CN112051232A - Method for evaluating color change of gradient color sample - Google Patents
Method for evaluating color change of gradient color sample Download PDFInfo
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- CN112051232A CN112051232A CN202011027204.6A CN202011027204A CN112051232A CN 112051232 A CN112051232 A CN 112051232A CN 202011027204 A CN202011027204 A CN 202011027204A CN 112051232 A CN112051232 A CN 112051232A
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
- G01N21/17—Systems in which incident light is modified in accordance with the properties of the material investigated
- G01N21/25—Colour; Spectral properties, i.e. comparison of effect of material on the light at two or more different wavelengths or wavelength bands
- G01N21/31—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry
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Abstract
The invention discloses a method for evaluating color change of a gradient color sample, which comprises the following steps: before and after a sample test, respectively measuring the L, a and b values of the same area of a gradient sample by using a spectrophotometer, and calculating the color difference delta E according to the following formula;
wherein: l is0，a0，b0Represents the pre-test value; l is1，a1，b1Represents the value after the test; and judging the degree of color change according to the magnitude of the color difference delta E. The invention can accurately evaluate the color change of the gradient color sample.
Description
Technical Field
The invention belongs to the technical field of chromatic aberration test, and particularly relates to a method for evaluating color change of a gradient color sample.
Background
As the automotive color requirements become increasingly diverse, progressive color samples are becoming increasingly popular. How to evaluate and control the color of a fading sample becomes a concern for the automotive industry.
In the automobile industry, for the color change of a fading sample before and after a test, at present, subjective evaluation is relied on, the test sample is compared with a sample (reference sample) which is not tested, and the grade of a standard gray card is used as a final result. The method has the problems that subjective evaluation is influenced by factors such as human emotion, experience, environment and the like, and the consistency is slightly poor. In addition, the test sample and the reference sample are not the same sample, and a certain color difference exists, so that the evaluation result is not necessarily true color change.
For example, patent document CN103308173A discloses a method and an apparatus for measuring chromatic aberration, in which a high-definition camera is used to photograph a sample, and then software is used to analyze chromatic aberration. The disadvantage of this method is that the color of the sample cannot be reflected really by the camera photographing, and the problem of light reflection still exists when the sample with high glossiness is photographed.
Therefore, it is necessary to develop a new method for evaluating the color change of the gradation color sample.
Disclosure of Invention
The invention provides a method for evaluating the color change of a gradient color sample, which can accurately evaluate the color change of the gradient color sample.
The method for evaluating the color change of the gradual change color sample comprises the following steps:
before and after a sample test, respectively measuring the values L, a and b in the same area of a gradient sample by using a spectrophotometer, and calculating the color difference delta E according to the following formula;
wherein: l is0，a0,b0Represents the pre-test value; l is1，a1,b1Represents the value after the test;
and judging the degree of color change according to the magnitude of the color difference delta E.
Further, the spectrophotometer adopts a desk-top spectrophotometer; before measurement, marking a mark line on the back of the sample, wherein the size of the mark line is the same as that of a holder of a table-type spectrophotometer, and the holder is overlapped with the mark line for each measurement so as to realize the measurement of the same area.
Further, the spectrophotometer adopts a portable spectrophotometer; before measurement, marking a mark line on the front surface of the sample, wherein the size of the mark line is the same as that of the measurement end of the portable spectrophotometer, and the measurement end of the portable spectrophotometer is superposed with the mark line for each measurement so as to realize the measurement of the same area.
The invention has the following advantages: the color measurement of the same position of the gradient color sample before and after the test can be realized, and the color change degree of the gradient color sample can be judged by calculating the color difference before and after the test.
Drawings
FIG. 1 is a schematic diagram of a measurement performed by a stage spectrophotometer in the present embodiment;
FIG. 2 is a schematic diagram of a table spectrophotometer in this embodiment showing the labeling of a sample;
FIG. 3 is a schematic view of a marked line of a sample measured by the stage spectrophotometer in this embodiment;
FIG. 4 is a schematic view of a portable spectrophotometer measurement in this embodiment;
FIG. 5 is a schematic diagram of a portable spectrophotometer in this embodiment showing the labeling of a sample;
FIG. 6 is a schematic view of a marked line of a sample measured by the portable spectrophotometer in this embodiment;
in the figure: 1. the device comprises a desk type spectrophotometer, 2, a sample, 3, a clamp holder, 4, a marking tool, 5, a marking pen, 6, a marking line, 7, a portable spectrophotometer, 8 and a measuring end.
Detailed Description
The invention will be further explained with reference to the drawings.
In this embodiment, a method for evaluating a color change of a gradient color sample includes the following steps:
before and after the sample 2 test (such as an aging test), respectively measuring the values of L, a and b in the same area of the gradient color sample 2 by using a spectrophotometer, wherein L represents the brightness, the value is 0-100, and the larger the value is, the larger the brightness is; a. b has positive and negative values, + a represents red, a represents green, and + b represents yellow, and-b represents blue.
Calculating the color difference delta E according to the following formula;
wherein: l is0，a0,b0Represents the pre-test value; l is1，a1,b1Represents the value after the test;
and judging the degree of color change according to the magnitude of the color difference delta E.
In this embodiment, the spectral interval resolvable by the spectrophotometer for measuring color is as small as possible, the measurable range includes the range of visible light as much as possible, and the measurement aperture is as small as possible.
There are two types of commonly used spectrophotometers, a desktop spectrophotometer 1 and a portable spectrophotometer 7. When measuring color using the bench spectrophotometer 1, the sample 2 is held by the holder 3, and only the back of the sample 2 and the holder 3 are visible, see fig. 1. When the portable spectrophotometer 7 is used for color measurement, the sample 2 needs to be flatly placed on a table, and only the surface to be measured of the sample 2 and the measurement end 8 of the portable spectrophotometer 7 are visible, as shown in fig. 4.
As shown in fig. 2 and 3, with respect to the bench type spectrophotometer 1, only the back surface of the sample 2 and the holder 3 can be observed during the measurement. Before measurement, a marking line 6 is marked on the back of the sample 2, the size of the marking line 6 is the same as that of the holder 3 of the desktop spectrophotometer 1, and the holder 3 is overlapped with the marking line 6 for each measurement so as to realize the measurement of the same area. The method comprises the following steps: firstly, according to the size of a clamp holder 3, a marking tool 4 with the same size as the clamp holder 3 is manufactured, before measurement, the marking tool 4 is placed on the back of a sample 2, a marking pen 5 is used for drawing a line along the outer edge of the marking tool 4, and a marking line 6 is formed; removing the marking tool 4, enabling the holder 3 to coincide with the marking line 6 when the sample 2 is held by the holder 3, and starting measurement; thereafter, for each measurement, the gripper 3 is brought into register with the marking line 6.
As shown in fig. 5 and 6, with respect to the portable spectrophotometer 7, only the front surface of the sample 2 and the measuring end 8 of the portable spectrophotometer 7 can be observed during the measurement. Before measurement, a marking line 6 is marked on the front surface of the sample 2, and the size of the marking line is the same as that of a measuring end 8 of a portable spectrophotometer 7. For each measurement, the same region can be measured only by superposing the measuring end 8 and the marking line 6. The method comprises the following steps: according to the size of a measuring end 8 of a portable spectrophotometer 7, a marking tool 4 with the same size as the measuring end 8 is manufactured, before testing, the marking tool 4 is placed on the front face of a sample 2, a marking pen 5 is used for drawing a line along the outer edge of the marking tool 4, and a marking line 6 is formed; the marking tool 4 is removed, the measuring end 8 of the portable spectrophotometer 7 is overlapped with the marking line 6, and measurement is started; thereafter, for each measurement, the measuring end 8 is brought into coincidence with the marking line 6 to effect measurement of the same area.
Claims (3)
1. A method of evaluating a color change of a graduated color sample, comprising the steps of:
before and after the test of the sample (2), respectively measuring the values of L, a and b in the same area of the gradient color sample (2) by using a spectrophotometer, and calculating the color difference delta E according to the following formula;
wherein: l is0，a0,b0Represents the pre-test value; l is1，a1,b1Represents the value after the test;
and judging the degree of color change according to the magnitude of the color difference delta E.
2. The method of evaluating a color change of a gradient color sample according to claim 1, wherein: the spectrophotometer adopts a desk type spectrophotometer (1); before measurement, a marking line (6) is marked on the back of the sample (2), the size of the marking line (6) is the same as that of a clamp holder (3) of the table-type spectrophotometer (1), and the clamp holder (3) is overlapped with the marking line (6) for each measurement so as to realize the measurement of the same area.
3. The method of evaluating a color change of a gradient color sample according to claim 1, wherein: the spectrophotometer adopts a portable spectrophotometer (7); before measurement, a marking line (6) is marked on the front surface of the sample (2), the size of the marking line (6) is the same as that of a measuring end (8) of the portable spectrophotometer (7), and the measuring end (8) of the portable spectrophotometer (7) is overlapped with the marking line (6) for each measurement so as to realize measurement of the same area.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202011027204.6A CN112051232A (en) | 2020-09-25 | 2020-09-25 | Method for evaluating color change of gradient color sample |
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| Application Number | Priority Date | Filing Date | Title |
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| CN202011027204.6A CN112051232A (en) | 2020-09-25 | 2020-09-25 | Method for evaluating color change of gradient color sample |
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| CN112051232A true CN112051232A (en) | 2020-12-08 |
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|---|---|---|---|---|
| US20070181027A1 (en) * | 2005-10-14 | 2007-08-09 | Kyocera Mita Corporation | Misregistration judging method, registration mark for color printing, color slippage detection mark, color slippage correction chart, color registration correction chart color slippage detection method color slippage correction |
| JP2008196887A (en) * | 2007-02-09 | 2008-08-28 | Toyota Motor Corp | Method for evaluating discoloration of coating film to be evaluated, and method for designing composition of color pigment |
| CN103308173A (en) * | 2013-05-21 | 2013-09-18 | 北京化工大学 | Color difference measuring method and device |
| US20150243471A1 (en) * | 2014-02-25 | 2015-08-27 | Weatherford/Lamb, Inc. | Alignment Marking for Rock Sample Analysis |
| CN106052876A (en) * | 2016-07-19 | 2016-10-26 | 北京印刷学院 | Light pole laser paper and printed matter color difference measurement method |
| WO2017022004A1 (en) * | 2015-07-31 | 2017-02-09 | 株式会社 日立ハイテクノロジーズ | Method for measuring pattern height and device for measuring pattern height |
| CN110296667A (en) * | 2019-08-13 | 2019-10-01 | 南昌航空大学 | High reflection surface method for three-dimensional measurement based on line-structured light multi-angle projection |
-
2020
- 2020-09-25 CN CN202011027204.6A patent/CN112051232A/en not_active Withdrawn
Patent Citations (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US20070181027A1 (en) * | 2005-10-14 | 2007-08-09 | Kyocera Mita Corporation | Misregistration judging method, registration mark for color printing, color slippage detection mark, color slippage correction chart, color registration correction chart color slippage detection method color slippage correction |
| JP2008196887A (en) * | 2007-02-09 | 2008-08-28 | Toyota Motor Corp | Method for evaluating discoloration of coating film to be evaluated, and method for designing composition of color pigment |
| CN103308173A (en) * | 2013-05-21 | 2013-09-18 | 北京化工大学 | Color difference measuring method and device |
| US20150243471A1 (en) * | 2014-02-25 | 2015-08-27 | Weatherford/Lamb, Inc. | Alignment Marking for Rock Sample Analysis |
| WO2017022004A1 (en) * | 2015-07-31 | 2017-02-09 | 株式会社 日立ハイテクノロジーズ | Method for measuring pattern height and device for measuring pattern height |
| CN106052876A (en) * | 2016-07-19 | 2016-10-26 | 北京印刷学院 | Light pole laser paper and printed matter color difference measurement method |
| CN110296667A (en) * | 2019-08-13 | 2019-10-01 | 南昌航空大学 | High reflection surface method for three-dimensional measurement based on line-structured light multi-angle projection |
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