Gradient-optimized spot-color ink color matching method and gradient-optimized spot-color ink color matching system

Abstract

The invention provides a gradient-optimized spot color ink color matching method and system, and belongs to the technical field of printing, the gradient-optimized spot color ink color matching method comprises the following steps: S1, preparing a plurality of base ink samples with different concentration gradients; s2, preparing the base ink sample into a color display sample sheet, and preparing a color sample corresponding to the base ink sample; s3, measuring spectrum data of each color sample through spectrum detection equipment; s4, based on the spectral data, performing first screening on the database building samples by analyzing a spectral change rule to obtain initial sample points; s5, based on the initial sample points, analyzing the linear relation between the color intensity and the concentration of the initial sample points, performing secondary screening, and selecting two sub-samples; s6, calculating the optical constant of the base ink by using the sub-samples screened out for the second time; and S7, constructing a corresponding base ink database according to the optical constants for spot color ink color matching. In the printing process, for the needed target color, the optical constant can be used for reversely deducing the base ink, labor can be reduced, and efficiency and color matching accuracy can be improved.

Description

Technical Field

[0001] This invention belongs to the field of printing technology, specifically relating to a gradient-optimized spot color ink matching method and system. Background Technology

[0002] Ink color matching is a crucial step in printing production, referring to the process of accurately reproducing the target color specified by the customer by mixing base inks in different proportions. Traditionally, this relied heavily on the experience and visual judgment of the ink mixing technician, resulting in low efficiency, poor consistency, and significant material waste. Modern computer-aided color matching systems, however, establish an optical database of base inks and use colorimetric theory for scientific calculations to quickly predict the base formula that achieves the target color. This significantly improves color matching efficiency, accuracy, and repeatability, making it one of the core technologies for realizing digital and intelligent printing production.

[0003] The high precision of existing computer color matching systems heavily relies on the completeness of their base ink databases. However, the construction of these databases still follows a crude and time-consuming model: dozens of base ink samples with extremely fine concentration gradients must be manually prepared and measured to obtain their complete spectral data. This "massive sample accumulation" strategy directly results in a huge workload, long processing time, and the consumption of large amounts of ink and substrate materials during database construction. This not only creates significant pressure on human and material costs but also becomes a core bottleneck restricting the rapid deployment and application of color matching systems. In particular, the construction of databases for multiple base ink varieties and multiple substrates becomes economically and temporally unsustainable, ultimately greatly limiting the efficiency and flexibility of this advanced technology's adoption within the industry.

[0004] Therefore, to solve the above problems, it is necessary to provide a gradient-optimized spot color ink matching method and system. Summary of the Invention

[0005] The purpose of this invention is to provide a gradient-optimized spot color ink matching method and system, which aims to solve the problem that in the prior art, dozens of base ink samples with extremely fine concentration gradients are manually prepared and measured to obtain their complete spectral data, resulting in significant labor and material cost pressures and affecting efficiency.

[0006] To achieve the above objectives, the present invention provides the following technical solution:

[0007] A gradient-optimized spot color ink matching method includes the following steps:

[0008] S1. Prepare multiple ink samples with different concentration gradients;

[0009] S2. Prepare color samples corresponding to the base ink samples by making color development sheets from the base ink samples;

[0010] S3. Measure the spectral data of each color sample using a spectral detection device;

[0011] S4. Based on spectral data, the initial sample points are obtained by analyzing the spectral variation patterns to perform the first screening of the library samples.

[0012] S5. Based on the initial sample points, analyze the linear relationship between color intensity and concentration, and perform a second screening to select two sub-samples.

[0013] S6. Calculate the optical constants of the base ink using the sub-samples selected in the second screening.

[0014] S7. Construct a corresponding base ink database based on optical constants for spot color ink matching.

[0015] Preferably, S1 includes:

[0016] S11. Select the base ink of the desired color;

[0017] S12. Mix the base ink and diluent in different mass ratios to prepare base ink samples of various concentrations in a gradient.

[0018] S13. Record the sample numbers of each concentration of base ink.

[0019] Preferably, S2 includes:

[0020] S21. After stirring each base ink sample evenly, use a colorimeter to develop the color on the same substrate to prepare corresponding color samples;

[0021] S22. Based on the sample number of each concentration base ink sample, assign corresponding sample numbers to its color samples.

[0022] Preferably, S3 includes:

[0023] S31. Obtain the spectral reflectance R of each base ink sample using a spectral detection device. i ;

[0024] S32. Collect the spectral reflectance of each base ink sample color sample;

[0025] S33. Obtain the spectral reflectance R of the substrate using a spectral detection device. P .

[0026] Preferably, S4 includes:

[0027] S41. Extract the reflectance value R of each base ink sample at the main absorption wavelength λ. λ ;

[0028] S42. Use the forward difference method to calculate the derivative values ​​of discrete data points;

[0029] S43. Find the base ink sample color sample that is the "turning point" of the reflectance change trend;

[0030] S44. Perform the first screening to obtain initial sample points.

[0031] Preferably, S5 includes:

[0032] S51. Extract the reflectance value at the main absorption wavelength of each initial sample point and the corresponding concentration of each initial sample point;

[0033] S52. Calculate the linear relationship between color intensity and concentration using the K / S value.

[0034] S53. Plot the relationship between concentration and K / S value, and perform linear fitting;

[0035] S54. Find the two initial sample points that are closest to the fitted line and call them subsamples.

[0036] Preferably, S6 includes:

[0037] S61. Construct a matrix equation based on the K / S values ​​of the two sub-samples;

[0038] S62. The optical constants Z1 and Z2 of the base ink are calculated.

[0039] Preferably, in S7, a base ink database corresponding to the base ink sample can be constructed using optical constants Z1 and Z2;

[0040] By selecting base ink samples of different colors and using steps S1 to S6, a base ink database consisting of optical constants for the corresponding base ink samples can be obtained.

[0041] A gradient-optimized spot color ink matching system, comprising:

[0042] The sample preparation module is used to prepare multiple base ink samples with different concentration gradients and prepare corresponding color samples;

[0043] A spectral measurement module is used to measure the spectral data of each of the base ink sample color samples;

[0044] The sample optimization module, based on spectral data, performs a multi-stage screening process, including first and second screening, to select key sub-samples from all samples.

[0045] The database construction module calculates the optical constants of the base ink samples based on the data of the sub-samples and constructs a base ink database for color matching.

[0046] Preferably, the sample optimization module includes:

[0047] The initial screening unit is configured to perform the first stage of sample screening based on the trend of spectral data as concentration changes, in order to determine the inflection point of reflectance change;

[0048] The fine screening unit is configured to perform a second-stage sample screening based on the linear relationship between sample concentration and color intensity function values, in order to select the most representative subsamples.

[0049] Compared with the prior art, the beneficial effects of the present invention are:

[0050] 1. This invention ensures efficiency through the first screening, avoiding ineffective investment in high-concentration areas, and ensures accuracy through the second screening, guaranteeing that the selected sample is the "optimal solution" for describing ink characteristics, thereby improving overall efficiency. It eliminates the need to manually prepare and measure dozens of base ink samples with extremely fine concentration gradients to obtain their complete spectral data. In printing, for the desired target color, the required concentration of base ink can be deduced from the corresponding optical constant to obtain the desired color, reducing manual labor and improving accuracy and precision by reducing the error of color matching based on base ink deduced from optical constants. Attached Figure Description

[0051] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used in conjunction with embodiments of the invention to explain the invention and do not constitute a limitation thereof. In the drawings:

[0052] Figure 1 This is a schematic diagram of the overall process of the present invention;

[0053] Figure 2 This is a flowchart illustrating step S4 of the present invention;

[0054] Figure 3 This is a flowchart illustrating step S5 of the present invention;

[0055] Figure 4 This is a graph showing the linear relationship between the base ink concentration and the K / S value of the present invention. Detailed Implementation

[0056] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0057] The high precision of existing computer color matching systems heavily relies on the completeness of their base ink databases. However, the construction of these databases still follows a crude and time-consuming model: dozens of base ink samples with extremely fine concentration gradients must be manually prepared and measured to obtain their complete spectral data. This "massive sample accumulation" strategy directly results in a huge workload, long processing time, and the consumption of large amounts of ink and substrate materials during database construction. This not only creates significant pressure on labor and material costs, affecting efficiency, but also becomes a core bottleneck restricting the rapid deployment and application of color matching systems. In particular, the construction of databases for multiple base ink varieties and multiple substrates becomes economically and temporally unsustainable, ultimately greatly limiting the efficiency and flexibility of the advanced technology's adoption within the industry.

[0058] Please see Figures 1 to 3 The present invention provides the following technical solution: a gradient-optimized spot color ink matching method, comprising the following steps:

[0059] A gradient-optimized spot color ink matching method includes the following steps:

[0060] S1. Prepare multiple ink samples with different concentration gradients;

[0061] S2. Prepare color samples corresponding to the base ink samples by making color development sheets from the base ink samples;

[0062] S3. Measure the spectral data of each color sample using a spectral detection device;

[0063] S4. Based on spectral data, the initial sample points are obtained by analyzing the spectral variation patterns to perform the first screening of the library samples.

[0064] S5. Based on the initial sample points, analyze the linear relationship between color intensity and concentration, and perform a second screening to select two sub-samples.

[0065] S6. Calculate the optical constants of the base ink using the sub-samples selected in the second screening.

[0066] S7. Construct a corresponding base ink database based on optical constants for spot color ink matching.

[0067] S1 includes:

[0068] S11. Select the base ink of the desired color;

[0069] S12. Mix the base ink and diluent in different mass ratios to prepare base ink samples of various concentrations in a gradient.

[0070] S13. Record the sample numbers of each concentration of base ink.

[0071] For example, using Yinfeng Red base ink, ink samples of the same mass but different ratios were prepared by adding different proportions of diluent. The specific formulations are shown in Table 1. The ink sample numbers are denoted as i, i = 1, 2, ... 19, the preparation amount is 10g, and the weighing accuracy is 1mg. The concentration ratio of the base ink in each ink sample is denoted as set C, C = {C...} i The diluent used is 75% alcohol.

[0072] Table 1:

[0073]

[0074] By reducing the proportion of diluent and increasing the proportion of Yinfeng Red base ink, 19 different concentrations of base ink samples can be obtained. In actual use, the ratio of base ink to diluent can be adjusted according to needs. For example, changing the change from 5% to 2% can improve the accuracy of subsequent tests.

[0075] S2 includes:

[0076] S21. After stirring each base ink sample evenly, use a colorimeter to develop the color on the same substrate to prepare corresponding color samples;

[0077] S22. Based on the sample number of each concentration base ink sample, assign corresponding sample numbers to its color samples.

[0078] After the ink sample is thoroughly mixed, a color developer is used to develop the color on the substrate to obtain color samples of each concentration ratio of the base ink. The sample numbers are recorded as i, i = 1, 2, ... 19. The purpose of keeping the numbers consistent with the ink sample numbers is to directly and clearly know which concentration of base ink the color sample corresponds to, which facilitates subsequent operations.

[0079] S3 includes:

[0080] S31. Obtain the spectral reflectance R of each base ink sample using a spectral detection device. i ;

[0081] S32. Collect the spectral reflectance of each base ink sample color sample;

[0082] S33. Obtain the spectral reflectance R of the substrate using a spectral detection device. P .

[0083] The spectral detection equipment can be the XriteCi64 spectrophotometer, which is existing technology and will not be described in detail here.

[0084] The spectral reflectance R of each base ink sample was obtained using a spectral detection device. i Let R be the set R = {R1, R2, R...} 19}, where Ri In the case where i = 1, 2, ..., 19, R i This represents the spectral reflectance value of the color sample corresponding to i.

[0085] like Figure 2 As shown, S4 includes:

[0086] S41. Extract the reflectance value R of each base ink sample at the main absorption wavelength λ. λ ;

[0087] S42. Use the forward difference method to calculate the derivative values ​​of discrete data points;

[0088] S43. Find the base ink sample color sample that is the "turning point" of the reflectance change trend;

[0089] S44. Perform the first screening to obtain initial sample points.

[0090] Construct a set of spectral reflectance R at the principal absorption wavelength λ of the sample number i and the base ink sample color sample. λ Form a set of discrete data points (i, R) iλ ), where R iλ This represents the spectral reflectance value at the main absorption wavelength λ of the base ink sample color sample corresponding to i. The derivative value of the discrete data points is calculated using the forward difference method and denoted as dR / di. The main absorption wavelength λ is obtained through the spectral peak, which is a current technique and will not be elaborated further.

[0091] The calculation formula is:

[0092] dR / di=(R i+1λ -R iλ ) / (i+1-i)

[0093] The derivative values ​​of each discrete data point are recorded as shown in Table 2.

[0094] Table 2:

[0095]

[0096] Record the sample number P that first appears with a "+" symbol. The set of color samples i > P is denoted as j, and the initial screening sample set is denoted as ij. For example, in the above case P = 9, so after removing color samples numbered 10 to 19, the initial screening sample set is ij = (1, 2, ... 9).

[0097] The negative sign "-" means R i+1λ <R iλ That is, as the concentration increases, the reflectance decreases and the color becomes darker, which is normal. The positive sign "+" means R i+1λ >R iλThat is, as the concentration increases, the reflectivity does not decrease but increases instead, which does not conform to the logic of the color becoming darker. This is usually due to abnormal fluctuations caused by measurement noise, scattering effect or color saturation. This can improve the authenticity and accuracy of the acquired data.

[0098] like Figure 3 As shown, S5 includes:

[0099] S51. Extract the reflectance value at the main absorption wavelength of each initial sample point and the corresponding concentration of each initial sample point;

[0100] S52. Calculate the linear relationship between color intensity and concentration using the K / S value.

[0101] S53. Plot the relationship between concentration and K / S value, and perform linear fitting;

[0102] S54. Find the two initial sample points that are closest to the fitted line and call them subsamples.

[0103] Through the formula: The calculated value (K / s) at the maximum absorption wavelength of the sample in the sample set denoted as ij. i-jλ Values ​​were used to construct a set of base ink concentration ratios and base ink sample color sample values ​​(K / S) corresponding to sample numbers ij. i-jλ The discrete data points [C] i-j (K / S) i-jλ The least squares linear fit was then performed on it to obtain the fitted curve y = kC. i-j +b, such as Figure 4 As shown, based on the above data, y = 0.2601C is calculated. i-j -0.5681, where the solid line represents the linear relationship between theoretical concentration and K / S value, and the dashed line represents the linear relationship between actual concentration and K / S value.

[0104] Through the formula: The two discrete data points closest to the linear fit are calculated and denoted as the subsamples of the second screening. The corresponding sample numbers are denoted as w and v. The purpose of selecting the two discrete data points closest to the linear fit as subsamples is to improve the accuracy of subsequent calculations of optical constants Z1 and Z2, and to reduce color matching errors when matching the required colors using optical constants Z1 and Z2.

[0105] The first screening ensured efficiency and avoided ineffective input in high-concentration areas, while the second screening ensured accuracy, guaranteeing that the selected samples were the "optimal solution" for describing ink characteristics and improving overall efficiency.

[0106] S6 includes:

[0107] S61. Construct a matrix equation based on the K / S values ​​of the two sub-samples;

[0108] S62. The optical constants Z1 and Z2 of the base ink are calculated.

[0109] Construct a matrix equation based on the K / S values ​​of sample numbers w and v:

[0110] A = [C w C v ]

[0111]

[0112] Through the formula: Z=(A T A) -1 A T B, solve for it, where and These represent the K / S values ​​at all wavelengths for the two sub-samples, respectively. Calculated, through The K / S values ​​at all wavelengths of the substrate are calculated. The K / S values ​​at all wavelengths of the two subsamples are subtracted from the K / S values ​​at all wavelengths of the substrate to obtain the K / S values ​​belonging only to the ink of the subsample. The purpose is to avoid the substrate affecting the subsequent calculation of optical constants and to further improve accuracy.

[0113] Therefore, we can solve this using a linear equation in two variables: (K / S) w =Z1·C W +Z2, (K / S) v =Z1·C v +Z2 is used to calculate the optical constants Z1 and Z2. This yields the "color fingerprint" or "code" of the Yinfeng Red base ink, i.e., the relationship between concentration and color. When matching colors in subsequent processes, the computer can use this "code" to deduce the required concentration of base ink for mixing the target color of Yinfeng Red. This eliminates the need for manually preparing and measuring dozens of base ink samples with extremely fine concentration gradients to obtain complete spectral data, reducing manual labor and improving efficiency.

[0114] In S7, a base ink database corresponding to the base ink sample can be constructed using optical constants Z1 and Z2;

[0115] By selecting base ink samples of different colors and using steps S1 to S6, a base ink database consisting of optical constants for the corresponding base ink samples can be obtained.

[0116] A database of base inks based on optical constants is constructed for different colors. In this way, when printing, the required concentration of base ink can be determined by using the corresponding optical constants to mix the desired target color. This eliminates the need to manually prepare and measure dozens of base ink samples with extremely fine concentration gradients to obtain complete spectral data, which can effectively improve work efficiency.

[0117] A gradient-optimized spot color ink matching system, comprising:

[0118] The sample preparation module is used to prepare multiple base ink samples with different concentration gradients and prepare corresponding color samples;

[0119] The spectral measurement module is used to measure the spectral data of each base ink sample color sample;

[0120] The sample optimization module, based on spectral data, performs a multi-stage screening process, including first and second screening, to select key sub-samples from all samples.

[0121] The database construction module calculates the optical constants of the base ink samples based on the data of the sub-samples and constructs a base ink database for color matching.

[0122] The sample optimization module includes:

[0123] The initial screening unit is configured to perform the first stage of sample screening based on the trend of spectral data as concentration changes, in order to determine the inflection point of reflectance change;

[0124] The fine screening unit is configured to perform a second-stage sample screening based on the linear relationship between sample concentration and color intensity function values, in order to select the most representative subsamples.

[0125] In summary, this invention ensures efficiency through the first screening, avoiding ineffective input in high-concentration areas, and ensures accuracy through the second screening, guaranteeing that the selected sample is the "optimal solution" for describing ink characteristics, thus improving overall efficiency. It eliminates the need for manually preparing and measuring dozens of highly subdivided base ink samples to obtain complete spectral data. In printing, for the desired target color, the required concentration of base ink can be deduced from the corresponding optical constants for mixing, and the error in color matching based on the base ink deduced from the optical constants can be reduced, improving accuracy.

[0126] Finally, it should be noted that the above descriptions are merely preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for matching a gradient-optimized spot color ink, characterized by, The method comprises the following steps: S1, preparing a plurality of base ink samples with different concentration gradients; S2, preparing color samples corresponding to the base ink samples; S3, measuring spectral data of each color sample by a spectral detection device; S4, performing first screening on the base ink samples based on the spectral data by analyzing the spectral variation rule to obtain initial sample points; S5, performing second screening based on the initial sample points by analyzing the linear relationship between color intensity and concentration to select two sub-sample points; S6, calculating optical constants of the base ink by using the two sub-sample points; S7, constructing a base ink database corresponding to the base ink according to the optical constants, which is used for special color ink color matching.

2. The gradient-optimized spot color ink matching method according to claim 1, characterized in that, The S1 comprises: S11, selecting base ink of a required color; S12, mixing the base ink with a diluent at different mass ratios to prepare base ink samples with different concentrations in a gradient manner; S13, recording sample numbers of the base ink samples with different concentrations.

3. The gradient-optimized spot color ink matching method according to claim 2, characterized in that, The S2 comprises: S21, stirring each base ink sample uniformly, and then using a color developing instrument to develop colors on the same printing material to prepare corresponding color samples; S22, according to the sample numbers of the base ink samples with different concentrations, corresponding sample numbers are given to the color samples.

4. The gradient-optimized spot color ink matching method according to claim 3, characterized in that, The S3 comprises: S31, obtaining the spectral reflectance R of each base ink sample color by the spectral detection device i ; S32, collecting spectral reflectivity of each base ink sample color sample; S33, obtaining the spectral reflectance R of the printing substrate by the spectral detection device P .

5. The gradient-optimized spot color ink matching method according to claim 4, characterized in that, The S4 comprises: S41, extract the reflectance value R of each base ink sample color sample at the main absorption wavelength λ λ ; S42, calculating derivative values of discrete data points by using a forward difference method; S43, finding base ink sample colors with "turning points" of reflectivity variation trend; S44, performing first screening to obtain initial sample points.

6. The gradient-optimized spot color ink matching method according to claim 5, characterized in that, The S5 comprises: S51, extracting reflectivity values at main absorption wavelengths of each initial sample point and corresponding concentrations of each initial sample point; S52, calculating a linear K / S value relationship between color intensity and concentration; S53, drawing a concentration-K / S value relationship graph, and performing linear fitting; S54, finding two initial sample points closest to the fitting straight line as sub-sample points.

7. The gradient-optimized spot color ink matching method according to claim 6, characterized in that: The S6 comprises: S61, constructing a matrix equation according to K / S values of the two sub-sample points; S62, calculating optical constants Z1 and Z2 of the base ink.

8. The gradient-optimized spot color ink matching method according to claim 7, characterized in that: In S7, the base ink database corresponding to the base ink sample can be constructed by using the optical constants Z1 and Z2. By selecting base ink samples of different colors and performing S1 to S6, the base ink database corresponding to the base ink sample can be constructed by using the optical constants.

9. A gradient-optimized spot color ink matching system for use in the gradient-optimized spot color ink matching method of any one of claims 1-9, characterized in that, The method comprises: a sample preparation module configured to prepare a plurality of base ink samples with different concentration gradients and prepare corresponding color samples; a spectral measurement module configured to measure spectral data of each base ink sample color sample; a sample optimization module configured to perform multi-stage screening including first screening and second screening based on the spectral data to select key sub-sample points from all sample points; a database construction module configured to calculate optical constants of the base ink sample according to data of the sub-sample points, and construct a base ink database for color matching.

10. A gradient-optimized spot color ink matching system, characterized by, The sample optimization module comprises: a first screening unit configured to perform first-stage sample screening according to a trend of spectral data changing with concentration to determine turning points of reflectivity variation; a second screening unit configured to perform second-stage sample screening according to a linear relationship between sample concentration and color intensity function value to select the most representative sub-sample points.

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