic surfactants in acrylic dyeing with a cationic dye (methylene blue) was studied by using UV-Vis spectroscopy. The dye adsorption rate increases with increasing temperature. The retarding action of gemini cationic surfactants is much stronger than that of the corresponding monomeric surfactants. In this work, a new empirical kinetic model based on simultaneous first and second order has been proposed. The kinetic of acrylic dyeing with a cationic dye at different temperatures and in the presence of monomeric and gemini cationic surfactants was studied by using different empirical equations. The proposed equation showed a very good correlation with experimental data in comparison to the previous ones. Keyword: Kinetic model, Acrylic dyeing, Gemini surfactants, Retarding, Cationic Dye.

A series of virtual illuminants are generated by applying weighted principal component analysis (wPCA) as well as weighted mean (wM) techniques to a set of artificial lights. The weights are selected in accordance to the importance of desired light source in control and/or matching process. In fact, the created virtual illuminants can be implemented in a colorimetric color matching trial or color control processing. In the case of color matching effort, by choosing suitable weights for different lighting conditions, more balanced color difference values under those illuminants which are presented in dataset could be expected. _ 2009 Wiley Periodicals, Inc. Col Res Appl, 34, 205 – 209, 2009; Published online in Wiley InterScience (www.interscience.wiley.com ). DOI 10.1002/col.20495 Key words: illuminants; weighted principal component analysis; weighted mean; color control. http://www3.interscience.wiley.com/cgi-bin/fulltext/122306674/PDFSTART

In this paper, at first, the chromatic adaptation transforms and the proposed methods for preparation of corresponding colors are reviewed. Then, the CIECAT02 CIE chromatic adaptation transform is used to prepare 7 pairs of corresponding color. The results show that the CAT02 model introduces a color difference error about the 4 degree of gray scale in comparison with visual assessments. In the next part, 12 corresponding color pairs from Munsell book of color have been prepared by employing a set of visual assessment test. Evaluating of CAT02 model with the prepared set shows that the performance of CAT02 is dependent on the color hue of the samples and it almost benefits from acceptable performance in the red and purple hues while performs the worst results in the yellow and orange region. KEYWORDS Chromatic adaptation transforms, Corresponding color, Visual assessment, Gray scale.

The concept of scalability of Kubelka-Munk fuction is defined and and quantitatively evaluated in different concentrations through visible spectrum using as well as statistical tools. By this analysis, the suitable wavelengths that the reflectance function still exhibit linear behavior with concentration variation are extracted. In fact, the validity of Kubelka-Munk function, which originates from the linearity of reflectance function against concentration, could be extended to higher amount of dye concentrations. Results from extended Kubelka-Munk model are compared with those obtained by using classical Beer-Lambert method and indicate to equal outputs in selective wavelengths. KEYWORDS Scalability, Kubelka-Munk Theory, Concentration Estimation

The variations in the ordering of white samples by different observers have been investigated. Twenty white samples with low to high CIE whiteness indices have been prepared and ranked by twenty two amateur observers and the variations of the viewers’ decisions in their ordering are compared. Results show a significant consistency between the observers’ assessments for the whites with low indices of whiteness. On the other hand, a large degree of disagreement has been found between the observers for whiter samples. In fact, the range of ranks assigned by viewers for each sample increases by increasing the whiteness of specimens. Distributions of assigned orders for samples are interpreted by considering the CIE whiteness as well as tinting indices. http://www3.interscience.wiley.com/journal/119421517/abstract

The reflectance factors of the polyamide rods which were dyed with different concentrations of three commercial yellow, red, and blue disperse dyes are recovered from their RGB data obtained from scanning of the cross sections of rods with the desktop scanner. The RGB data are converted to device independent XYZ tristimulus values by simple polynomial regression technique. Then, the principal component analysis (abbreviated by PCA) technique is employed for the recovery of reflectance spectra from the tristimulus values by using three different datasets, i.e. using the reflectance factors of Munsell chips, MacBeth ColorChecker SG, and a dynamic dataset prepared from the reflectance factors of dyed rods samples. The first three eigenvectors of each dataset are extracted and employed in the reconstruction process of spectral reflectance from XYZ colorimetric data. Finally, the well known Kubelka-Munk function is implemented for estimation of concentration of dye from the recovered spectral reflectance. The root mean square (RMS) errors between the reconstructed and the actual reflectance data over the visible spectrum are calculated. According to results, the RMS errors for the reflectance recovery are within the acceptable range. Error of estimation of dye concentration in the rods varies for different hues as well as concentrations and changes with applied dataset. http://www.springerlink.com/content/22r11m081217501n/

The weighted principal component analysis technique is employed for reconstruction of reflectance spectra of surface colors from the related tristimulus values. A dynamic eigenvector subspace based on applying certain weights to reflectance data of Munsell color chips has been formed for each particular sample and the color difference value between the target, and Munsell dataset is chosen as a criterion for determination of weighting factors. Implementation of this method enables one to increase the influence of samples which are closer to target on extracted principal eigenvectors and subsequently diminish the effect of those samples which benefit from higher amount of color difference. The performance of the suggested method is evaluated in spectral reflectance reconstruction of three different collections of colored samples by the use of the first three Munsell bases. The resulting spectra show considerable improvements in terms of root mean square error between the actual and reconstructed reflectance curves as well as CIELAB color difference under illuminant A in comparison to those obtained from the standard PCA method. Key words: reflectance; spectrum reconstruction; principal component analysis; weighted principal component analysis; tristimulus values http://www3.interscience.wiley.com/journal/121370246/abstract

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. http://www3.interscience.wiley.com/cgi-bin/fulltext/121546961/PDFSTART

The reflectance factors of transparent fibers, free from delustering agent, are predicted by Geometric as well as Kubelka-Munk models. Transparent fibers are simulated by a net of glass capillary tubes containing different solutions of dyestuffs. According to the results, the prediction of the reflectance factor of capillary net by Geometric model is relatively better than those obtained from Kubelka-Munk model however; the Geometric model suffers from a complex and massive computation process. Totally, the Geometric model performs better for dark transparent samples due to the ignorable internal scattering phenomena. On the other hand, the Kubelka-Munk model provides better results for light samples, where the Geometric model fails in acceptable prediction. http://journals.iut.ac.ir/eje/fullv26n2y2008p31-40.pdf

The repeatability of the recipe color can be affected by several different types of inevitable inaccuracies in the coloration process. Two of the major causes of poor target-color reproducibility are the (random) weighing and (proportional) strength errors. This article describes alternative definitions of colorant strength sensitivity and total colorant sensitivity of a dyeing recipe. The influences of the maximal colorant weighing and strength errors are taken into account in order to bring the magnitudes of the two treated types of sensitivity into a mutually realistic balance between each other. The quantifications of precision and accuracy of a color matching recipe are also developed and combined into a single-number measure of recipe quality. The listed quantities are expected to be useful in selecting the most reliable one(s) among the different formulations for the same standard color. The methods are presented for calculating numerical estimates of the newly introduced quantities. The precision and accuracy of the coloration process are investigated in laboratory experiments involving repeated dyeings. http://www3.interscience.wiley.com/journal/119818399/abstract

A new matching strategy based on the equalization of the first three principal component coordinates of sample and target in a 3D eigenvector space is stated. Two series of databases including 1269 specimens of Munsell Color Book and a virtual sample population of textile materials were selected. Their first three basis functions were extracted and considered as axes of eigenvector space. The principal component coordinates of two different collections of textile samples were determined in these spaces and considered as matching criteria. The performance of the proposed algorithm is evaluated by the color difference values under different light sources as well as the root mean square differences of reflectance curves. Results indicate some types of improvements in comparison with previous algorithms in terms of spectral as well as colorimetric accuracy. © 2007 Wiley Periodicals, Inc. Col Res Appl, 33, 10 – 18, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/col.20364 Key words: color formulation; eigenvector space; spectral space; principal component analysis; spectral matching. http://www3.interscience.wiley.com/journal/117864986/abstract

The role of dodecyltrimethylammonium bromide (DTAB) and a series of gemini cationic surfactants in the adsorption rate of methylene blue (MB) on acrylic fibres has been studied by means of TOC, UV–vis and FT-NMR spectroscopy. The influence of surfactant concentration, alkyl chain and spacer length of geminis has been investigated at different temperatures. The dye adsorption rate increases with increasing temperature, while the retarding action of gemini cationic surfactants is much stronger than that of the corresponding monomeric surfactants. There are small differences among the geminis with the same alkyl chain but with various spacer lengths. © 2007 Elsevier B.V. All rights reserved. Keywords: Competitive adsorption; Gemini surfactant; Cationic dye; Acrylic dyeing; Retarder http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6TFR-4NSWYY8-2&_user=1643783&_rdoc=1&_fmt=&_orig=search&_sort=d&view=c&_version=1&_urlVersion=0&_userid=1643783&md5=fa6e62e19d63e23c56e641d07c4cef1d

The performance of the CIE whiteness formula is evaluated visually by using the pair comparison method and compared with the new whiteness index suggested by Uchida. Twelve white samples are selected from 113 prepared white fabrics and their whiteness indices and tinting factors are calculated by CIE as well as Uchida whiteness indices. Some of the selected samples do not satisfy the CIE limitation conditions for evaluation of whiteness by this formula. Generally, the results of visual judgments show the priority of CIE formula over the Uchida index and this formula still correlate better than Uchida index with visual assessments for both in and the out of boundary white fabrics. Key Words: CIE whiteness index, fluorescent whitening agent, pair comparison method, principal component analysis, Uchida whiteness index, whiteness evaluation http://trj.sagepub.com/cgi/content/abstract/77/10/756

The look-up table (LUT) method is implemented for characterizing a four-color halftone printer. In order to create a LUT, 216 colored samples are created and their colorimetric coordinates were measured. Then, cubic interpolation algorithm is used to calculate the approximation. Because of differences in color gamut of printer and the gamut of samples, a gamut-mapping algorithm is used. The CLGB technique is used to map out of gamut colors. KEYWORDS Printer characterization, Color gamut mapping, Look-up table

Color constancy and metamerism are two phenomena that take place when the spectral power distribution of illuminant is changed. The difference between the color inconstancies of the metameric pairs is the source of metamerism. In present study, 98 actual metameric pairs were used to find the relation between these phenomena. The results showed that after parameric correction, the value of metameric index in the color difference group was equal to difference between their color inconstancy indices with acceptable approximation. The accuracy increased when the metameric indices were calculated after adaptation. KEYWORDS Metamerism, Color Constancy, Parameric Correction, Metameric Pair.

This paper presents a study of color behavior and reflectance factors of fibers in their crosssectional and longitudinal directions. In the practical field, it was demonstrated that the reflectance factors and the lightness (L*) of fibers are different in their cross-sectional and longitudinal directions and the mentioned values are higher for the lateral surface. The measurement of reflectance factors of fibers’ cross-sections showed that lightness and reflectance factors increase as fibers’ density increase in the measurement cell. A relationship was established between colors of fibers in two directions using the ratio of K/S values of yarns in cross-sectional and the longitudinal directions at different wavelengths. In the second part of this work a neural network was applied to relate the color of fibers in the mentioned directions. Results showed an excellent prediction with the later technique. Keywords: Reflectance, Tristimuluse Values, Neural Network, Kubelka-Munk, Color Difference, Textile rjta.org/download.php?paper=0&paper_id=06_2_04a

A procedure for creating efficient reflectance spectra from CIE tristimulus colour values is described using a modified linear model. By fixing certain criteria based on colour difference values, the proposed technique preliminarily selects a series of suitable samples from a main data set containing the reflectance values of a large number of different coloured samples, based on the colour specifications of a given sample. In this way, a series of different databases containing the reflectance values of confirmed samples relating to the particular samples are formed. Then, a well-known principal components linear model is applied using three basis functions. This operation yields higher cumulative variances in comparison with the original database, having the same number of basis vectors. The performance of the proposed method is evaluated using a different collection of samples and the resulting spectra show considerable improvements in terms of root mean square error as well as colour difference values under different illuminants. http://www3.interscience.wiley.com/journal/118556585/abstract

The CIECAM97s and Its revision, as a colour appearance model, were applied for a series of fabrics with different colours and depths to explain their colour appearance coordinates in similar viewing conditions. The results show that due to some modifications which expand the scale, the modified model has improved capabilities in calculating chroma. Besides, the calculations were simpler for the revised version of ClECAM97s model while the results from the two models were the same. Keywords: Colour appearance models, ClECAM97s, Textile, Colour http://journals.iut.ac.ir/eje/fullv24n2y2006p227-239.pdf

The weighted spectrophotometric color matching method with the optimum weighting to the spectrophotometric equations in each particular wavelength proportional to the viewing condition is applied for minimizing the color difference of instrumental color formulation of textile materials. The work is based on the one-constant Kubelka–Munk theory. The sensitivity of a recipe to small perturbation of deviation between the reflectance of target and matched samples in the visible spectrum is determined as the metamerism potentiality of proposed recipe. Its correlation with metamerism index was also studied for some metameric pairs. Metamerism potentialities are also appraised under several light sources by using equilibrate matching strategy. The results show that the outputs of colorimetric color matching are exactly identical with the weighted spectrophotometic match under the same viewing condition. According to the numerical results for matching of 58 target samples, there is a good statistical correlation between metamerism indices and the metamerism potentialities of each recipe. Our results show that the quantitative value of the metamerism potentiality of each recipe can reasonably predict the metamerism indices of applied formulation. © 2006 Wiley Periodicals, Inc. Col Res Appl, 31, 483–490, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/col.20261 Key words: color formulation; metamerism; color matching http://www3.interscience.wiley.com/journal/113412329/abstract

This paper describes the representation of the total radiance factor of fluorescent whitening agents by up to three basis components. Applying the dimensionality reduction technique to the total radiance factor of 84 cotton samples treated with different fluorescent whitening agents, it was possible to reconstruct the spectral behavior of specimens by using a very small number of basis functions, accurately. In order to study the properties of the basis function, a three-dimensional Euclidean spectral space was implemented to represent the samples. The orientation of the samples that confirmed the whiteness index limitations of CIE1982 were along a line in this space, as expected from a set of white specimens. The perfect correlation was also found between the CIE1982 whiteness index, W, and the first derived principal component coordinates of the samples. Key words: principal component analysis, fluorescent whitening agent, total radiance factor, dimensionality reduction, spectral space, whiteness index http://trj.sagepub.com/cgi/content/abstract/76/3/197

A procedure for an efficient recovering of reflectance spectra of Acrylic paint samples from CIE tristimulus color values is described. By fixing a certain criteria based on color difference value, the proposed technique preliminarily selects a series of suitable samples from a main dataset containing the reflectance values of a series of different Acrylic paint samples, based on the color specifications of given samples. In this way, a series of different databases could be formed around a particular sample. The well-known principal-components linear model was used to recover the spectral data from their corresponding color coordinates by using only 3 basis functions. The surface spectra of a set of 2802 samples are collected for the recovery of the reflectance values of Acrylic paint samples whose tristimulus values were known. The role of the value of color difference for selecting suitable samples is discussed. The recovered spectra achieved by this method show considerable improvements in terms of root mean squarer (RMS) error and goodness-fitting coefficient as -well as color difference values under different illuminants as compared to the recovery from the main database. KEY WORDS: Reflectance, Acrylic paint, Principal component analysis, Spectral estimation, Tristimulus values. http://www.ijcce.ac.ir/IJCCE/DetailArticleP.asp?Volume=25&Number=2&Ordered=5

The preliminary experiments were carried out for investigating the effect of lightness of achromatic background (white, grays, and black) on color appearance attributes (lightness and colorfulness) of some colored fabrics. A series of achromatic backgrounds at eight levels of lightness was provided. Each test color was viewed against these backgrounds and the perceived lightness and colorfulness were evaluated by using the pair comparison method. The results indicated that the lightness of achromatic background affects perceived lightness and colorfulness. The lightness of tests colors increases when surrounded by dark backgrounds while a consistent trend was not noticed for perceived colorfulness. The results from visual assessment were compared with the predicted results by the CIECAM97s model. The predictions of the model were in agreement with the perceived lightness by visual assessment but there was not any correlation between the results of model and visual assessment for colorfulness. In the second part of the experiments, a colorimetric match of samples on different backgrounds was carried out by visual judgments as well as implementation of color appearance models in reverse mode. Results from visual trials were significantly different from those predicted by the models. © 2006 Wiley Periodicals, Inc. Col Res Appl, 31, 133–141, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/col.20190 http://www3.interscience.wiley.com/journal/112396203/abstract?CRETRY=1&SRETRY=0

In this paper, the spectral transmittances of different solutions of different dyes in water are reconstructed by their colorimetric data measured by scanner. Different solutions were prepared and their RGB data were measured by scanner. Then, by using principle component analysis technique, the eigenvectors and eigenvalues of different sets of solutions were calculated, using RGB data and a linear modeling. Finally, the transmission behavior of each solution is predicted by using the basis function and the RGB values of desired solution. Although the results depend on the sampling technique, but very successful reconstructions are observed, totally. Keywords Principal Component Analysis, Transmittance Spectra, Scanner, Color Coordinates

A Basic form of the Kubelka-Munk equation is applied to simulate the reflection behaviour of tertiary blends of pre-color fibre without any limitation on the number of primaries. Similar to binary blends, the mechanism consists of two simultaneously independent processes. Firstly, the subtractive colour mixing of fibres provides a number of colour dots on the surface of samples. Then, the portative colour mixing of these dots produce the final observed or measured colour. The number of the created colours depends on the number of layers that are necessary to produce an opaque media. An increase in the fibres' transparency leads to an increase of the number of colour dots on the surface. The probability of each colour existence depends on the percentages of fibres in blends. Nine layers are considered to provide the media for applying the basic form of the Kubelka-Munk equation due to the processing power of the accessible computer. The media is still translucent in some wavelengths and needs more layers to produce completely opaque substrate. The reflectance values of samples are determined by using this model as well as the Two Constant Kubelka-Munk theory. However, in comparison to the actual reflectance values of the blended samples, the results show that two constant theory leads to smaller error. Keywords Kubelka-Munk, Reflection Prediction, Blending of Coloured Fibres, Two Constant Colour Matching.

In the present work, reflectance values of acrylic fibers along their length and cross-section were predicted using a geometric model and its modified shape. Experimental and theoretical results were compared and the possibility of applying the model for predicting the reflectance value of fibers with different finesse and colour was investigated. To fulfill the requirements of theoretical work, an existed geometric model, which has been presented to predict the reflectance value along fiber length, was employed also, because of different geometric orientation of fibers in cross-section, the model was modified to explain cross-sectional optical behaviour of fibers. Considering only three factors of surface reflectance, absorption and widthwise transmission of light and not including lengthwise light transmission in the preliminary model, may lead to obtaining unreal cross-sectional reflectance values. The results showed that the output of the model and its modified shape is almost acceptable although the increase of transmitted material in fibers and high reflectance cause a difference between theoretical and experimental results. Keywords Prediction – Reflectance Values – Geometric Model – Acrylic Fibers

Dyeing behaviour of chitosan pretreated cotton fabric with reactive dyes is the subject of this study. Cotton fabric is treated with chitosan using five different techniques, consisting of exhaustion, pad-dry, pad-batch, pad-steam and pad-dry-steam methods. To find the influence of concentration of chitosan on the dyeability behaviour, different amounts of chitosan were used and the suitable concentration was determined. It is observed that chitosan pretreatment increases the exhaustion of reactive dyes and the highest dye up-take is achieved for pad-dry method. The effect of the period of storage of chitosan treated sample before dyeing process on dyeability of fabrics is examined by comparison of samples which was dyed immediately after treatment with the one which was kept for 48 h after treatment. The results show that dyeing immediately after treatment leads to higher dyeability and the effect of treatment decreases for the samples which were kept for 48 h before dyeing process. The light and wash fastnesses of treated samples are measured and some reduction in light and wash fastnesses were observed.

In the present work the reflection behavior and the color appearance of acrylic yarns, as pile yarns used in carpet and piled fabrics, are considered along their lengths as well as their cross -sections. Differences between longitudinal and cross — sectional reflection behaviors of yarns are measured in different yarn densities and hues and explained by the geometric model The results of experimental work show that the average of reflectance and lightness values along yarns' length, with identical hue, are higher than values obtained from their cross – section. Besides, the lightness values of cross - sectional of samples, with identical hue, increase when the density of yarns in holder cell increases. The metric chromas as well as the hue angles of samples, dyed with the same dyestuff are different in two directions and lead to color difference values between 3.35 and 2 7.84 under D65 Illumination and CIE 1964 standard observer in CIELAB color difference formula. The reflection differences between two directions are analyzed using the geometric model ond it is found that they originated from different optical passes through the fibers in the mentioned modes. Keywords: Reflection behavior, Geometric model, Acrylic yarn http://journals.iut.ac.ir/eje/fullv21n2y2003p167-180.pdf

The color of the blends of pre-colored fibers depends on the ratio of each fiber in the blends. Some theories have been introduced for color matching of blends of pre-colored fibers. Most however, are restricted in scope and accuracy. Kubelka and Munk presented the most applicable theory, which is still used in industry. In this work, the classical Kubelka-Munk method for color prediction of a series of grays, prepared from different ratio of black and -white is compared with new technique, which apply neural networks. Thirteen different blends with different ratio of virgin and black fibers were prepared. The reflection of samples was measured and then a two layers network was designed. The modified back-propagation learning strategy was applied. The Sum of Squares Error was calculated for evaluation of methods. Results showed better prediction for networks in comparison to Kubelka-Munk algorithm. Key Words Color Matching, Pre-colored Fibers, Neural Network, Blend

A neural networks is employed to predict the concentrations of three primary dyes. The CIELAB colour order system is used to explain the colour of targets and samples. In order to speed the processing, two techniques are used. Firstly, the patterns are selected according to the colour coordinates of target. Secondly, the common back propagation learning algorithm is modified. The suggested concentrations by networks are tried practically and the colour difference values (AE) in CIELAB colour order system under D65 standard illuminant and 10° standard observer are calculated. The average AE is 1.27for 50 arbitrary targets. Key Words - Neural networks, colour measurement, color physics, recipe prediction, colour matching

Firstly, the effect of microwave irradiation as a pre-treatment process on enzymatic hydrolyzing of cotton fabrics is investigated. Although the exposed samples exhibited some decreasing in their tensile strength, the weight loss of these samples did not show significant differences in comparison with the corresponded control samples. In the second part of the work, the samples were hydrolyzed by cellulase or by applying of acidic buffer under microwave irradiation. In order to evaluate the results of this type of hydrolyzing on the physical properties of substrate, some samples were similarly hydrolyzed by normal heating in Ahiba Polymat, Ahiba Texomat and hot water bathes. Results show that the microwave irradiation only plays a heating effect in hydrolyzing process and this type of resonating heating method is not able to denatured the cellulase enzyme. Key words Biopolishing, Microwave Irradiation, Enzymatic hydrolysis, Cellulase, Cotton Fabric.

Damages resulting by micro-organisms on Iranian cotton (Sahel variety) with 65-70% relative humidity and 25 °C temperature within four months storage period are investigated. A number of tests are currently available to identify and quantify such cottons called cavatomic. These tests include pH and reducing sugar determinations, microscopy techniques, staining methods and determination of physical changes. Some of these tests have been applied to evaluate possible microbial damage to cotton of Gonbad-Ghabous spring crop. The effects of the micro-organisms growth on the whiteness and dye-ability of different samples are also determined. Data and observations totally support the slow growth of the micro-organisms in this variety of cottons. Key Words: Iranian cotton, microbial damage, cavatomic cotton, physical and chemical properties of cotton

This paper presents a study of color mixing behaviour of masterbatch pigments in mass dyed synthetic fibers. One / Two Constant Kubelka - Munk theories were employed to predict the targets by using some masterbatch pigments as primaries. Some modifications were applied in the calculation of absorption and scattering coefficients in Two Constant theory. In order to avoid negative or imaginary values for K and S coefficients, the Walowit and his coworker's suggested method for determination of mentioned coefficients, was modified in this research. It was found that One and Two Constant theories showed equal color difference values. Moreover, one Constant theory is better than Two Constant theory regarding dye selection.

The proposed algorithm suggests a new method for determination of K/S value of primaries based on linear Least Squares Technique. By applying the matrix pseudo-inverse, a modification is introduced to eliminate the limitation on the numbers of applied dyes in one - constant Kubelka-Munk theory. The selection of dyes for tristimulus matching are also done on the basis of the initial spectrophotometric results. The applicability of suggested methods is tested through a computer colour matching attempt with more/less than three primaries. http://journals.iut.ac.ir/eje/fullv17n1y1998p187-196.pdf

an algorithm is suggested for implementation of unlimited primaries in two-constants Kubelka-Munk color matching attempt.Allen's method for tristimulus color matching, which was limited to four colorants in two constant theory, dealt with inversable matrices. By application of the pseudo-inverse, it is not necessary to limit the number of primary colors to four as Alien suggested. The suggested method is programmed to a color matching attempt with five pre-colored fibres. http://journals.iut.ac.ir/eje/fullv14n2y1996p13-20.pdf

Some suggestions are presented in this paper for optimizing color matching in blends of pre-colored fibers. The proposed algorithm suggests an initial spectrophotometric trial for color matching with all selected colored fibers. If the initial spectrophotometric match docs not satisfy the colorimetric conditions, the data will be applied in a later colorimetric attempt. In that attempt, by applying the pseudoinverse algorithm in the iterative process, it is not necessary to limit the number of colored fibers to four, as Allen suggested for the two-constant theory.

A simulation model has been developed for the analysis of unlevelness in loose stock. The proposed model has shown that two quite different problems can arise from this kind of unlevelness, viz. mismatching and colour broken effects. For pale shades, acceptable colour tolerances and solid colours are achievable, even for unlevel dyeings, after later blending processes. On the other hand, for dark shades, elimination of the unlevelness is not as easy because of the effect of both colour tolerance and colour broken effects.

A method for the reduction of the quenching effects of fluorescent whitening agents (FWAs) on textiles has been investigated. The total radiance factors of different samples which were produced by normal after-treatment of coloured fibres were compared with a series of blends of coloured and FWA treated fibres. The higher brilliancy of the blended series indicates lower quenching effects of the FWAs in the blended samples. In spite of higher shade changes in the blended series no other side effects, such as colour broken effects, were observed in the blends in comparison with the normally treated samples.

A basic form of the Kubelka-Munk equation is proposed to explain the color be-havior of blends of precolorcd fibers. For blends of fibers the textile industry commonly uses, which arc not completely opaque, the color mixing mechanism consists of two independent processes acting simultaneously. According to the Kubelka-Munk theory for blended fibers as a translucent medium, among other parameters, the reflectance of each point on the surface is a function of the reflectances of the lower layers. This part of the color mixing mechanism is described by the law of subtractive color mixing that results from the multitude of colored dots formed by the different configurations of the fibers, from which their reflectances can be determined by the basic form of Kubelka-Munk theory. The number of these different colored dots is a function of the number of layers that are necessary to produce an opaque substrate. An increase in the fibers' translucency leads to an increase of the number of these colored dots. For fibers of the same diameter, the probability of the existence of points with a specific reflectance depends on the percentages of fibers in the blend. When this surface is viewed from a distance, the colored dots, like the dots on the screen of a color television set, mix spatially by averaging. Thus a combination of subtractive and partitive color mixing is taking place for blends.

This book is intended to provide in a single volume comprehensive text on those aspects of color science that are important to the postgraduate students and color technologists by a new learning language which emphases on examples, exercises and numerical analysis. The book is presented as a teaching text and the authors believe to the success of this learning style for the students of engineering departments. However, the basic knowledge of color science is needed for understanding of subjects. Each of the eight chapters can be read alone but there are some intentionally overlaps in some chapters to better clarify the subjects. Chapter 1 deals the principal of color matching and reviews the major aspects of colorimetry, briefly. The color difference formulas are discussed in Chapter 2 for simple samples such as textile and complex scene like images. Finally in this chapter, the industrial shade sorting methods are presented. Chapter 3 presents the mathematics of computerized color matching and the related theories. The practical nature of this chapter makes it more attractive for those who are interested in empirical subjects. Detailed discussion of fluorescent dyes and the whiteness indexes of fluorescent whitening agents are presented in Chapter 4. The metamerism phenomena and some related topics such as color constancy as well as the chromatic adaptation transforms are presented in Chapter 5. Chapter 6 deals with a very interested subject which known as spectral data processing. The application of principal component analysis technique in the spectral domain is fully discussed in this chapter. Application and characterization of new color measurement as well as color reproducing instruments are talked in Chapter 7. Trying of this chapter is emphasizes for postgraduate students in different field of science, applied science and technology. The last chapter discusses at the color appearance models and its applications in the world of multimedia. Study of this chapter is recommended for those which are interested in measuring color in complicated surround. Understanding the examples and solving the exercises needs to know computer programming. The required data are presented in the form of Matlab M files and are presented in enclosed compact disk.