Fabric metamerism evaluation method resistant to chromatic aberration interference

Abstract

The present application belongs to the field of color science and textile printing and dyeing technology, and relates to a fabric metamerism evaluation method with anti-color difference interference. First, the reflectance spectrum curves of a standard color sample and batch color samples are obtained, denoted as and, and the standardization pretreatment is performed to obtain the standardized reflectance spectrum curves. Then, the spectral slope angles at each wavelength point are calculated. Based on the spectral slope angles at each wavelength point, the metamerism index M Y is calculated, and the metamerism degree is determined according to the value of M Y . The method is simple and easy to implement, has strong anti-color difference interference, and has obviously improved determination accuracy compared with the conventional special metamerism index M t evaluation method.

Description

Technical Field

[0001] This invention belongs to the field of color science and textile printing and dyeing technology, and relates to a method for evaluating metamerism of fabrics that resists color difference interference. Background Technology

[0002] Color is crucial in textiles, printing, packaging, and leather industries, and the accuracy of color reproduction directly impacts product quality and market performance. However, in actual production, metamerism can cause products to match colors under specific light sources, but the colors may no longer match when lighting conditions change. In the color matching process of textiles such as polyester, due to the difficulty in obtaining standard samples and original formulas, or limitations imposed by raw material supply, cost control, and environmental regulations, dye substitution is often necessary. This can lead to metamerism in different batches of products. The resulting substandard products will cause economic losses for manufacturers and pose a challenge to production enterprises.

[0003] Currently, for methods of evaluating metamerism in fabrics, the International Commission on Illumination (CIE) recommends the Special Metamerism Index (M... t The evaluation method (see GB / T 7771-2008 "Determination of Special Metamerism Index by Changing Illuminating Bodies") assesses the degree of metamerism by calculating the color difference change of the color sample under different light sources. However, this method depends on the test light source, and its evaluation results are affected by the color difference of the color sample under the reference light source. Specifically, when the batch color sample and the standard color sample are not completely identical in color under the reference light source (such as D65) (i.e., there is a slight color difference, such as a lightness difference ΔL)... * Chroma difference ΔC * When the hue angle difference (Δh) is small, this index is prone to misjudgment. Furthermore, in actual production, factors such as fabric colorant formulation, fabric batches, and process fluctuations make accurate color matching between two fabric samples under a reference light source difficult, necessitating correction of the tristimulus values. Existing correction methods are only effective within a small range of color difference under a reference light source and cannot effectively resist color difference interference generated during fabric production, leading to reduced accuracy in metamerism evaluation results.

[0004] Subsequent researchers proposed a series of general metamerism indices independent of the light source. For example, Reference 1 (Spectral fuzzy matching evaluation of metamerism degree[J]. Journal of Donghua University (Natural Science Edition). 2006, 32(1): 73-75) proposed an evaluation method based on the difference in spectral visual response, based on the Yang-Helmholtz opposition theory. Reference 2 (Study onmetamerism degree evaluation based on wavelength sensitive cone weighting algorithm[J]. Color Research and Application. 2019; 44(6): 894-909) constructed a wavelength sensitive cone weighting algorithm model based on long-wave, medium-wave, and short-wave cones (LMS), which showed good visual consistency in simulation experiments.

[0005] However, most existing methods are based on limited samples or simulated data, and their resistance to color difference interference under light sources has not been verified. On the other hand, if the color difference of the color sample is to be controlled within a small range before metamerism determination, a large number of dyeing experiments are required, which is time-consuming and labor-intensive, and difficult to meet the needs of rapid and efficient quality control in industrial production.

[0006] Therefore, it is of great significance to study a metamerism evaluation method for fabrics that is strong against color difference interference, accurate in judgment, and simple, in order to solve the problems existing in the current technology. Summary of the Invention

[0007] The purpose of this invention is to solve the problems existing in the prior art and provide a metamerism evaluation method for fabrics that resists color difference interference.

[0008] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0009] A method for evaluating metamerism of fabrics resistant to color difference interference, comprising the following steps:

[0010] (1) Under the same measurement conditions, the reflectance spectral curves of the standard color sample and the batch color sample were obtained respectively, and denoted as and , where λ represents the wavelength;

[0011] (2) To Standardization preprocessing was performed to obtain the standardized reflectance spectrum curve. To eliminate differences in overall reflectance intensity caused by sample thickness, dye concentration, or minor measurement deviations;

[0012] (3) Control the interval between any two adjacent wavelength points to be equal and not exceed 10 nm (preferably 10 nm), and calculate respectively. and At each wavelength point λ i The spectral slope angle at that point is denoted as θ1(λ). i ) and θ2(λ i );

[0013] (4) Based on θ1(λ) i ) and θ2(λ i The metamerism index M was calculated. Y M Y The calculation formula is:

[0014] ;

[0015] Wherein, the summation Σ is applied to all wavelength points λ involved in the slope calculation. i The formula is as follows: n represents the total number of wavelength points actually involved in the slope calculation; the divisor 180 in the formula represents the maximum difference (in degrees) between the slope angles of the two reflectance spectral curves at a single wavelength point, used to normalize the angle difference; 30 represents the total number of wavelength points involved in the slope calculation under the standard reference sampling interval (corresponding to 400~690 nm, 10 nm wavelength interval); 30 / n represents the sampling point number normalization factor, used to normalize the calculation results under different sampling intervals to the same level.

[0016] (5) M Y The value is compared with the preset judgment threshold T to determine whether there is metamerism between the standard color sample and the batch color sample;

[0017] If M Y If the value is ≥T, then it is determined that there is metamerism between the standard color sample and the batch color sample.

[0018] If M Y If <T, it is determined that there is no metamerism between the standard color sample and the batch color sample.

[0019] As a preferred technical solution:

[0020] As described above, the method for evaluating metamerism of fabrics to resist color difference interference has the following measurement conditions in step (1): wavelength range of 400~700 nm (i.e., visible light band). Since the human eye has low visual sensitivity to edge bands below 400 nm and above 700 nm, this region has little impact on the calculation results, so only the 400~700 nm band is selected, with a wavelength interval of 10 nm.

[0021] As described above, in the metamerism evaluation method for fabrics that resist color difference interference, the vertical axis of the reflectance spectral curve in step (1) is the percentage value of reflectance, which ranges from 0 to 100.

[0022] As described above, in the metamerism evaluation method for fabrics resisting color difference interference, the standardization preprocessing in step (2) adopts the scaling method, which is specifically implemented through the following formula:

[0023] ;

[0024] Among them, the summation Σ is performed for all measurement wavelengths.

[0025] As described above, in the metamerism evaluation method for fabrics resisting color difference interference, θ1(λ) in step (3) i ) and θ2(λ i The calculation formulas for ) are as follows:

[0026] ;

[0027] ;

[0028] Where R1(λ) i ) and R1(λ i+1 ) are respectively At wavelength λ i and the next sampling wavelength λ i+1 Spectral reflectance at that location and They are respectively At wavelength λ i and the next sampling wavelength λ i+1 The spectral reflectance at a given location, where Δλ is the sampling wavelength interval.

[0029] As described above, in the method for evaluating metamerism of fabrics to resist color difference interference, the value of the threshold T in step (5) is related to the wavelength range and sampling wavelength interval used during measurement.

[0030] As described above, in a method for evaluating metamerism of fabrics to resist color difference interference, when the measurement wavelength range is 400~700 nm and the sampling wavelength interval Δλ is 10 nm, the judgment threshold T is 0.5.

[0031] Invention principle:

[0032] Existing metamerism indices are mostly based on the weighted absolute value accumulation or weighted square accumulation of the amplitude difference of reflectance spectral curves. Under a reference light source, if there are overall spectral amplitude differences due to measurement conditions or concentration variations, the accumulated value will be large, leading to misjudgments. Furthermore, existing metamerism indices in the literature typically only select a limited number of experimental samples for verification. These samples do not cover the different color characteristics that may occur in actual fabric production, making it difficult to adapt to the diverse color situations of fabrics in actual production, and thus they have not been widely used. In contrast, this invention, in the experimental design stage, fully considers the actual scenarios in fabric production, systematically constructing dyed fabric samples covering different brightness, chroma, hue angles, and shades. The selected samples are comprehensive and representative. Secondly, to verify its resistance to color difference interference, samples with increasing color difference gradients are prepared to simulate color deviations that may occur under a reference light source in actual production.

[0033] Metamerism is essentially due to the different shapes of the reflectance spectral curves of two samples within the visible light band. The slope angle proposed in this invention... Calculations based on reflectance variations in adjacent bands directly reflect the consistency of the local variation directions of the two curves across the entire spectral range. As long as the variation trends of the two spectral curves are consistent across all bands, then θ1(λ) i ) and θ2(λ i ) are close in most bands, thus M Y Smaller; when there are large differences in spectral shape (e.g., some bands rise while others fall, peaks and troughs are different, etc.), then θ1(λ) i ) and θ2(λ i The value increases across multiple bands and accumulates across the entire band, thus M Y Increase.

[0034] On the other hand, even if the two spectral curves have physical differences in a certain wavelength band due to residual chromatic aberration (i.e., However, as long as their changing trends (slopes of adjacent bands) are consistent, the calculated results will be... This will keep the value relatively small, thus effectively avoiding interference from residual chromatic aberration of the reference light source.

[0035] Beneficial effects:

[0036] (1) The metamerism evaluation method for fabrics with resistance to color difference interference of the present invention eliminates the overall reflection intensity difference through standardized preprocessing, and constructs an evaluation index based on the slope angle of the color sample reflectance spectrum curve. It has strong anti-interference ability, accurate evaluation, stability, and can accurately judge metamerism when the color difference between the standard color sample and the batch color sample is large.

[0037] (2) The metamerism evaluation method for fabrics with resistance to color difference interference of the present invention is simple to operate and does not require a test light source or repeated dyeing experiments (in order to control the color difference between color samples within a small visual color difference range). It only requires measuring the reflectance spectral curves of standard color samples and batch color samples, and the judgment can be completed by formula calculation. It can also be integrated into an automated quality control system. It is applicable to color quality control in textile dyeing and finishing, plastic coloring, ink printing and other fields, which helps to reduce production misjudgment, improve product color consistency, increase production efficiency and reduce production costs. Attached Figure Description

[0038] Figure 1 This is a flowchart of the metamerism evaluation method for fabrics resisting color difference interference according to the present invention;

[0039] Figure 2 This is a schematic diagram of the reflectance spectrum curves of a group of near-identical color samples with increasing brightness in Example 1;

[0040] Figure 3 The method of Embodiment 1 of the present invention (M) Y ) and the special metamerism index method (M t ) with lightness difference (ΔL) * A comparative diagram showing the changes;

[0041] Figure 4 This is a schematic diagram of the reflectance spectral curves of a group of near metamerism samples with increasing chroma in Embodiment 4 of the present invention;

[0042] Figure 5 The method of embodiment 4 of the present invention (M) Y ) and the special metamerism index method (M t ) with chroma difference (ΔC) * A comparative diagram showing the changes. Detailed Implementation

[0043] The present invention will be further described below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Furthermore, it should be understood that after reading the teachings of this invention, those skilled in the art can make various alterations or modifications to the invention, and these equivalent forms also fall within the scope defined by the appended claims.

[0044] Example 1

[0045] A method for evaluating metamerism in fabrics that resists color difference interference, the specific steps of which are as follows:

[0046] (1) Dye solution formula;

[0047] dye;

[0048] High-temperature dispersing leveling agent Sinlever K-541 (Kunshan Mingjia Auxiliary Agents Co., Ltd.) 1.5 g / L;

[0049] (2) Dyeing process flow:

[0050] Place the fabric into the dye cup → add dye liquor → place the dye cup into the dyeing machine (initial temperature is 25 ℃) → heat up to 90 ℃ at 2 ℃ / min → heat up to 130 ℃ at 1 ℃ / min → keep warm for 30 min → cool down to 60 ℃ at 2 ℃ / min → wash with water at room temperature → air dry naturally;

[0051] The fabric used was a plain white polyester woven fabric (area density 137 g / m²). 2 The warp and weft density is 139×79 threads / inch, 135D×150D (provided by Shanghai Binyou New Material Technology Co., Ltd.); the dyes used are Zenix Yellow AC-E (abbreviated as YA), Zenix Red AC-E (abbreviated as RA), and Zenix Blue AC-E (abbreviated as BA); all dyes used are industrial grade and provided by Zhejiang Zhengyu Chemical Co., Ltd.; the pH of the dye bath is 4.5~5.5; the dyeing bath ratio is 1:40.

[0052] (3) Sample preparation;

[0053] Using yellow, red, and blue primary color dyes, the dyeing formula shown in Table 1 was obtained through adjustments. Following the above dye solution formula and process flow, seven color samples with increasing lightness gradients (chroma and hue angle remaining constant) under a D65 light source were prepared and sequentially labeled SL0 (as standard sample), SL1~SL6 (as batch samples). The reflectance spectral curves of this group of color samples maintained a high degree of consistency, with the curves almost completely overlapping (e.g., ...). Figure 2 As shown in the figure, these color samples were visually evaluated by senior color assessment engineers using multiple light sources (D65, TL84, A) and were determined to be near-identical color samples.

[0054] Table 1. Dyeing formulas for near-identical colors with increasing brightness.

[0055] (4) such as Figure 1 As shown, under the same measurement conditions, the reflectance spectral curves of the standard color sample and the batch color sample were obtained using a spectrophotometer, denoted as . and , where λ represents the wavelength; the measurement conditions are: wavelength range 400~700 nm, wavelength interval 10 nm;

[0056] The vertical axis of the reflectance spectrum curve represents the percentage value of reflectance, ranging from 0 to 100.

[0057] (5) First, calculate the reflectance spectrum curves of the standard color samples respectively. Reflectance spectrum curves of batch color samples The sum of reflectance at all wavelengths is used to scale the values. Standardization preprocessing was performed to obtain the standardized reflectance spectrum curve. Specifically, this is achieved through the following formula:

[0058] ;

[0059] Among them, the summation Σ is performed over all measurement wavelengths;

[0060] (6) Ensure that the interval between any two adjacent wavelength points is equal, and calculate the intervals respectively. and At each wavelength point λ i The spectral slope angle at (400~690 nm) is denoted as θ1(λ). i ) and θ2(λ i );

[0061] θ1(λ i ) and θ2(λ i The calculation formulas for ) are as follows:

[0062] ;

[0063] ;

[0064] Where R1(λ) i ) and R1(λ i+1 ) are respectively At wavelength λ i and the next sampling wavelength λ i+1 Spectral reflectance at that location and They are respectively At wavelength λ i and the next sampling wavelength λ i+1 The spectral reflectance at a given location, where Δλ is the sampling wavelength interval;

[0065] (7) Based on θ1(λ) i ) and θ2(λ i The metamerism index M was calculated. Y M Y The calculation formula is:

[0066] ;

[0067] Wherein, the summation Σ is applied to all wavelength points λ involved in the slope calculation. i Proceed; at this point, n=30;

[0068] (8) M Y The value is compared with the preset judgment threshold T to determine whether there is metamerism between the standard color sample and the batch color sample; the value of the judgment threshold T is related to the wavelength range and sampling wavelength interval used during measurement, and the judgment threshold T is 0.5;

[0069] If M Y If the value is ≥T, then it is determined that there is metamerism between the standard color sample and the batch color sample.

[0070] If M Y If <T, it is determined that there is no metamerism between the standard color sample and the batch color sample.

[0071] According to the national standard GB / T 7771-2008 "Determination of Specific Metamerism Index by Changing the Illuminating Source", using D65 as the reference light source and A light source as the test light source, the specific metamerism index M of the same sample pairs (SL0 and SL1~SL6) in the examples was calculated. t Among them, ΔE 00 The color difference between the standard color sample and the batch color sample under a D65 light source is calculated using the CIE DE2000 color difference formula.

[0072] Table 2 Test results of near-identical color samples with increasing lightness.

[0073] (Note: In visual judgment, "present" indicates the presence of metamerism, and "absent" indicates the absence of metamerism.)

[0074] As shown in Table 2, in ΔL * From 0.96 to 3.59, the traditional M t With the present invention M Y The judgment results were all consistent with the visual assessment. However, by Figure 3 It can be seen that, with ΔL * The increase of M t It increases linearly (K=0.1044), while M... Y The change is relatively gradual (K=0.0264). This illustrates the M proposed in this invention. Y When subjected to brightness difference interference, it has better performance than traditional M t It offers superior stability, eliminating numerical fluctuations caused by brightness mismatches in color samples under reference light sources, and providing stronger anti-interference capabilities.

[0075] Example 2

[0076] A method for evaluating metamerism of fabrics that resists color difference interference, the basic steps are the same as in Example 1, the only difference is in step (3) sample preparation;

[0077] Using yellow, red, and blue primary color dyes, the dyeing formula shown in Table 3 was obtained through adjustments. Following the aforementioned dye solution formula and process flow, seven color samples with increasing chroma gradients under a D65 light source were prepared and labeled SC0 (as standard sample) and SC1~SC6 (as batch color samples). The reflectance spectral curves of this group of color samples showed a high degree of consistency, with the curves almost completely overlapping. Furthermore, both groups of color samples were visually assessed as near-identical color samples under different light sources (D65, TL84, A) and determined to be of similar color spectrum.

[0078] Table 3. Dyeing formulas for near-identical colors and spectra with increasing chroma.

[0079]

[0080] Table 4 Test results of near-identical color samples with increasing chroma.

[0081] (Note: In visual judgment, "present" indicates the presence of metamerism, and "absent" indicates the absence of metamerism.)

[0082] Example 3

[0083] A method for evaluating metamerism of fabrics that resists color difference interference, the basic steps are the same as in Example 2, the only difference is in step (3) sample preparation;

[0084] Using yellow, red, and blue primary dyes, the dyeing formula shown in Table 5 was obtained through adjustments. Following the aforementioned dye solution formula and process flow, seven color samples with increasing hue angle gradients under a D65 light source were prepared and sequentially labeled Sh0 (as standard sample) and Sh1~Sh6 (as batch samples). The reflectance spectral curves of this group of color samples showed a high degree of consistency, with the curves almost completely overlapping. Furthermore, both groups of color samples were visually assessed as near-identical color samples under different light sources (D65, TL84, A) and determined to be of similar hue and spectrum.

[0085] Table 5. Dyeing formulas for near-identical colors and spectra with increasing hue angles.

[0086]

[0087] Table 6 Test Results of Nearly Identical Color Samples with Increasing Hue Angle

[0088]

[0089] (Note: In visual judgment, "present" indicates the presence of metamerism, and "absent" indicates the absence of metamerism.)

[0090] As shown in Tables 4 and 6, when the chroma difference or hue angle difference between color samples is small, the traditional method (M) t ) and the method of the present invention (M) YAll of them can make the correct judgment. However, when ΔC * When M ≥ 1.75 (Δh ≥ 12.84), t If the threshold of 0.5 is exceeded, the color sample is incorrectly identified as exhibiting metamerism, resulting in a misjudgment. This indicates that M... t Metamerism in fabrics can only be correctly judged when the color difference between the color samples is extremely small (close to perfect matching). In actual production, it is easily affected by color difference and misjudgment may occur.

[0091] In contrast, the M proposed in this invention Y Within a range where the chroma difference increases from 0.43 to 4.11 (and the hue angle difference increases from 2.26 to 19.17), the accuracy remains stable, far below the judgment threshold of 0.5, and all judgment results are consistent with the visual evaluation, with a false judgment rate of 0. This demonstrates that the method of the present invention can effectively resist interference caused by chroma and hue angle differences, and its accuracy is significantly higher than that of traditional methods, solving the defect of traditional methods that are prone to false judgments when the color difference of the color sample is not perfectly matched.

[0092] Example 4

[0093] A method for evaluating metamerism of fabrics that resists color difference interference, the basic steps are the same as in Example 2, the only difference is in step (3) sample preparation;

[0094] Using the near-identical color samples SC1~SC6 from Example 2 as standard color samples, the YA, RA, BA dye combination was replaced with the YA, RA, BG dye combination, where BG is the abbreviation for Zenix Blue S-BG dye. The dyeing formulas shown in Table 7 were obtained using a computer color matching system, and color samples (ΔE) matching the color of each standard color sample under a D65 light source were prepared. 00 ≤0.5), labeled SC1-1 to SC6-1. Using SC0 as the standard sample, it is combined with SC1-1 to SC6-1 respectively to form the chroma C. * Increasingly similar metamerism samples. For example... Figure 4 As shown, the reflectance spectral curves of these newly dyed color samples are significantly different from those of the standard sample SC0, and they exhibit obvious visual differences under light source A. After visual evaluation, they were all determined to be near metamerism color samples.

[0095] Table 7. Dyeing Formulas for Metamerism Samples with Increasing Chroma

[0096]

[0097] Table 8 Test results of near metamerism samples with increasing chroma

[0098]

[0099] (Note: In visual judgment, "present" indicates the presence of metamerism, and "absent" indicates the absence of metamerism.)

[0100] As shown in Table 8, for near metamerism samples, M t With M Y Both can correctly identify metamerism in color samples. However, due to... Figure 5 It can be seen that, with ΔC * In the changes, M t The growth rate (K=0.2086) is greater than that of M. Y (K=0.1305). This indicates that even under the premise of correct determination, the present invention M... Y It is less affected by fluctuations in color difference parameters under a reference light source, resulting in more stable evaluation results.

[0101] Experiments show that for near-identical spectral samples with highly consistent spectral shapes but exhibiting color differences under a reference light source, as ΔL... * / ΔC * / Δh increases, traditional M t It exhibits linear growth (K=0.1044), and when ΔL * / ΔC * When / Δh exceeds a certain value, M t There is a possibility of misjudgment; however, the M proposed in this invention... Y It remained consistently stable (K=0.0264), with extremely low and gradual values ​​(fluctuating between 0 and 0.1), and a false positive rate of 0. For near-metachromatic samples, both indices were correctly identified, but M... Y With ΔL * / ΔC * It exhibits stronger stability (K=0.1305) in the change of / Δh and is less affected by parameter disturbances.

[0102] Example 5

[0103] A method for evaluating metamerism of fabrics to resist color difference interference, the basic steps are the same as in Example 2, the difference being in step (1) dye solution formulation, step (2) dyeing process flow and step (3) sample preparation, as follows:

[0104] (1) Dye solution formula;

[0105] dye;

[0106] High-temperature dispersing leveling agent Sinlever K-541 (Kunshan Mingjia Auxiliary Agents Co., Ltd.) 1.5 g / L;

[0107] (2) Dyeing process flow:

[0108] Place the fabric into the dye cup → add dye solution → place the dye cup into the dyeing machine (initial temperature 40 °C) → heat up to 80 °C at 2 °C / min → heat up to 90 °C at 0.5 °C / min → heat up to 130 °C at 1 °C / min → keep warm for 40 min → cool down to 50 °C at 2 °C / min → wash with water at room temperature → air dry naturally;

[0109] The fabric used was a plain white polyester woven fabric (area density 137 g / m²). 2 The fabric has a warp and weft density of 139*79 threads / inch and a diameter of 135D*150D, provided by Shanghai Binyou New Material Technology Co., Ltd. The dyes used are Disperse Yellow E-3GL 200% (E-3GL), Disperse Yellow SE-5GF (SE-5GF), Disperse Yellow S-6G (S-6G), Disperse Yellow E-5G (E-5G), Disperse Violet HFRL (HFRL), Disperse Red E-BF 200% (E-BF), Disperse Red WLS-B (WLS-B), Disperse Red SE-3GL (SE-3GL), Disperse Blue S-RF (S-RF), Disperse Blue S-TG (S-TG), Disperse Blue PD-RD (PD-RD), and Disperse Blue CRE (CRE). All dyes used are industrial grade and provided by Fino Dyestuff Chemical Co., Ltd. The dye bath pH is 4.5~5.5; the dyeing bath ratio is 1:40.

[0110] (3) Sample preparation;

[0111] A gray sample was selected as the standard color sample (S-6G:HFRL:S-TG). The aforementioned yellow, red, and blue primary color dyes were selected, and computer color matching software was used to generate the dyeing formulas shown in Table 9. During color matching, one dye from each of the three primary colors was randomly selected and combined to generate 64 batches of different dye combinations, numbered 1 to 64. The dyeing factory's color assessment engineer determined the metamerism of the color samples under D65 and A light source conditions. These color samples included 5 pairs of color samples that did not exhibit metamerism (nearly identical color and same spectrum, corresponding to numbers 2, 3, 19, 20, and 21) and 59 pairs of color samples that exhibited metamerism (nearly identical color and same spectrum).

[0112] Table 9 Dyeing formulations for different dye combinations

[0113]

[0114]

[0115] Table 10 M under different dye combinations t With M Y Accuracy of judgment

[0116]

[0117] As shown in Table 10, M Y The overall accuracy rate was 98.4%. For samples with nearly identical color and spectrum, the accuracy rate was 100%, and for samples with nearly identical color and metamerism, the accuracy rate was 98.3%. This indicates that even if there are differences in the chemical structure of the dyes, M... Y It can still accurately determine metamerism in fabrics and has good applicability to changes in dye structure. In contrast, M t The accuracy rate of judgment was 92.2%, and all samples with similar colors and spectra were misjudged, indicating that M... t It is greatly affected by the structure of the dye.

[0118] Example 6

[0119] A method for evaluating metamerism of fabrics that resists color difference interference, the basic steps are the same as in Example 5, the only difference is in step (3) sample preparation;

[0120] Using a plain polyester fabric (P-1) as a base, a gray sample was selected as the standard color sample (S-6G: HFRL:S-TG). By adjusting the dye combination and dyeing formula (as shown in Table 11), batch color samples with different degrees of metamerism compared to the standard color sample were prepared. The above standard color sample and batch color sample formulas were then applied to the dyeing of polyester fabrics of different specifications (Table 12).

[0121] Table 11 Dyeing Formulas for Different Sizes of Color Samples

[0122] Table 12 Fabric Specifications

[0123] (Note: Pile fabrics contain individual pile yarns, and the pile yarn specifications must be listed separately. The third data point is the fineness of the pile yarn.)

[0124] Table 13 M after dyeing of fabrics of different specifications t Changes in value

[0125]

[0126] Table 14 M after dyeing of fabrics of different specifications Y Changes in value

[0127]

[0128] As shown in Table 13, for color samples that are visually judged not to produce metamerism, the M values ​​for all samples are... t The values ​​all exceeded the judgment threshold of 0.5, M tThe judgment results do not match the visual evaluation results. Furthermore, for different fabric specifications, the maximum standard deviation of the color samples was 1.31, and the maximum coefficient of variation was 31.53%, indicating that changes in fabric specifications affect M. t The specific value of M has a significant impact. t The stability of the determination across different fabric specifications is poor.

[0129] In contrast, as shown in Table 14, M Y The judgment result is the same as the visual evaluation result, and the sample M of different sizes is the same. Y The maximum standard deviation of the value is 0.18, indicating that the variation in fabric specifications only affects M. Y The specific value of M has a negligible impact. Y Its performance evaluation is not easily affected by parameters such as fabric density and structure, and it has good applicability to changes in fabric specifications.

Claims

1. A method for evaluating metamerism of fabrics resistant to color difference interference, characterized in that... Includes the following steps: (1) Under the same measurement conditions, the reflectance spectral curves of the standard color sample and the batch color sample were obtained respectively, and denoted as and , where λ represents the wavelength; (2) To Standardization preprocessing was performed to obtain the standardized reflectance spectrum curve. ; The standardization preprocessing uses a scaling method, specifically implemented using the following formula: ； Among them, the summation Σ is performed over all measurement wavelengths; (3) Ensure that the interval between any two adjacent wavelength points is equal and does not exceed 10 nm, and calculate the results respectively. and At each wavelength point λ i The spectral slope angle at that point is denoted as θ1(λ). i ) and θ2(λ i ); θ1(λ i ) and θ2(λ i The calculation formulas for ) are as follows: ； ； Where R1(λ) i ) and R1(λ i+1 ) are respectively At wavelength λ i and the next sampling wavelength λ i+1 Spectral reflectance at that location and They are respectively At wavelength λ i and the next sampling wavelength λ i+1 The spectral reflectance at a given location, where Δλ is the sampling wavelength interval; (4) Based on θ1(λ) i ) and θ2(λ i The metamerism index M was calculated. Y M Y The calculation formula is: ； Wherein, the summation Σ is applied to all wavelength points λ involved in the slope calculation. i Perform; n is the total number of wavelength points actually involved in the slope calculation; (5) M Y The value is compared with the preset judgment threshold T to determine whether there is metamerism between the standard color sample and the batch color sample; If M Y If the value is ≥T, then it is determined that there is metamerism between the standard color sample and the batch color sample. If M Y If <T, it is determined that there is no metamerism between the standard color sample and the batch color sample.

2. The method for evaluating metamerism of fabrics to resist color difference interference according to claim 1, characterized in that, The measurement conditions in step (1) are: wavelength range of 400~700 nm, wavelength interval of 10 nm.

3. The method for evaluating metamerism of fabrics to resist color difference interference according to claim 2, characterized in that, In step (1), the vertical axis of the reflectance spectrum curve represents the percentage value of reflectance, ranging from 0 to 100.

4. The method for evaluating metamerism of fabrics to resist color difference interference according to claim 3, characterized in that, In step (5), the value of the threshold T is related to the wavelength range and sampling wavelength interval used during measurement.

5. The method for evaluating metamerism of fabrics to resist color difference interference according to claim 4, characterized in that, When the measurement wavelength range is 400~700 nm and the sampling wavelength interval Δλ is 10 nm, the judgment threshold T is 0.5.

Images