KR100914952B1 - Color-matching method with computer color-matching apparatus - Google Patents

Abstract

The present invention relates to a computer color matching device consisting of a spectrophotometer and a computer and a color matching method using the same. More particularly, the present invention relates to a color prescription for predicting a color combination and a compounding ratio capable of producing an unknown color in the field. (A) spectrophotometer; (B) logic and color matching calculation logic for obtaining color data corresponding to a plurality of pigment combinations of samples produced on-site and unit concentration spectral data of primary colors; (C) a method for predicting color using a computer toning device composed of a computer operating the logic, the method comprising: obtaining unit concentration spectral data of primary colors; Obtaining a reflectance or K / S curve of a target color using a spectrophotometer; And calculating a pigment combination and a prescription for obtaining the target color using unit concentration spectral data of primary colors.

Description

Prediction method of color using computer color matching device {COLOR-MATCHING METHOD WITH COMPUTER COLOR-MATCHING APPARATUS}

The present invention relates to a computer color matching device consisting of a spectrophotometer and a computer and a color matching method using the same. More particularly, the present invention relates to a color prescription for predicting a color combination and a compounding ratio capable of producing an unknown color in the field.

A color matching system using a computer measures spectra reflectance of an unknown color with a spectrophotometer and sends the reflectance data to a computer, which in advance indicates a K value (light absorption coefficient) and an S value (light scattering coefficient value) of a pigment. Logical color matching is performed on the stored data through mathematical operations. For example, US Pat. No. 3,601,589 is known, and several methods have been proposed to improve or supplement some of them.

However, the color matching method according to the method described in the above-mentioned US patent is a method of calculating a prescription by a first mathematical approximation method using data obtained from a known pigment for an unknown target color. It is often different from the target color and needs to be corrected and corrected.

In addition, the color matching method according to the method described in the U.S. patent obtains the color characteristic data of the primary color in a small amount of samples, and the color granting conditions (circulation conditions, liquid ratio, temperature distribution, etc.) Since it is greatly different from the spot dyeing, there is a problem in that the color difference is large when the spot is produced by the prescription obtained by the above method.

Since the difference in color granting conditions between the laboratory and the field is the biggest factor of color difference generation, a color matching method is required to solve this problem.

An object of the present invention is to provide a color matching method using a computer toning device that can be used in the field with high precision and minimizes the color difference generated due to the difference in color grant conditions between the laboratory and the field.

In order to solve the above problems, a combination of pigments of a target color using a unit concentration spectrum of primary dyes calculated from a sample dyed with a known pigment and concentration under the same conditions as a target color using a computer coloring device and By calculating the blending ratio, it is possible to easily obtain a pigment combination and blending ratio that can be directly applied to field production with high precision.

According to the present invention, in the dyeing process in which the dyeability difference between the laboratory and the field occurs, it is possible to easily obtain a pigment combination and blending ratio that can be directly applied to the field production with high precision.

In addition, the present invention is more effective in obtaining a dyeing prescription that can be directly applied to the field production in the continuous dyeing test and production conditions significantly different from the laboratory and the field.

1 is a process diagram schematically showing a method of prescribing color using a computer coloring apparatus of the present invention.

Figure 2 shows the unit concentration spectrum of each dye of Example 1.

Figure 3 shows the unit concentration spectrum of each dye of Example 3.

Figure 4 shows the unit concentration spectrum of each dye of Example 5.

According to a preferred embodiment of the present invention, there is provided an apparatus, comprising (A) a spectrophotometer; (B) logic and color matching calculation logic for obtaining color data corresponding to a plurality of pigment combinations of samples produced on-site and unit concentration spectral data of primary colors; (C) a method for predicting color using a computer toning device composed of a computer operating the logic, the method comprising: obtaining unit concentration spectral data of primary colors; Obtaining a reflectance or K / S curve of a target color using a spectrophotometer; And calculating a pigment combination and a prescription for obtaining the target color using unit concentration spectrum data of primary colors.

According to another suitable embodiment of the present invention, the unit concentration spectral data of the primary color pigments is obtained from a plurality of dye color combinations of samples produced in situ.

According to another suitable embodiment of the present invention, the target color is selected from various combinations of prescriptions available.

Hereinafter, the present invention will be described in detail.

The present invention (A) spectrophotometer; (B) logic for obtaining color data and unit concentration spectral data of primary colors corresponding to a plurality of pigment combinations of samples produced on-site; (C) A method of prescribing color using a computer toning device consisting of a computer operating color matching calculation logic, i) A sample dyed with a known pigment and concentration under the same conditions as the dyeing target color. Preparing (S11), ii) measuring the spectral reflectance of the sample to obtain unit concentration spectral data of primary pigments (S12), iii) obtaining a reflectance or K / S curve of the target color using a spectrophotometer ( S13), iii) calculating the color combination and the logic for obtaining the target color by color matching calculation logic using the unit concentration spectrum data of the primary color (S14), ⅴ) the color combination calculated by the color matching calculation logic and (S15) presenting a plurality of pigment combinations and prescriptions within the color difference allowed for the prescription (iii), the difference between the color data of the predictive prescription and the color characteristics of the target color and the dyeing characteristics of the predictive prescription. And the like with the prescription result (S16).

Prescription prediction method of the color of the present invention can be preferably performed for the case of dyeing the fibers by a batch dyeing device, a continuous dyeing device, a printing device and in all cases to give a color to the mixed color. .

The computer toning apparatus of this invention consists of a spectrophotometer (A), a computer calculation program (B), and a computer (C).

Spectrophotometer (A)

The spectrophotometer may use a known spectrophotometer capable of spectrometrically measuring the fiber color to measure the spectroscopic reflectance of the visible light region. The spectral reflectance should be able to obtain a wavelength range of light of at least 400 to 700 nm, and it is desirable to be able to measure the spectral reflectance in units of 20 nm or less.

Computer operation program (B)

Hereinafter, the calculation of the unit concentration spectrum of the pigment and the calculation algorithm of the prescription prediction using the same will be described.

The color K / S of the mixed color in the material reflecting light may be represented by the following Equation 1.

[Equation 1]

(K / S) _λ = k _{0 , λ} + k _{1 , λ,} f (c ₁ ) + k _{2 , λ} f (c ₂ ) + k _{3 , λ} f (c ₃ ) + + k _n , _λ f ( c _n )

Where c ₁ , c ₂ , c ₃ , ......, c _n is the concentration of pigment (i = 1, 2, 3,, n), k _{1 , λ} , k _{2 , λ} , k _{3 , λ} , ......, k _{n , λ} are unit concentrations of i dye at each wavelength λ (c _i K / S, k _{0 and λ} in = 1) are the concentration functions of K / S and f of the substrate at wavelength λ, respectively.

If Equation 1 is established at m wavelengths of all visible light regions and the substrate is white, k _{0 and λ} = 0, so the two equations can be represented by the following vector and matrix.

[Equation 2]

D = K

Here, D, K and C are as follows and the subscript T denotes a transpose matrix, and D, K and C are vector matrices as shown in Equations 3 to 5 below.

[Equation 3]

D = ((K / S) ₁ , (K / S) ₂ , (K / S) ₃ , ....., (K / S) _m ) ^T

[Equation 4]

[Equation 5]

C = (f (c ₁ ), f (c ₂ ), f (c ₃ ), ....., f (c _n )) ^T

In order to quantify the amount of pigment in a substance containing mixed pigments, therefore, K And it is necessary to know f. f can be assumed to be a linear or nonlinear relationship with concentration. Which relationship is best suited depends on the substrate, the type of pigment, and the amount used. Assuming that K knows all pigments 1, 2, 3, ...., n and that the relationship with D for concentration C is linear, Kubelka Munk is derived from the experimental relationship of D for concentration C for each pigment (i). Using Equation 6) can be obtained as in Equation 6.

[Equation 6]

k _{i , λ} = ∑ ^m _{j = 1} (k _{j , λ} c _j ) / ∑C _j ²

There are many known methods for quantifying pigment concentrations based on this principle, and the application in the laboratory shows good results when the relationship of K / S to the concentration is linear. In most cases, however, the K process is performed on a small amount of samples in a laboratory, and when applied to the mass production process, the accuracy of prescription prediction is very low.

In order to match the process of finding K with the production process, it must be obtained in the mass production process, but it is difficult to apply practically because it requires a lot of cost and effort. Therefore, the present invention devised a method for obtaining K in mass production using samples made in the production process with various known pigments and concentrations. It will be described in detail below.

In general, owner analysis and singular value decomposition may be used to extract a valid component factor from a mixture of information. However, the spectral vectors obtained from these methods differ in shape from those of the three primary colors and contain negative numbers. Since the spectral vectors of the dye at the unit concentration must all be positive, it is difficult to use the spectral vector obtained by owner analysis or singular value decomposition as the unit concentration spectrum of the dye.

The nonnegative factorization method of a matrix is to decompose a matrix composed of only positive elements as a factor having only positive elements as shown in Equation 7 below.

[Equation 7]

D (m, n) = W (m, r) · H (r, n)

This solves the problem of negative generation in the master, which has not been overcome by the factorization of the conventional matrix, and its usefulness is expected in various fields. The nonnegative factorization algorithm of the matrix, which decomposes the matrix D into W and H, finds W and H where the distance || V-WH || in Euclidean space does not increase under the following update rule conditions: .

[Equation 8]

First, the dimension of W and H is determined as following factor for applying non-negative factorization of matrix to color analysis.

m = Number of color samples

r = Number of colorants applied in the samples

n = Number of data point in the range of visible spectrum

Therefore, W is now the concentration of the dye constituting the sample, and H is the spectral vector at the unit concentration of each dye. Assuming that f (ci) = ci in Equation 1, that is, C and K / S have a linear relationship, the relationship between Equation 1 and W and H may be expressed as follows.

[Equation 9]

As shown in Equation 9, when the color spectrum is decomposed into two factors, the concentration corresponding to W is a dimensionless value, and the unit of concentration has various dimensions such as g / L, mol / L, and% concentration. It is necessary to convert the magnitude of H obtained by the law for each concentration unit. For this purpose, W should be obtained from various spectral samples made at known concentrations, and H should be corrected by ratio of known concentration and W for each pigment. (i) If the W value of the pigment is (w _ij ) and the known concentration is (c _ij ), the relationship between the two concentrations should be linear, so that the proportionality constant L _i is obtained as shown in Equation 10 below.

[Equation 10]

L _i = ∑ ⁿ _{j = 1} w _ij c _ij / ∑ ⁿ _{j = 1} / (c _ij ) ²

Where n is the number of samples. Therefore, the spectral vector H 'of the unit concentration corrected in a given concentration unit is given by the following equation (11).

[Equation 11]

H '  = L _i  H

If there is no interaction between pigments in the mixed pigment's K / S spectrum, if the spectral vector of unit concentration is K = H ', the concentration C satisfying the spectral vector D of the target sample is solved by the matrix equation You can get it.

[Equation 12]

C = K ^-1 · D

In this case, K is not a square matrix, so the inverse cannot be obtained. But KK ^T Assuming that the matrix V of eigenvectors of the eigenvectors U, K ^T K matrix and the inverse matrix K ^-1 of the orthogonal normalized them K is obtained by the following equation (13) of. T denotes the transpose matrix below.

[Equation 13]

^{K -1 = V · S -1 ·} U T

Where S ^{- 1} is a diagonal matrix with the inverse of the square root of the eigenvalues of U and V, and U ^T is the transpose of U.

In addition, another method for calculating C may use a pseudo inverse of K as shown in Equation (14).

[Equation 14]

K ^-1 = ( K ^T · K) ^-1 · K ^T

In addition, if the target spectrum D is placed in the relationship of D = C K, the concentration vector C can be obtained by performing non-negative matrix factorization (NNMF) under the condition of knowing D and K.

Computer (C)

In the computer C, a plurality of pigment combinations, color data corresponding to each of the pigment combinations, and unit concentration spectrum data for each dye required for calculating the color data are registered. The color characteristic data of the plurality of original dyes registered in the computer C may be spectral data, light source data, tristimulus data, etc. at a unit concentration of the original dye.

In addition, the computer C registers a calculation logic for obtaining spectral data of unit concentrations of the original dye from the spectroscopic reflectance data measured on a sample obtained by dyeing a plurality of dyes at a known concentration in a device to be dyed.

In addition, the computer C registers a color matching calculation logic capable of predicting the pigment blending ratio of the target color by using the dye blend and the unit concentration spectrum data of each dye.

Next, a method of predicting color prescription using the computer color matching device will be described with reference to the accompanying drawings. 1 is a process summary diagram of the present invention.

Referring to Figure 1, the color prediction method of the present invention, i) preparing a sample stained with a known pigment and concentration under the same conditions as the dyeing conditions of the target color (S11), ii) measuring the spectral reflectance of the sample Obtaining the unit concentration spectral data of the primary pigment (S12), obtaining a reflectance or K / S curve of the target color using a spectrophotometer (S13), and iii) combining and prescribing a pigment to obtain the target color. Calculating the color matching calculation logic using unit concentration spectral data of the primary pigment (S14), i) presenting a plurality of pigment combinations and prescription within the color difference allowed for the color combination and the prescription calculated by the color matching calculation logic. (S15), i) displaying the difference between the color data of the predictive prescription and the color characteristic value of the target color and the dyeing characteristic of the predicted prescription together with the prescription result (S16).

1. Preparing the sample (S11)

In this step, the color characteristic data of primary pigment | dye is acquired from the color in which the some pigment | dye was mix | blended. A plurality of samples are prepared by staining with known pigments and concentrations under the same conditions as for dyeing the target color.

2. Obtaining unit concentration spectral data of the primary color (S12)

After measuring the spectral reflectance of the sample, the unit concentration spectral data of the primary colors are calculated by the calculation logic registered in the computer (C). Calculation logic is performed by equations (1) to (11) in the "computer calculation program (B)". The spectroscopic reflectance measured at this time is converted to a spectral K / S curve, and the spectral data at unit concentrations of primary colors are stored in a computer by dividing them into groups of pigments for use as basic data for the following processes.

3. Obtaining the reflectance or K / S curve of the target color ( S13 )

In this step It is a process of obtaining the spectral reflectance or K / S curve of a target color using the spectrophotometer which is a colorimetry apparatus. It is preferable to measure the same as the method and conditions for obtaining the spectral reflectance of the step S12.

4. Color matching Calculation logic  Calculating a prescription ( S14 )

In this step, the color combination and the prescription for obtaining the color of the target color are calculated by color matching calculation logic using the color characteristic data of the primary color obtained in step S12. The calculation logic is the same as Equation 12 to Equation 14 in the "computer operation method".

5. presenting a plurality of pigment combinations and prescriptions ( S15 )

In this step, a plurality of pigment combinations and prescription groups are presented within a color difference allowed for the pigment combination and the prescription obtained as a result of the color matching calculation logic of S14. This suggests a plurality of pigment combinations and prescription groups to enable optimal selection to achieve the target color.

In the prescription group obtained in this step, the selection criteria of the optimal prescription may be cost, compatibility between pigments, metamerism according to the light source, color fastness, and the like.

In addition, this step can be made possible to deliver the prescription obtained in S14 to the electronic balance.

6. Prescription color data and target color Color characteristic  Show differences ( S16 )

In this step, the color data of the color to be dyed with the predicted prescription, the difference between the color characteristic value of the target color, the dyeing characteristic of the predicted prescription, etc. are obtained and displayed as the prescription result. The data displayed together with the prescription results include the color difference between the prescription prediction result and the target color, the difference in the metamerism index, the spectral characteristics (reflectance, K / S), the cost, the compatibility between the pigments, the predicted fastness, and the like. They can be output to monitors and printers.

Hereinafter, the present invention will be described in more detail with reference to Examples, but embodiments according to the present invention can be modified in many different forms, and the scope of the present invention is construed as being limited to the embodiments described below. Can not be done.

In each of the following examples, the measurement of the spectral data at the unit concentration of the target color and the primary colorant is performed by a spectrometer (Model 7000 and 3000, manufactured by Gretag McBeth), and the color matching calculation logic is performed by the above computer calculation program ( Executed by the program written by the algorithm described in B).

Example 1

Pad-predrying-chemical pad-sticker at four concentrations shown in Table 1 using three types of bat dyes (Olive dye = Mikethrene Olive T, Yellow dye = Indanthrene YellowF3GC, Brown dye = Indanthrene Brown ICBR) on cotton fabrics The dyeing samples were prepared by continuous dyeing by the ming method. Spectral reflectance of the dye samples was measured and the unit concentration spectral data for each dye were calculated according to the calculation logic performed by Equations 1 to 11 in the "Computer Computing Program (B)", and are shown in FIG. 2. At this time, the concentration of the dye used for each sample was the same as the target color shown in Table 1.

Example 2

Four cotton fabric target colors were pad-pre-dry-chemical pads under the same conditions as in Example 1 using three kinds of bat dyes (Olive dye = Mikethrene Olive T, Yellow dye = Indanthrene YellowF3GC, Brown dye = Indanthrene Brown ICBR) It was prepared by continuous dyeing by the steaming method. After measuring the spectral reflectances of the four target colors, a prescription that can give the same color as the target color with which the prescription is known in advance using the unit concentration spectrum data of each dye obtained in Example 1 is shown in Table 1 below.

Comparative Example 1

Table 1 shows a prescription for giving the same color as the target color under the conditions using the same dye as Example 1 by the metameric matching method shown in US Patent No. 3,601,589.

TABLE 1

According to Example 2, a prescription similar to that of a known target color can be obtained with all the prediction prescriptions within a color difference of 1.0. In comparison, Comparative Example 1 calculated a prescription that deviates greatly from the target color.

Example 3

Pad-predrying-steaming at various concentrations using four types of reactive dyes (Yellow dye = Jemical Yellow K3RS, Red dye = Jemical Red K3BS, Blue dye = Jemical Blue R, Black dye = Jemical Black EB) on cotton fabrics The dyeing samples were prepared by continuous dyeing by the method, and the unit concentration spectral data of each dye were shown in FIG. 3 in the same manner as in Example 1. At this time, the concentration of the dye used for each sample was the same as the concentration of the target color of Table 2.

Example 4

The 12 cotton fabric target colors were pad-pre-dried-stitched using four types of reactive dyes (Yellow dye = Jemical Yellow K3RS, Red dye = Jemical Red K3BS, Blue dye = Jemical Blue R, Black dye = Jemical Black EB). Using the unit concentration spectrum data for each dye obtained in Example 3 under the condition of continuous dyeing to obtain a prescription that can give the same color as the target color knowing the prescription in advance is shown in Table 2.

Comparative Example 2

U.S. Patent No. 3,601,589 Table 2 shows a prescription for giving the same color as the target color under the condition that the same dye as in Example 4 is used as the metameric matching method.

TABLE 2-1

Table 2-2

According to the fourth embodiment, a prescription similar to that of the known target color can be obtained with all the prediction prescriptions within 1.5 of the color difference. In comparison, Comparative Example 2 gives a result of calculating a prescription that deviates significantly from the target color.

Example 5

Four concentrations of acid-containing metal dyes (Yellow = Neutrilan Yellow K-3R, Gray = Irgalan Gray GLN, Navy = Lanasyn Navy S-DLN, Bordeaux = Neutrilan Bordeaux K-RL) Figure 4 shows the unit concentration spectral data of each dye obtained from the dye samples subjected to continuous dyeing by spray-steaming. At this time, the concentration of the dye used for each sample was the same as the concentration of the target color of Table 3.

Example 6

Four kinds of acidic dye dyes (Yellow = Neutrilan Yellow K-3R, Gray = Irgalan Gray GLN, Navy = Lanasyn Navy S-DLN, Bordeaux = Neutrilan Bordeaux K-RL) Using the dye-specific unit concentration spectrum data as in Example 5 under the condition of continuous dyeing using the spray-steaming method, a prescription that can give the same color as the target color of the prescribed prescription is obtained. Indicated. At this time, the target color was used for spectroscopic reflectance which averaged several times of dyeing (each sample # 1, 9 samples # 2, 4 samples # 3). The obtained prescription shows that a color characteristic value perfectly matching the target color (ΔE = 0) and a prescription matching the known target color can be calculated.

TABLE 3

According to the method of the present invention, it is possible to easily obtain a prescription that can be directly applied to the field production with high precision in the dyeing process in which the dyeability difference between the laboratory and the field occurs.

In addition, the present invention is more effective in obtaining a dyeing prescription that can be directly applied to the field production in the continuous dyeing test and production conditions significantly different from the laboratory and the field.

Claims (3)

(A) spectrophotometer; (B) logic for obtaining color data corresponding to a plurality of pigment combinations of samples produced on-site and unit concentration spectral data of primary colors and color matching calculation logic; (C) In the method of prescribing color using a computer toning device composed of a computer operating the logic, Obtaining unit concentration spectral data of primary dyes from a plurality of dye color mixtures of a field produced sample; Obtaining a reflectance or K / S curve of a target color using a spectrophotometer; And Computing a color combination and a prescription for obtaining the target color using the unit concentration spectrum data of the primary pigments. The method of claim 1, wherein the color matching calculation logic uses a nonnegative factorization method of a matrix. The method of claim 1, wherein the target color is selected from the various combinations of prescriptions available.