Color difference control method based on visual perception and application thereof

Abstract

The invention provides a color difference control method based on visual perception and application thereof, and relates to the technical field of color difference control. According to the chromatic aberration control method, the L * a * b * value of the sample without visual chromatic aberration is obtained based on human visual perception, so that a visual threshold range is established, the fluctuation range of L *, a * and b * of the sample without visual chromatic aberration can also be obtained, the L * a * b * value in the range has no visual chromatic aberration with a standard sample, and therefore, the chromatic aberration control method has the advantages that the visual threshold range is established; during production, the difference value between the L * a * b * value of the batch sample and the L * a * b * value of the standard sample is controlled within the fluctuation range, the obtained batch sample and the standard sample have no visual chromatic aberration, a formula or process does not need to be finely adjusted when batch pigment samples are used, the production efficiency is improved, and the method is suitable for controlling the chromatic aberration of pigments, coatings, printing ink, printed and dyed products, plastic products, papermaking, rubber products or ceramics.

Description

Technical Field

[0001] The present invention relates to the technical field of color difference control, and particularly relates to a color difference control method based on visual perception and its application. Background Art

[0002] In modern production processes, the accurate reproduction of color is one of the key factors to ensure product quality and consumer satisfaction. However, due to differences in the nature of pigments themselves, instability in production processes, and changes in environmental factors, color differences are likely to occur during the production and use of pigments. In many industries such as pigments, coatings, inks, printing and dyeing, plastic products, paper making, rubber products, and ceramics, color difference control is a crucial technology.

[0003] However, traditional color difference control methods use pigments with stable quality as standard samples, mainly relying on the experience of technicians to agree on a maximum color difference, and during production, the formula is fine-tuned based on past experience to ensure that the color difference between batch samples and standard samples is less than the maximum color difference. To improve the adjustment speed, a color difference meter is often used to measure the color difference and phase deviation of colors. Although the color difference meter can provide accurate data, it often cannot fully reflect the human eye's perception of color, sometimes resulting in a large difference between the measured color difference and the visual color difference, that is, the measured color difference is within the range, but the color difference perceived by the human eye is very obvious. And the main way for consumers to distinguish color differences is still the visual color difference based on human eye vision, which makes it difficult for traditional color difference control methods to meet the color difference requirements of human eye vision. Summary of the Invention

[0004] The present invention aims to at least solve one of the above technical problems existing in the prior art. For this reason, the purpose of the present invention is to provide a color difference control method, which obtains a large amount of color difference data based on human eye visual perception, and obtains the range of L values of the visually acceptable color difference range, combines instrument measurement with visual perception, and controls the L values of the colors of batch samples, so as to achieve the purpose of color difference control. * a * b * value range, combines instrument measurement with visual perception, and controls the L values of the colors of batch samples. * a * b * value to achieve the purpose of color difference control.

[0005] The second aspect of the present invention lies in providing an application of a color difference control method.

[0006] To achieve the above purpose, the technical solutions adopted by the present invention are as follows:

[0007] The first aspect of the present invention provides a color difference control method, including the following steps:

[0008] S1. Measure the L*a*b* values of the standard sample and record them on the L*a*, a*b*, and L*b* planes in the CIELAB color space; using these as the center points, adjust the L*, a*, and b* values on the L*a*, a*b*, and L*b* planes around the center points to obtain different L*a* values, a*b* values, and L*b* values, and prepare 70 - 100 test samples according to the L*a* values, a*b* values, and L*b* values obtained above;

[0009] S2. Have several persons with normal vision screen the test samples to obtain 36 - 60 samples that are visually colorless from the standard sample and are evenly distributed around the center point, and record the L*a*b* values of the obtained samples;

[0010] S3. Fit the L*a*b* data collected in step S2 by a computer to form a 3D ellipsoid graph, obtain the visual threshold range and the maximum values by which L * , a * , b * can deviate; control the L*a*b* values of the batch samples within the visual threshold range, then the samples with the L*a*b* values are visually colorless from the standard sample in step S1; the fitting equation is as follows:

[0011]

[0012] where, (x 0 , y 0 , z 0 ) are the L*a*b* values of the standard sample, (x, y, z) are the L*a*b* values of the test sample, and a, b, c respectively represent the semi - axis lengths of the ellipsoid.

[0013] The color difference control method of the present invention takes the L*a*b* values of the samples that are visually colorless based on visual perception as data collection points, and obtains a three - dimensional ellipsoid, i.e., the visual threshold range, through computer fitting. This visual threshold range is the fluctuation range of the samples that are visually colorless based on visual perception Therefore, the L*a*b* values during production can be controlled through these data fluctuation ranges, so as to obtain the batch colors that are visually colorless to the human eye. When technicians use batch pigment samples, they do not need to fine - tune the formula or process due to visual color difference problems, which can not only improve production efficiency, but also improve the quality of products and product competitiveness.

[0014] In the fitting equation of step S3, a, b, c also represent the maximum values by which L * , a * , b * can deviate

[0015] In the selection of the standard sample, generally, the first batch of samples produced from raw materials and pigments with stable quality are used as the standard sample, or the demander provides corresponding color samples as the standard sample.

[0016] In some embodiments of the present invention, in the step S1, the differences between the obtained different L*, a*, and b* values after adjustment and the L*, a*, and b* values of the standard sample are ≤1.

[0017] In some embodiments of the present invention, in the step S1, the angles between the straight lines where the obtained L*a*, a*b*, and L*b* values are located on the L*a*, a*b*, and L*b* planes and the horizontal or vertical axes of the plane are 10 - 30°.

[0018] In some embodiments of the present invention, the number of visually normal persons in the step S2 is 6 - 8.

[0019] In some embodiments of the present invention, in the step S2, the screening is carried out under a light source with an illuminance of 1030 - 1040 lx and a color temperature of 6740 - 6750 K.

[0020] In some embodiments of the present invention, in the step S2, before the screening, the visually normal persons first perform visual adaptation on the background color within the same visual range as the test sample during the screening; the adaptation time is ≥1 min.

[0021] In some embodiments of the present invention, in the step S2, the observation time of each test sample by the visually normal persons during the screening is 2 - 3 s.

[0022] Control the observation time to make the experiment simple, easy to operate, and reduce the memory of the observer about the previous judgment.

[0023] In some embodiments of the present invention, during the screening in the step S2, after the visually normal persons observe 30 - 40 test samples, they rest for 10 - 20 min. This can avoid visual fatigue caused by long - time observation, as well as habitual errors, expectancy errors, practice errors, and fatigue errors in the visual judgment of the same color central color sample.

[0024] In some embodiments of the present invention, in the step S2, during the screening, the distance between the visually normal persons and the test sample is 45 - 55 cm.

[0025] The second aspect of the present invention provides an application of the color difference control method described in the first aspect of the present invention in controlling the color difference of pigments, coatings, inks, printed and dyed products, plastic products, papermaking, rubber products, or ceramics.

[0026] The color difference control method of the present invention is applicable to controlling the color difference of pigments, coatings, inks, printed and dyed products, plastic products, paper, rubber products or ceramics, and can be used in the production of colored products such as pigments and coatings, and the color difference is judged by using this color difference control method.

[0027] In some embodiments of the present invention, during the production process of the pigment, the color difference control method is used to judge whether there is a visual color difference, so that the product has no color difference in human eye visual perception.

[0028] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0029] The color difference control method of the present invention is based on human eye visual perception, obtains the L*a*b* value of a sample with no visual color difference, and thereby establishes a visual threshold range, that is, the fluctuation range of △L*, △a* and △b* of the sample with no visual color difference. The L*a*b* value within this range has no visual color difference from the standard sample. Therefore, during production, controlling the difference between the L*a*b* value of the batch sample and the L*a*b* value of the standard sample within this visual threshold range results in the batch sample having no visual color difference from the standard sample. When using the batch pigment sample, there is no need to fine-tune the formula or process again, improving production efficiency. The color difference control method based on visual perception of the present invention overcomes the problem in the prior art that only a color difference value is specified according to experience, resulting in the situation that in the production of some products, the calculated color difference is feasible, but the color difference seen by the human eye is obvious. It is applicable to controlling the color difference of pigments, coatings, inks, printed and dyed products, plastic products, paper, rubber products or ceramics. Description of the Drawings

[0030] Figure 1 It is the adjustment direction on the L*a*, a*b* and L*b* planes in step S1 of the embodiment of the present invention.

[0031] Figure 2 It is the visual threshold range obtained in step S3 of Embodiment 1 of the present invention.

[0032] Figure 3 It is the visual threshold range obtained in step S3 of Embodiment 2 of the present invention.

[0033] Figure 4 It is the visual threshold range obtained in step S3 of Embodiment 3 of the present invention. Detailed Embodiments

[0034] The content of the present invention will be further described in detail below through specific embodiments. The raw materials, reagents or devices used in the embodiments and comparative examples can be obtained from conventional commercial channels or can be obtained by existing technical methods without special instructions. Unless otherwise specified, the test or measurement methods are all conventional methods in the art.

[0035] In the following embodiments of the present invention, during the screening process in step S2, the light source in the Day mode of the Gretag Macbeth The JudgeⅡ multi-light source standard viewing booth is selected for observation (its illuminance is 1036 lx and the color temperature is 6748 K). The booth has a gray background. The standard sample and the color sample are placed in the central position and are blocked by a gray baffle (with a cut-out of 10 cm × 20 cm in the middle). At the same time, the standard sample (color center) is pasted on one side, and only the standard sample and the color sample are presented within the observer's line of sight each time; the viewing booth is preheated for 5 minutes.

[0036] The size of the sample is 10 cm × 10 cm. The observer observes at a distance of about 50 cm from the color sample pair and adapts to the background color for 1 minute before observation; the observer takes a 15-minute break after observing 30 - 40 color samples.

[0037] In the following embodiments, the points of the L*a*b* values of the standard sample on the planes of L*a*, a*b*, and L*b* are used as the center points and are adjusted along the Figure 1 direction shown (the included angle in the figure is 30°) to obtain different L*a* values, a*b* values, and L*b* values, and test samples are prepared according to these L*a* values, a*b* values, and L*b* values.

[0038] The fitting equation is: where, (x 0 , y 0 , z 0 ) are the L*a*b* values of the standard sample, (x, y, z) are the L*a*b* values of the test sample, and a, b, c respectively represent the semi-axis lengths of the ellipsoid.

[0039] The following is a detailed description in combination with specific embodiments.

[0040] Embodiment 1

[0041] A method for color difference control based on visual perception includes the following steps:

[0042] S1. Use a color difference meter to measure the L * a * b * values of the standard sample of blue pigment (Pigment Blue 15:2). L * = 80.07, a * = -11.88, b *= -19.81 and record it on the L*a*, a*b*, and L*b* planes in the CIELAB color space; adjust the L*a*b* values on the L*a*, a*b*, and L*b* planes respectively to obtain different L*, a*, and b* values, and prepare 90 test samples according to the L*, a*, and b* values; the differences between the adjusted different L*, a*, and b* values and the L*, a*, and b* values of the standard sample are ≤ 1;

[0043] S2. Screening of color sample colors: Select 6 observers with normal vision. Under the test condition of GretagMacbeth The JudgeⅡ multi-light source standard observation box Day mode, the observers screen the test samples at a distance of about 50 cm from the color samples, and each color is observed for 2 s. The observers are required to make a judgment on whether there is a color difference from the standard sample immediately, and obtain the samples with no visual color difference from the standard sample; take the maximum value of △L*, △a*, and △b* of the samples with no visual color difference as the collection point, and uniformly collect the L*a*b* values of 36 of the samples with no visual color difference around the center point;

[0044] S3. Data analysis of the product: Fit the data of the L * a * b * values obtained in step S2 on a computer to obtain the visual threshold range as shown Figure 2 shown.

[0045] From Figure 2 it can be obtained and

[0046] Verify the color difference control method of Example 1, combine the L * a * b * values of different batches of samples and the ΔL * , Δa * and Δb * with the standard sample, judge whether there is a color difference (test color difference) between the batch sample and the standard sample, and then let the human eye judge whether there is a color difference (visual color difference) between the batch sample and the standard sample under the same screening conditions as in step S2 above. The results are shown in Table 1 below.

[0047] Table 1 Results of visual color difference and test color difference of different batches in Example 1

[0048] Specimen <![CDATA[L * > <![CDATA[a * > <![CDATA[b * > <![CDATA[ΔL * > <![CDATA[Δa * > <![CDATA[Δb * > Measured color difference Visual color difference Batch sample 1 79.64 -12.13 -19.61 0.43 0.25 0.20 Qualified Qualified Batch sample 2 79.78 -12.20 -19.88 0.29 0.32 0.07 Unqualified Unqualified Batch sample 3 80.27 -11.68 -20.30 0.20 0.2 0.49 Unqualified Unqualified

[0049] Example 2

[0050] A method for controlling color difference based on visual perception, comprising the following steps:

[0051] S1. Use a color difference meter to measure the L*a*b* values of the standard sample (a coating containing Pigment Red 188), where L* = 81.21, a* = 23.84, and b* = 1.50, and record them on the L*a*, a*b*, and L*b* planes in the CIELAB color space; adjust the L*a*b* values on the L*a*, a*b*, and L*b* planes respectively to obtain different L*a*, a*b*, and L*b* values, and prepare 80 test samples according to the L*a*, a*b*, and L*b* values; the differences between the adjusted different L*, a*, b* values and the L*, a*, b* values of the standard sample are ≤ 1;

[0052] S2. Screening of color sample colors: Select 8 observers with normal vision. Under the test condition of GretagMacbeth The JudgeⅡ multi - light - source standard observation box in Day mode, the observers screen the test samples at a distance of about 45 cm from the color samples, with each color observed for 2 s. Require the observers to make a judgment on whether there is a color difference from the standard sample immediately, and obtain the samples with no visual color difference from the standard sample; take the maximum value of △L*, △a*, and △b* of the samples with no visual color difference as the collection point, and uniformly collect the L*a*b* values of 48 of the samples with no visual color difference around the center point;

[0053] S3. Data analysis of the product: Fit the data of the L * a * b * values obtained in step S2 on a computer to obtain the visual threshold range as shown in Figure 3 .

[0054] From Figure 3 it can be obtained and

[0055] Verify the color difference control method of Example 1. Combine the L * a * b * values of different batches of samples and the ΔL * , Δa * and Δb * with the standard sample to judge whether there is a color difference (test color difference) between the batch samples and the standard sample. Then, under the same screening conditions as in step S2 above, let the human eye judge whether there is a color difference (visual color difference) between the batch samples and the standard sample. The results are shown in Table 2 below.

[0056] Table 2. Results of visual color difference and test color difference of different batches in Example 2.

[0057] Specimen <![CDATA[L * > <![CDATA[a * > <![CDATA[b * > <![CDATA[ΔL * > <![CDATA[Δa * > <![CDATA[Δb * > Measured color difference Visual color difference Batch sample 1 81.54 23.72 1.44 0.33 0.12 0.06 Unqualified Unqualified Batch sample 2 81.38 24.15 1.70 0.17 0.31 0.2 Qualified Qualified Batch sample 3 81.27 24.04 1.95 0.06 0.20 0.45 Unqualified Unqualified

[0058] Example 3

[0059] A method for controlling color difference based on visual perception, comprising the following steps:

[0060] S1. Use a color difference meter to measure the L*a*b* values of the standard sample (a paint containing Pigment Green 7), where L * = 83.59, a * = -26.70, b * = -1.25, and record them on the L*a*, a*b*, and L*b* planes in the CIELAB color space; adjust the L*a*b* values on the L*a*, a*b*, and L*b* planes respectively to obtain different L*a* values, a*b* values, and L*b* values, and prepare 80 test samples according to the L*a* values, a*b* values, and L*b* values; the difference between the adjusted different L*, a*, b* values and the L*, a*, b* values of the standard sample ≤ 1;

[0061] S2. Screening of color sample colors: Select 8 visually normal persons as observers. Under the test conditions of the GretagMacbeth The JudgeⅡ multi-light source standard observation box in Day mode, the observers screen the test samples at a distance of about 50 cm from the color samples, and each color is observed for 2 s. The observers are required to make a judgment on whether there is a color difference from the standard sample at the first time to obtain samples with no visual color difference from the standard sample; take the maximum value of △L*, △a*, and △b* of the samples with no visual color difference as the acquisition point, and uniformly collect the L*a*b* values of 48 of the samples with no visual color difference around the center point;

[0062] S4. Data analysis of the product: Fit the data of L * a * b * values obtained in step S2 on a computer to obtain the visual threshold range as shown in Figure 3 shown.

[0063] Fit the data of L * a * b * values of the color samples obtained in S2 to obtain the visual threshold range as shown in Figure 4 shown

[0064] From Figure 4 it can be obtained and

[0065] Verify the color difference control method of Example 1, and combine the L * a * b* The value and ΔL with respect to the standard sample * , Δa * and Δb * , to determine whether the color difference between the batch sample and the standard sample (test color difference), and then under the same screening conditions as in step S2 above, use the human eye to judge whether there is a color difference between the batch sample and the standard sample (visual color difference). The results are shown in Table 3 below.

[0066] Table 3 Results of Visual Color Difference and Test Color Difference for Different Batches in Example 3

[0067] Specimen <![CDATA[L * > <![CDATA[a * > <![CDATA[b * > <![CDATA[ΔL * > <![CDATA[Δa * > <![CDATA[Δb * > Measured color difference Visual color difference Batch sample 1 83.79 -26.88 -0.99 0.20 0.18 0.26 Qualified Qualified Batch sample 2 83.13 -27.09 -1.45 0.46 0.39 0.20 Unqualified Unqualified Batch sample 3 83.37 -26.98 1.95 0.22 0.28 0.70 Unqualified Unqualified

[0068] In summary, the color difference control method based on human eye vision provided by the present invention can provide a visual threshold range. L*a*b* values that meet this range can achieve visual colorlessness. It can be used to control the visual color difference of products in production, and is applicable to controlling the color difference of pigments, coatings, inks, printed and dyed products, plastic products, papermaking, rubber products or ceramics. Therefore, it can be used in the production of colored products such as pigments and coatings, and use this color difference control method to judge the color difference during production.

[0069] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations, simplifications made without departing from the spirit and principle of the present invention shall be equivalent replacement methods and are all included in the protection scope of the present invention.

Claims

1. A method for color difference control, characterized in that: The following steps are involved: S1. Test the L*a*b* value of the standard sample and record it on the L*a*, a*b* and L*b* planes in the CIELAB color space; and take this as the center point, adjust the L*, a*, and b* values ​​on each plane around the center point on the L*a*, a*b* and L*b* planes to obtain different L*a* values, a*b* values ​​and L*b* values, and prepare 70 to 100 test samples according to the L*a* values, a*b* values ​​and L*b* values ​​obtained above; S2. The test samples are screened by several people with normal vision to obtain 36 to 60 samples evenly distributed around the center point that have no visual color difference with the standard sample, and the L*a*b* values ​​of the obtained samples are recorded; S3. The L*a*b* data collected in step S2 are fitted by a computer to form a 3D ellipsoidal figure, and the visual threshold range and L * 、a * 、b * The maximum value that can be offset; the L*a*b* value of the control batch sample is within the visual threshold range, so that the sample with the L*a*b* value has no visual color difference with the standard sample in step S1; the fitting equation is as follows: Among them, (x0, y0, z0) is the L*a*b* value of the standard sample, (x, y, z) is the L*a*b* value of the test sample, and a, b, and c represent the semi-axis lengths of the ellipsoid, respectively.

2. The method according to claim 1, characterized in that In step S1, the difference between the different L*, a*, b* values ​​obtained by adjustment and the L*, a*, b* values ​​of the standard sample is ≤1.

3. The method according to claim 1 or 2, characterized in that: In step S1, the angle between the straight line where the adjusted L*a* value, a*b* value and L*b* value are located on the L*a*, a*b* and L*b* planes and the horizontal axis or vertical axis of the plane is 10 to 30°.

4. The method according to claim 1, characterized in that: The number of people with normal vision in step S2 is 6 to 8.

5. The method according to claim 1 or 4, characterized in that: In the step S2, the screening is performed under a light source with an illumination of 1030-1040 lx and a color temperature of 6740-6750 K.

6. The method according to claim 5, characterized in that In the step S2, before the screening, the subjects with normal vision first adapt visually to the background color in the same visual range as the test sample during the screening; the adaptation time is ≥ 1 min.

7. The method according to claim 6, characterized in that In the step S2, during the screening, the subjects with normal vision observe each test sample for 2 to 3 seconds.

8. The method according to claim 7, characterized in that During the screening, the subjects with normal vision rest for 10 to 20 minutes after observing 30 to 40 test samples.

9. The method according to claim 7, characterized in that: In the step S2, during the screening, the distance between the person with normal vision and the test sample is 45 to 55 cm.

10. Use of the color difference control method according to any one of claims 1 to 9 in controlling the color difference of pigments, coatings, inks, printed and dyed products, plastic products, papermaking, rubber products or ceramics.

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