Damage evaluation method for cultural relic pigment

Abstract

The invention provides a cultural relic pigment damage evaluation method which can be applied to the technical field of cultural relic protection. The damage evaluation method comprises the following steps: obtaining chromatic aberration and ultraviolet-visible absorption spectra of a cultural relic pigment sample under a plurality of different exposure durations; determining a plurality of characteristic wavebands related to damage according to the second derivatives of the respective ultraviolet-visible absorption spectra of the plurality of different exposure durations; obtaining an evaluation index of cultural relic pigment damage by utilizing respective chromatic aberration of a plurality of different exposure durations and a plurality of characteristic wavebands related to the damage; and performing damage evaluation on the cultural relic pigment according to the cultural relic pigment damage evaluation index.

Description

Technical Field

[0001] This disclosure relates to the field of cultural relic protection technology, and more specifically to a method for evaluating the damage to cultural relic pigments. Background Technology

[0002] Cultural relics can suffer irreversible damage to varying degrees, necessitating reasonable damage assessment methods for effective preventative protection. Related technologies utilize color difference as an evaluation index for color damage to pigments used in cultural relics.

[0003] In realizing the concept of this invention, it was found that the related technology has at least the following problems: the color damage to the pigments of cultural relics caused by environmental factors is already quite severe, and it is not possible to carry out timely protection effectively. Summary of the Invention

[0004] According to a first aspect of this disclosure, a method for evaluating the damage of cultural relic pigments is provided. The method includes: obtaining the color difference and ultraviolet-visible absorption spectra of a cultural relic pigment sample under multiple different exposure times; determining multiple characteristic bands related to damage based on the second derivatives of the ultraviolet-visible absorption spectra for each of the multiple different exposure times; obtaining evaluation indicators for the damage of the cultural relic pigments using the color difference for each of the multiple different exposure times and the multiple characteristic bands related to damage; and evaluating the damage of the cultural relic pigments based on the aforementioned evaluation indicators.

[0005] According to embodiments of this disclosure, determining multiple damage-related characteristic bands based on the second derivatives of the UV-Vis absorption spectra of multiple different exposure times includes: calculating the second derivatives of the UV-Vis absorption spectra of the multiple different exposure times; calculating the difference between the multiple second derivatives at different bands; and determining the bands with differences greater than a threshold as the multiple damage-related characteristic bands.

[0006] According to embodiments of this disclosure, the above-mentioned evaluation index for the damage to cultural relic pigments by utilizing the color difference of multiple different exposure times and multiple characteristic bands related to damage includes: calculating the peak area integral of the ultraviolet-visible absorption spectrum at each exposure time in the multiple characteristic bands related to damage; performing partial least squares regression based on the color difference of the multiple different exposure times and the multiple peak area integrals to obtain a latent variable used to characterize the correlation between the peak area integral and the color difference, and the latent variable serving as the above-mentioned evaluation index.

[0007] According to embodiments of this disclosure, the partial least squares regression operation performed based on the color difference and peak area integrals of the multiple different exposure times to obtain the potential variables used to characterize the correlation between peak area integrals and color difference includes: obtaining the weights of multiple damage-related characteristic bands based on the color difference and peak area integrals of the multiple different exposure times; and obtaining the potential variables based on the peak area integral and weights of each damage-related characteristic band for the ultraviolet-visible absorption spectrum of each exposure time.

[0008] According to embodiments of this disclosure, obtaining the latent variable for each damage-related characteristic band based on the peak area integral and weight of the UV-Vis absorption spectrum for each exposure duration includes: standardizing the peak area integral of each damage-related characteristic band to obtain standardized peak area integrals of multiple damage-related characteristic bands; and obtaining the latent variable based on the sum of the product of the standardized peak area integrals and weights of each damage-related characteristic band.

[0009] According to embodiments of this disclosure, obtaining the color difference and ultraviolet-visible absorption spectrum of the cultural relic pigment sample under multiple different exposure times includes: conducting an illumination aging experiment on the cultural relic pigment sample to obtain the color difference and ultraviolet-visible absorption spectrum of the cultural relic pigment sample under multiple different exposure times.

[0010] According to embodiments of this disclosure, obtaining the color difference and ultraviolet-visible absorption spectrum of the cultural relic pigment sample under multiple different exposure times includes: testing the color parameters of the cultural relic pigment sample under different exposure times to obtain the color difference of each of the multiple different exposure times based on the color parameters of each of the multiple different exposure times; and testing the ultraviolet-visible absorption spectrum of the cultural relic pigment sample to obtain the ultraviolet-visible absorption spectrum of each of the multiple different exposure times.

[0011] According to embodiments of this disclosure, the above-mentioned testing of the ultraviolet-visible absorption spectrum of the above-mentioned cultural relic pigment sample to obtain the ultraviolet-visible absorption spectrum of each of the above-mentioned multiple different exposure times includes: using an ultraviolet-visible spectrophotometer to test the ultraviolet-visible absorption spectrum of the above-mentioned cultural relic pigment sample to obtain the ultraviolet-visible absorption spectrum of each of the above-mentioned multiple different exposure times.

[0012] According to an embodiment of this disclosure, the above-mentioned testing of the color parameters of the above-mentioned cultural relic pigment sample includes: testing the color parameters of the above-mentioned cultural relic pigment sample using a spectrophotometer.

[0013] According to an embodiment of this disclosure, the above-mentioned illumination aging test on the above-mentioned cultural relic pigment sample includes: placing the above-mentioned cultural relic pigment sample on an automatic rotating turntable in a test chamber to uniformly irradiate the surface of the above-mentioned cultural relic pigment sample.

[0014] According to embodiments of this disclosure, ultraviolet-visible absorption spectroscopy can be used to analyze color damage at the mechanistic level and predict early damage that cannot be captured by color difference. By utilizing the color difference of multiple exposure times and multiple characteristic bands related to damage, the macroscopic indicator of color damage, color difference, and the ultraviolet-visible absorption spectroscopy used to analyze color damage at the mechanistic level are combined to obtain an evaluation index that can comprehensively assess the damage to cultural relic pigments. For damage to cultural relic pigments caused by environmental factors, this method can more sensitively identify color damage to cultural relic pigments, helping to achieve timely early warning in the early stages of damage, thereby achieving effective preventive protection of pigments. Attached Figure Description

[0015] The foregoing contents, other objects, features, and advantages of this disclosure will become clearer from the following description of embodiments of this disclosure with reference to the accompanying drawings.

[0016] Figure 1 A schematic flowchart illustrating the operation of a method for evaluating damage to cultural relic pigments according to an embodiment of the present disclosure is shown.

[0017] Figure 2 A schematic diagram illustrating an experimental procedure according to an embodiment of the present disclosure is shown.

[0018] Figure 3 A schematic diagram of an experimental apparatus according to an embodiment of the present disclosure is shown.

[0019] Figure 4 A schematic diagram illustrating the color difference variation of madder pigment according to an embodiment of the present disclosure is shown.

[0020] Figure 5 The ultraviolet-visible absorption spectrum of madder pigment according to an embodiment of the present disclosure is illustrated schematically. Detailed Implementation

[0021] The embodiments of the present disclosure will now be described with reference to the accompanying drawings. However, it should be understood that these descriptions are exemplary only and are not intended to limit the scope of the disclosure. In the following detailed description, numerous specific details are set forth to provide a thorough understanding of the embodiments of the present disclosure for ease of explanation. However, it will be apparent that one or more embodiments may be practiced without these specific details. Furthermore, descriptions of well-known structures and techniques are omitted in the following description to avoid unnecessarily obscuring the concepts of the present disclosure.

[0022] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit this disclosure. The terms “comprising,” “including,” etc., as used herein indicate the presence of the stated features, steps, operations, and / or components, but do not exclude the presence or addition of one or more other features, steps, operations, or components.

[0023] All terms used herein (including technical and scientific terms) have the meanings commonly understood by those skilled in the art, unless otherwise defined. It should be noted that the terms used herein are to be interpreted in a manner consistent with the context of this specification, and not in an idealized or overly rigid way.

[0024] When using expressions such as "at least one of A, B and C", they should generally be interpreted in accordance with the meaning that is commonly understood by those skilled in the art (e.g., "a system having at least one of A, B and C" should include, but is not limited to, a system having A alone, a system having B alone, a system having C alone, a system having A and B, a system having A and C, a system having B and C, and / or a system having A, B and C, etc.).

[0025] Traditional calligraphy, paintings, and polychrome artifacts are precious cultural heritages. However, these artifacts are susceptible to irreversible damage of varying degrees, requiring appropriate damage assessment methods for effective preventative protection. The basic material used in these artifacts, pigments, are photosensitive and easily damaged by lighting. Furthermore, unsuitable storage or display environments, such as high temperatures and humidity, can also damage the pigments. Pigments used in these artifacts, including indigo and gamboge, can suffer discoloration and fading due to unsuitable environmental factors such as light, temperature, and humidity, thus diminishing the historical and artistic value of the artifacts.

[0026] The related technologies include microscopic evaluation indicators for lighting damage to silk artifacts, and methods for calculating the degree of lighting damage to materials by combining the relative spectral power distribution of the irradiation light source. The related technologies also include methods for monitoring lighting damage to painted artifacts by comprehensively considering the lighting damage patterns of pigments and substrates, providing a basis for the testing and selection of museum lighting products.

[0027] Color difference analysis uses color difference as an evaluation index for color damage to pigments in cultural relics. For example, it addresses color damage caused by lighting. Due to photochemical reactions, the microscopic molecular structure of pigments changes after exposure to light, resulting in macroscopic damage. However, color difference is an external manifestation of photochemical damage and cannot characterize microscopic changes. By the time color difference changes are detected, the color damage has already become quite severe, hindering timely conservation efforts.

[0028] To overcome the limitations of color difference methods in color damage assessment, infrared spectroscopy and Raman spectroscopy have been introduced. Infrared spectroscopy analyzes the vibrational energy level transitions caused by the absorption of infrared light at specific wavelengths, determining molecular structure and chemical bond information by analyzing the position and intensity of absorption peaks. Raman spectroscopy analyzes the inelastic scattering caused by the interaction of light and molecules, i.e., Raman scattering, obtaining molecular vibrational and rotational information by analyzing the frequency shift of the scattered light. However, in the damage testing of cultural relic pigment samples, the spectra obtained by infrared spectroscopy include not only the characteristic peaks of the pigment but also a large number of characteristic peaks of the binder and the substrate, which is not conducive to spectral analysis. For some pigments, the excitation light source used in Raman spectroscopy causes polar molecules to produce strong fluorescence, annihilating the detection signal and making it difficult to obtain spectral data in certain wavelength ranges. Therefore, infrared spectroscopy and Raman spectroscopy introduce other interference noise in the color damage assessment of cultural relic pigments, resulting in significant limitations.

[0029] The embodiments of this disclosure provide a method for evaluating the damage of cultural relic pigments. It proposes a comprehensive microscopic evaluation index from the perspective of damage mechanism, which is applicable not only to light damage, but also to damage caused by environmental factors such as temperature and humidity, and provides early warning of damage to cultural relic pigments.

[0030] Figure 1 A schematic flowchart illustrating the operation of a method for evaluating damage to cultural relic pigments according to an embodiment of the present disclosure is shown.

[0031] like Figure 1 As shown, the damage assessment method for cultural relic pigments includes operations S110 to S140.

[0032] By operating S110, the color difference and ultraviolet-visible absorption spectra of the cultural relic pigment samples under multiple different exposure times were obtained.

[0033] Color difference can transform the subjective perception of color change into measurable and comparable objective data. As a macroscopic indicator of damage to pigment samples of cultural relics, color difference can be used to classify the degree of color damage.

[0034] The material composition and concentration of cultural relic pigment samples can be analyzed by examining their ultraviolet-visible absorption spectra. Based on the electronic energy level transitions caused by the absorption of ultraviolet-visible light by molecules or ions, chromophores in cultural relic pigment samples can be identified and their concentrations revealed. Furthermore, the causes of color damage can be investigated, the functional groups causing the damage can be identified, and the damage mechanism can be qualitatively revealed, thus enabling the evaluation of color damage at the mechanistic level.

[0035] In operation S120, multiple characteristic bands related to damage are determined based on the second derivatives of the UV-Vis absorption spectra of multiple different exposure times.

[0036] By operating S130, the color difference of multiple exposure times and multiple characteristic bands related to damage are used to obtain evaluation indicators of pigment damage to cultural relics.

[0037] In operation S140, the damage to the pigments of cultural relics is evaluated based on the evaluation indicators for pigment damage.

[0038] According to embodiments of this disclosure, ultraviolet-visible absorption spectroscopy can be used to analyze color damage at the mechanistic level and predict early damage that cannot be captured by color difference. By utilizing the color difference of multiple exposure times and multiple characteristic bands related to damage, the macroscopic indicator of color damage, color difference, and the ultraviolet-visible absorption spectroscopy used to analyze color damage at the mechanistic level are combined to obtain an evaluation index that can comprehensively assess the damage to cultural relic pigments. For damage to cultural relic pigments caused by environmental factors, this method can more sensitively identify color damage to cultural relic pigments, helping to achieve timely early warning in the early stages of damage, thereby achieving effective preventive protection of pigments.

[0039] According to embodiments of this disclosure, by calculating the second derivatives of the UV-Vis absorption spectra of multiple different exposure times and the differences between the multiple second derivatives at different bands, bands with differences greater than a threshold can be identified as multiple characteristic bands related to damage.

[0040] According to embodiments of this disclosure, the absorption peaks in the original ultraviolet-visible absorption spectrum can be amplified by the second derivative of the ultraviolet-visible absorption spectrum, making the characteristic bands related to damage more prominent and easier to identify. It can also accurately determine the position, depth and width of the absorption peaks in the original ultraviolet-visible absorption spectrum.

[0041] According to embodiments of this disclosure, the peak area integrals of the UV-Vis absorption spectrum for each exposure duration are calculated across multiple damage-related characteristic bands. Partial least squares regression is performed based on the color difference for each of the multiple exposure durations and the multiple peak area integrals to obtain latent variables characterizing the correlation between peak area integrals and color difference; these latent variables serve as evaluation indicators.

[0042] According to embodiments of this disclosure, the spectral information of chromophores is represented by the peak area integral of characteristic bands related to damage, enabling simultaneous quantitative detection of chromophores and sensitive detection of changes in their microenvironment within complex systems. By calculating latent variables representing the correlation between peak area integral and color difference through partial least squares regression, the correlation between microscopic indicators of damage at the mechanistic level and macroscopic indicators of damage represented by color difference can be quantified. Using these latent variables as evaluation indicators, a comprehensive evaluation of color damage to cultural relic pigments can be achieved.

[0043] According to embodiments of this disclosure, weights for multiple damage-related characteristic bands are obtained based on the color differences of multiple different exposure times and multiple peak area integrals. For the UV-Vis absorption spectrum of each exposure time, latent variables are obtained based on the peak area integral and weight of each damage-related characteristic band.

[0044] According to embodiments of this disclosure, in partial least squares regression, by utilizing the color differences of multiple different exposure times, multiple characteristic bands related to damage are weighted and allocated. This can compress dimensionality, improve the signal-to-noise ratio, and obtain potential variables that can best explain the correlation between peak area integral and color difference, thereby making the prediction accuracy of damage evaluation indicators higher.

[0045] According to embodiments of this disclosure, the peak area integral of each damage-related characteristic band is standardized to obtain standardized peak area integrals of multiple damage-related characteristic bands. The latent variable is obtained by summing the product between the standardized peak area integral of each damage-related characteristic band and its weight.

[0046] For example, in At different exposure durations, we obtained Individual color differences and There are several ultraviolet-visible absorption spectra in the pigment samples of cultural relics. In the case of a characteristic band related to damage, The peak area integrals of the damage-related characteristic bands total One. Based on Individual color differences and A standardized peak area integral is obtained The weights of each damage-related feature band , ... .

[0047] according to The weights of each damage-related feature band , ... The UV-Vis absorption spectrum at the first exposure time is... Standardized peak area integral under a characteristic band related to damage , ... To obtain the potential variables under the first exposure duration It can be represented as:

[0048] (1).

[0049] according to The weights of each damage-related feature band , ... The UV-Vis absorption spectra at the second exposure time are in Standardized peak area integral under a characteristic band related to damage , ... To obtain the potential variables under the second exposure duration It can be represented as:

[0050] (2).

[0051] according to The weights of each damage-related feature band , ... And the UV-Vis absorption spectrum at the third exposure time Standardized peak area integral under a characteristic band related to damage , ... To obtain the potential variables under the third exposure duration It can be represented as:

[0052] (3).

[0053] According to embodiments of this disclosure, standardizing the area integral of each peak can eliminate dimensional and scale differences, improve numerical stability, and enable latent variables to more realistically reflect damage degree information, thereby improving the prediction accuracy of damage evaluation indicators.

[0054] According to embodiments of this disclosure, illumination aging experiments can be conducted on cultural relic pigment samples to obtain the color difference and ultraviolet-visible absorption spectra of the cultural relic pigment samples under multiple different exposure times.

[0055] According to embodiments of this disclosure, the color parameters of cultural relic pigment samples are tested under different exposure times to obtain the color difference of multiple different exposure times based on the color parameters of multiple different exposure times. The ultraviolet-visible absorption spectra of cultural relic pigment samples are then tested to obtain the ultraviolet-visible absorption spectra of multiple different exposure times.

[0056] According to embodiments of this disclosure, by testing color parameters and ultraviolet-visible absorption spectra, the obtained ultraviolet-visible absorption spectra contain pigment characteristic peaks but do not contain interfering information such as binder characteristic peaks and substrate characteristic peaks. The excitation light source used in the ultraviolet-visible absorption spectroscopy test will not cause polar molecules to fluoresce, thus affecting the identification of characteristic bands related to damage.

[0057] Figure 2 A schematic diagram illustrating an experimental procedure according to an embodiment of the present disclosure is shown.

[0058] like Figure 2 As shown, in operation S210, a cultural relic pigment sample is prepared. In operation S220, the sample is exposed to light in an experimental chamber. In operation S230, color and ultraviolet-visible absorption spectroscopy tests are performed on the cultural relic pigment sample at different exposure times. In operation S240, color difference data is obtained based on the color difference parameter test data. In operation S250, multiple characteristic bands related to damage are determined based on the ultraviolet-visible absorption spectroscopy test data. In operation S260, multiple peak area integrals are obtained based on the multiple characteristic bands related to damage. In operation S270, evaluation indicators are obtained using partial least squares regression.

[0059] In operation S210, in one example, the preparation of a cultural relic pigment sample can be performed as follows.

[0060] Multiple 1cm x 1cm square holes were cut into a 1.25mm thick, 10cm x 10cm square, single-sided adhesive plastic film, with a 0.5cm gap between each hole. The plastic film was then pasted onto a pre-mounted paper substrate, removing any air gaps between the film and the substrate. Gelatin and water were mixed at a 1:10 mass ratio and stirred until a gelatin solution was obtained. This solution was heated in a water bath at a constant temperature of 60℃ to prevent solidification. Artifact pigments were mixed with the gelatin solution at a 1:11 mass ratio in a palette to obtain a prepared pigment. The prepared pigment was then drawn up with a pipette and dripped into the square holes of the plastic film to obtain an artifact pigment sample, which was spread evenly to ensure smoothness. The artifact pigment sample was then left to dry in a dark environment with constant temperature and humidity for 30 days, maintaining an ambient temperature of 23℃ and an ambient humidity of 50±5%. After the color parameters of the artifact pigment sample stabilized, testing experiments were conducted to minimize experimental errors.

[0061] During the operation of S220, light exposure was performed in the experimental chamber.

[0062] Figure 3 A schematic diagram of an experimental apparatus according to an embodiment of the present disclosure is shown.

[0063] like Figure 3As shown, in one embodiment, the testing apparatus can be a temperature and humidity controlled lighting chamber with automatic temperature and humidity regulation. The temperature inside the chamber can be set to 20°C, and the air exchange rate can be set to 0.5 times per day. A 3000K color temperature LED (Light-Emitting Diode) light source is installed at the top of the chamber's interior. By adjusting the output power of the LED light source, the irradiance on the surface of the artifact pigment sample is made to 30W / m². 2 .

[0064] According to embodiments of this disclosure, a cultural relic pigment sample is placed on an automatic rotating turntable inside an experimental chamber to uniformly irradiate the surface of the sample. For example, the sample is placed on a platform at the bottom of the chamber, and an automatic rotating turntable is installed on the platform to rotate the sample at a speed of 0.5 revolutions per minute.

[0065] Using the S230, color and UV-Vis absorption spectroscopy tests were performed on artifact pigment samples at different exposure times. For example, the exposure times could be set as follows: first exposure time 0h, second exposure time 96h, and third exposure time 168h.

[0066] Under the illumination of a standard A light source calibrated by the National Institute of Metrology of China, the experimental operators, wearing specialized black work clothes, can test the color parameters of cultural relic pigment samples using a spectrophotometer, according to embodiments of this disclosure. According to embodiments of this disclosure, a UV-Vis spectrophotometer can be used to test the UV-Vis absorption spectrum of the cultural relic pigment samples, obtaining multiple UV-Vis absorption spectra for different exposure times. The spectral resolution of the UV-Vis spectrophotometer can be set to 2 mm, and the spectral range to 200 nm-800 nm. Each UV-Vis absorption spectrum is expressed in absorbance units.

[0067] When operating S240, color difference data is obtained based on the color difference parameter test data.

[0068] Figure 4 A schematic diagram illustrating the color difference variation of madder pigment according to an embodiment of the present disclosure is shown.

[0069] like Figure 4 As shown, for example, madder pigment underwent three different exposures: the first exposure was 0 hours, the second was 96 hours, and the third was 168 hours. The color parameters of madder pigment can be obtained using... Color coordinates are used to represent, Indicates brightness, Indicates the red-green axis. This indicates the yellow-blue axis. It can be used to represent the color parameters at the first exposure duration. , , ) is the initial value.

[0070] The color difference at the first exposure time can be expressed as: .

[0071] Color parameters at the second exposure time ( , , Color difference relative to the initial value It can be represented as:

[0072] (4).

[0073] Color parameters at the third exposure time ( , , Color difference relative to the initial value It can be represented as:

[0074] (5).

[0075] When operating the S250, based on ultraviolet-visible absorption spectroscopy test data, several characteristic bands related to damage were identified.

[0076] For example, after illumination aging tests, madder pigment showed significant changes in the following damage-related characteristic wavelengths: 237nm-251nm (hydroxyl-related) and 413nm-433nm (ketone-related).

[0077] Figure 5 The ultraviolet-visible absorption spectrum of madder pigment according to an embodiment of the present disclosure is illustrated schematically.

[0078] like Figure 5 As shown, madder pigment was exposed for three different durations: the first exposure was 0 hours, the second was 96 hours, and the third was 168 hours. Each UV-Vis absorption spectrum is expressed in absorbance units. The unit "au" is an abbreviation for "absorbance units," indicating that absorbance is a dimensionless quantity.

[0079] The degradation mechanism of madder pigment under illumination aging: In the 237nm-251nm wavelength range, the UV-Vis absorption spectrum at the first exposure time is the highest compared to the second and third exposure times. The absorbance in the 237nm-251nm wavelength range decreases slightly over time, indicating a weakening of the absorption peak related to hydroxyl groups in the chromophore, manifested as fading. In the 413nm-433nm wavelength range, the peak value changes significantly with considerable fluctuations, indicating a transition in the molecular structure of the chromophore, affecting the color development structure. In color coordinates , A decrease in color manifests as a change to green or blue.

[0080] The damage-related characteristic bands that showed significant changes were extracted using the second derivative and are consistent with the chromophore of madder pigment. The 237nm-251nm band corresponds to the hydroxyl group in the chromophore, and the 413nm-433nm band corresponds to the ketone group in the chromophore.

[0081] In operating S260, multiple peak area integrals are obtained based on multiple characteristic bands related to damage.

[0082] For example, peak area integrals are calculated based on the damage-related characteristic bands of madder pigment. Table 1 shows the peak area integrals of the UV-Vis absorption spectrum in the damage-related characteristic bands of madder pigment at the first exposure time (0 h), indicating that the madder pigment has not undergone illumination aging tests. Similarly, the peak area integrals of the damage-related characteristic bands after illumination aging tests at the second and third exposure times can be obtained.

[0083] Table 1

[0084]

[0085] In operation S270, partial least squares regression is used to obtain evaluation indicators.

[0086] Based on color difference detection data from three exposures at different durations and peak area integrals from the UV-Vis absorption spectra, partial least squares regression was performed to obtain the latent variables that best explain the correlation between peak area integrals and color difference for each exposure duration. latent variables As an evaluation index, it is used to comprehensively evaluate the damage to madder pigment.

[0087] Those skilled in the art will understand that the features described in the various embodiments of this disclosure can be combined and / or combined in various ways, even if such combinations or combinations are not explicitly described in this disclosure. In particular, the features described in the various embodiments of this disclosure can be combined and / or combined in various ways without departing from the spirit and teachings of this disclosure. All such combinations and / or combinations fall within the scope of this disclosure.

[0088] The embodiments of this disclosure have been described above. However, these embodiments are for illustrative purposes only and are not intended to limit the scope of this disclosure. Although various embodiments have been described above, this does not mean that the measures in the various embodiments cannot be used advantageously in combination. Various substitutions and modifications can be made by those skilled in the art without departing from the scope of this disclosure, and all such substitutions and modifications should fall within the scope of this disclosure.

Claims

1. A method for evaluating the damage to pigments used in cultural relics, characterized in that, The damage assessment method includes: Obtain the color difference and ultraviolet-visible absorption spectra of cultural relic pigment samples under multiple different exposure times; Based on the second derivatives of the UV-Vis absorption spectra of multiple different exposure times, several characteristic bands related to damage were determined. By utilizing the color difference of multiple exposure times and multiple characteristic bands related to damage, an evaluation index for pigment damage in cultural relics is obtained. The damage to the pigments in cultural relics is evaluated based on the aforementioned evaluation indicators.

2. The damage evaluation method according to claim 1, characterized in that, The determination of multiple damage-related characteristic bands based on the second derivatives of the UV-Vis absorption spectra of multiple different exposure times includes: Calculate the second derivative of the UV-Vis absorption spectra for each of the multiple different exposure times; Calculate the difference between multiple second derivatives at different wavebands; The bands with differences greater than a threshold are identified as the multiple characteristic bands related to damage.

3. The damage evaluation method according to claim 1, characterized in that, The evaluation indicators for pigment damage in cultural relics, obtained by utilizing the color differences of multiple exposure times and multiple characteristic bands related to damage, include: Calculate the peak area integral of the UV-Vis absorption spectrum for each exposure duration in the multiple damage-related characteristic bands; Based on the color difference of each of the multiple different exposure times and the multiple peak area integrals, partial least squares regression is performed to obtain latent variables that characterize the correlation between peak area integrals and color difference. These latent variables serve as the evaluation index.

4. The damage evaluation method according to claim 3, characterized in that, The partial least squares regression operation, performed based on the color difference of each of the multiple different exposure times and the multiple peak area integrals, yields the following latent variables used to characterize the correlation between peak area integrals and color difference: Based on the color difference of the multiple different exposure times and the integral of the multiple peak areas, the weights of multiple damage-related characteristic bands are obtained. For each exposure duration of the UV-Vis absorption spectrum, the latent variables are obtained based on the peak area integral and weight of each characteristic band associated with damage.

5. The damage evaluation method according to claim 4, characterized in that, The latent variables obtained for the UV-Vis absorption spectrum for each exposure duration, based on the peak area integral and weight of each damage-related characteristic band, include: The peak area integral of each damage-related characteristic band is standardized to obtain the standardized peak area integral of multiple damage-related characteristic bands. The latent variables are obtained by summing the standardized peak area integrals and weights of each damage-related characteristic band.

6. The damage evaluation method according to claim 1, characterized in that, The obtained color difference and ultraviolet-visible absorption spectra of the cultural relic pigment samples under multiple different exposure times include: An illumination aging experiment was conducted on the pigment samples of the cultural relics to obtain the color difference and ultraviolet-visible absorption spectra of the pigment samples under multiple different exposure times.

7. The damage evaluation method according to claim 1, characterized in that, The obtained color difference and ultraviolet-visible absorption spectra of the cultural relic pigment samples under multiple different exposure times include: At different exposure durations The color parameters of the pigment samples from the cultural relics were tested to obtain the color difference for each of the multiple exposure times based on the color parameters for each different exposure time. The ultraviolet-visible absorption spectra of the pigment samples of the cultural relics were tested to obtain the ultraviolet-visible absorption spectra of each of the multiple exposure times.

8. The damage evaluation method according to claim 7, characterized in that, The ultraviolet-visible absorption spectra of the pigment samples from the cultural relics were tested to obtain the ultraviolet-visible absorption spectra of each of the multiple exposure times, including: The ultraviolet-visible absorption spectra of the pigment samples of the cultural relics were tested using an ultraviolet-visible spectrophotometer to obtain the ultraviolet-visible absorption spectra of the samples with different exposure times.

9. The damage evaluation method according to claim 7, characterized in that, The testing of the color parameters of the pigment samples from the cultural relics includes: The color parameters of the pigment samples from the cultural relics were tested using a spectrophotometer.

10. The damage evaluation method according to claim 6, characterized in that, The illumination aging test on the pigment samples of the cultural relics includes: The cultural relic pigment sample is placed on an automatic rotating turntable inside the experimental chamber to uniformly irradiate the surface of the cultural relic pigment sample.

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