Method and system for evaluating the degree of deterioration of a cultural heritage object made of leather
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2024-07-02
- Publication Date
- 2026-08-11
Smart Images
Figure CN118655304B_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of leather cultural relic protection technology, specifically relating to a method and system for rating the degree of deterioration of leather cultural relics. Background Technology
[0002] Humans have a long history of using leather products, and leather artifacts can reflect the cultural characteristics and social customs of their time, making them extremely valuable for research. After long-term preservation or burial, leather artifacts often undergo significant structural changes. Internal substances such as moisture, collagen, and oils are lost or denatured to varying degrees, resulting in deterioration phenomena such as hardening, mold, curling, and cracking. Timely assessment of the deterioration state of leather artifacts and the implementation of effective restoration and protection measures are crucial for their long-term preservation. However, current methods largely focus on evaluating the deterioration of leather artifacts from a sensory perspective, lacking a quantitative assessment method for the degree of deterioration. Therefore, there is an urgent need to establish a scientific and accurate method for grading the degree of deterioration of leather artifacts. Summary of the Invention
[0003] To address the problems in the background art, the present invention provides a method and system for rating the degree of deterioration of leather cultural relics.
[0004] To achieve the above objectives, the first solution provided by the present invention is as follows: The method for grading the degree of deterioration of leather artifacts includes: Obtain electronic images of leather artifacts; The layout of the acquisition points is calculated and optimized based on the image to obtain the optimized acquisition points; The moisture content of leather artifacts was detected at the optimized sampling points, and the weighted average moisture content was calculated. To obtain the hydroxyproline content and microstructure of leather artifacts; The degree of deterioration of leather artifacts is assessed based on the weighted average of the moisture content, hydroxyproline content, and microstructure.
[0005] Preferably, the method for calculating the layout of acquisition points based on the image is as follows: The image outline is obtained by analyzing the image dimensions; Calculate the maximum length and width based on the image outline and create the corresponding rectangle; Starting from the center point of the rectangle, set a sampling point at a preset distance until the entire area of leather artifacts is covered.
[0006] Preferably, the method for optimizing the layout of acquisition points is as follows: based on image depth, brightness or other relevant image parameters, a detection area with high confidence is identified, and the layout of acquisition points is adjusted so that all acquisition points fall within the detection area with high confidence.
[0007] Preferably, the method for identifying the highly reliable detection area is as follows: acquiring leather images of the leather artifact at the camera's focal plane, the foreground depth boundary, and the background depth boundary, removing the blurred areas from the three leather images, and merging the finally retained clear areas.
[0008] Preferably, the weighted average value of the moisture content is calculated using the following formula: ; where x i The moisture content at each sampling point, n is the optimal number of sampling points, and f i Preset weights.
[0009] Preferably, the method for assessing the deterioration level of leather artifacts based on the weighted average of the moisture content, hydroxyproline content, and microstructure is as follows: The weighted average value of the moisture content, the hydroxyproline content, and the microstructure are assigned values according to preset standards to obtain moisture content scores, hydroxyproline content scores, and microstructure scores. According to the degradation scoring formula, the degradation score is calculated based on the moisture content score, hydroxyproline content score, and micromorphology score. By correlating the degradation score with a preset degradation level, the degradation level of the leather artifact is obtained.
[0010] Preferably, the degradation scoring formula is S i = 0.1633S1+0.5397S2+0.297S3, where S1 is the microstructure score, S2 is the moisture content score, and S3 is the hydroxyproline content score.
[0011] The second technical solution adopted in this invention is: A grading system for the deterioration of leather artifacts includes: The first acquisition module is used to acquire electronic images of leather artifacts; The calculation module is used to calculate and optimize the layout of the acquisition points based on the image to obtain the optimized acquisition points; The detection and calculation module is used to detect the moisture content of leather artifacts at the optimized collection points and calculate the weighted average of the moisture content. The second acquisition module is used to acquire the hydroxyproline content and microstructure of leather artifacts. An assessment module is used to evaluate the deterioration level of leather artifacts based on the weighted average of the moisture content, hydroxyproline content, and microstructure.
[0012] Compared with the prior art, the present invention has the following beneficial effects: This invention uses the moisture content, hydroxyproline content, and micromorphology of leather artifacts as indicators. By calculating the weights among these three factors, a deterioration scoring formula is established. In the actual rating process, by measuring the above three indicators, an accurate assessment of the deterioration level of leather artifacts can be achieved.
[0013] This invention optimizes the sampling points during the moisture content detection of leather artifacts, improving the accuracy of moisture detection results and enabling accurate assessment of the degree of deterioration. Attached Figure Description
[0014] Figure 1 The test results of simulated samples of leather cultural relics with different degrees of deterioration provided in the embodiments of the present invention; Figure 2 A flowchart illustrating the method for rating the degree of deterioration of leather artifacts provided in an embodiment of the present invention; Figure 3 A schematic diagram of a device for acquiring images of leather artifacts according to a preferred embodiment of the present invention; Figure 4 A schematic diagram showing the position of a leather artifact on the camera's focal plane, at the foreground depth of field boundary, and at the background depth of field boundary, according to a preferred embodiment of the present invention. Figure 5 Simulated samples of leather artifacts with different degrees of deterioration provided in embodiments of the present invention; Figure 6 The test data of moisture content (a) and hydroxyproline content (b) of simulated leather cultural relics provided in the embodiments of the present invention, as well as the classification of deterioration level ranges; Figure 7 A schematic diagram of the structure of the leather artifact deterioration rating system provided in an embodiment of the present invention. Detailed Implementation
[0015] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.
[0016] The main components of leather artifacts are collagen and water, with water helping to maintain the healthy structure of the collagen fiber network. Deterioration damages this network and reduces the leather's water-retention capacity. As the leather loses moisture, it gradually becomes dry, hard, and brittle. Therefore, moisture content is closely related to the degree of leather deterioration. Except for leather buried in extremely dry or water-saturated environments, the moisture content of finished leather generally remains between 12% and 18%. When leather artifacts are stored in museums, the temperature and humidity are usually constant. Therefore, the moisture content of leather artifacts primarily depends on their water-retention capacity and can serve as an important indicator of their degree of deterioration.
[0017] While the moisture content of leather artifacts can reflect their degree of deterioration and preservation condition, judging the degree of deterioration of leather based on a single indicator is prone to bias due to accidental factors, making it difficult to guarantee the accuracy of the final result. To make the deterioration rating method more universal, accurate, and reasonable, it is necessary to combine other indicators to comprehensively judge the degree of deterioration of leather artifacts.
[0018] When leather deteriorates, its chemical composition, physical properties, and collagen fiber network morphology all change. To establish a method for grading the degree of deterioration of leather artifacts and to identify indicators closely related to the degree of deterioration, the applicant first used antique iron-tanned leather as raw material and prepared a series of simulated leather artifact samples with different degrees of deterioration using a rapid composting aging method. The samples are numbered 1-6. Figure 1 Sample 1 was untreated leather, and the degree of deterioration gradually increased from 1 to 6. The macroscopic morphology of the surface and cross-section was observed using a stereomicroscope, the microscopic morphology of the cross-section was observed using a scanning electron microscope (SEM), the morphology and porosity of the samples were detected using a micro-computed tomography (microCT) system, the moisture content was detected using a skin moisture meter, and the hydroxyproline content was determined using high-performance liquid chromatography-fluorescence detection. The results are as follows: Figure 1 As shown.
[0019] Stereomicroscopic images show that as the degree of deterioration increases, the leather surface darkens and becomes rougher; the distinction between the grain and reticular layers at the cross-section gradually blurs, and the adhesion of collagen fibers increases; the leather thickness decreases. Although the macroscopic morphology of the leather is clearly correlated with the degree of deterioration, it is difficult to obtain characteristic information for judging the degree of deterioration from macroscopic morphology alone, and therefore it is not suitable as a key indicator for judging the degree of deterioration. Micro-CT detection results show that as the degree of deterioration increases, the porosity of the sample gradually decreases, and the leather gradually becomes denser and more cohesive from a loose and porous state. However, the porosity of leather is easily affected by tanning processes (such as tanning), and the initial value often varies and the change value fluctuates greatly; therefore, it is also not suitable as a quantitative indicator for judging the degree of deterioration.
[0020] SEM images reveal that the collagen fiber structure of unaged leather samples remains intact, exhibiting a distinct "D-cycle," characterized by periodic light and dark horizontal striations formed by the staggered arrangement of one-quarter of the protoplasmic collagen fibers. As degradation increases, collagen fiber bundles begin to break and fracture, subsequently destroying the fiber structure and reducing the clarity of the "D-cycle." In other words, the collagen fiber structure is progressively damaged with increasing degradation. Therefore, characteristic information about the leather can be obtained from SEM images, allowing for the assessment of the degree of degradation in leather artifacts.
[0021] As leather artifacts deteriorate, they gradually lose collagen and their ability to retain moisture decreases. Figure 1 It can be seen that the moisture content and hydroxyproline content of leather are negatively correlated with the degree of deterioration. As mentioned earlier, the moisture content of leather artifacts in museum collections is primarily related to their water-retention capacity; hydroxyproline is a characteristic amino acid of collagen, and its proportion in collagen remains relatively stable. Therefore, the moisture content and hydroxyproline content of leather can be used to quantify the degree of leather deterioration.
[0022] Based on the above research, the first embodiment of the present invention provides a method for rating the degree of deterioration of leather cultural relics. Figure 2 This is a flowchart illustrating the method for rating the degree of deterioration of leather artifacts provided in an embodiment of the present invention.
[0023] like Figure 2 As shown, the method for grading the degree of deterioration of leather artifacts specifically includes the following steps: S101, Acquire electronic images of leather artifacts.
[0024] Understandably, leather artifacts can be directly scanned to obtain electronic images that reflect their basic outline and size. These electronic images are then used to confirm the sampling points for subsequent moisture content testing.
[0025] S102, calculate and optimize the layout of the acquisition points based on the image to obtain the optimized acquisition points.
[0026] The calculation of the collection point layout may include: analyzing the image size to obtain the image outline; calculating the maximum length and width based on the image outline and making a corresponding rectangle; setting a collection point at a preset distance from the center point of the rectangle until the entire leather artifact area is covered.
[0027] Understandably, those skilled in the art can select the preset distance based on the size, shape, and other characteristics of the leather artifact.
[0028] Because leather artifacts come in various shapes, they may contain irregular areas such as bends, folds, depressions, and protrusions. These areas may not meet the basic requirements for testing, and the accuracy of test results in these areas is questionable. Therefore, it is necessary to exclude these areas. High-confidence detection areas can be identified based on image depth, brightness, or other relevant image parameters. The layout of the acquisition points can then be adjusted to remove acquisition points in bends, folds, obvious depressions, or protrusions, ensuring that all acquisition points fall within high-confidence detection areas, thus optimizing the acquisition point selection.
[0029] In some preferred embodiments, the method for identifying the highly reliable detection area is as follows: acquiring leather images of the leather artifact at the camera's focal plane, the foreground depth boundary, and the background depth boundary, removing the blurred areas from the three leather images, and merging the finally retained clear areas.
[0030] Specifically, such as Figure 3-4 As shown, Figure 3 A preferred device for acquiring images of leather artifacts mainly consists of a camera 1 (preferably a small depth-of-field camera), a movable platform 2 for placing the leather artifact (hereinafter referred to as the stage), and a laser rangefinder 3. The acquisition method is as follows: The average height between the laser rangefinder 3 and the stage 2 is obtained as the base height value L0; the leather artifact 4 is placed on the stage 2, and the laser rangefinder 3 scans the leather artifact 4 to obtain the height values h of each area of the leather artifact 4; all height values h are statistically analyzed, and the height values are sorted to find the data segment with the smallest variance. The average height value a of the height data in this segment is calculated, i.e., the average height value a of the flat area; the depth of field ∆L from the camera 1 to the plane 5 where the focus center point is located is calculated; the stage is moved upwards in the vertical direction by L0-a-∆L / 2 (…). Figure 4 a), L0-a ( Figure 4 b), and the distance between L0-a+∆L / 2 ( Figure 4 c) That is, the flat areas with average height values are located at the camera's focus plane, the foreground depth of field, and the background depth of field. Leather images corresponding to the three locations are acquired, and all blurred areas on the three images are removed. The clear areas that are finally retained are merged as the reliable areas with high flatness, which are the detection areas with high reliability.
[0031] The formula for calculating depth of field is: Where σ is the radius of the dispersion circle, f For the lens focal length, F This is the aperture value used when the lens is shooting. L This is the focusing distance.
[0032] S103, detect the moisture content of leather artifacts at the optimized sampling points and calculate the weighted average of the moisture content.
[0033] Currently, common methods for detecting the moisture content of leather include oven drying and Karl Fischer titration. However, these methods are highly destructive to the samples and are not suitable for precious leather artifacts. In developing this invention, the applicant discovered that a skin moisture meter can be used for non-destructive testing of the moisture content of leather artifacts. By placing a moisture detection probe on the surface of the leather artifact, non-destructive testing of its moisture content can be achieved.
[0034] To reduce the impact of outlier data on moisture content results, it is necessary to calculate a weighted average of the moisture content of the optimized collection points.
[0035] Specifically, all the detected moisture content data are sorted by size, the median m is found, and the x value for each data point is calculated. i The ratio a to the median m i (a) i =x i / m), determine the weight f of each data point by referring to Table 1. i .
[0036] Table 1. Weighting Reference Table for Moisture Content Data .
[0037] Calculate the weighted average of the leather moisture content, and use this value as the final leather moisture content value. This reduces the impact of special areas and outlier data on the average moisture content result, making the result more accurate.
[0038] The formula for calculating the weighted average moisture content of leather is: .
[0039] S105, to obtain the hydroxyproline content and microstructure of leather artifacts.
[0040] Understandably, SEM can be used to acquire and observe the microscopic morphology of leather artifacts.
[0041] For measuring the hydroxyproline content in leather artifacts, existing methods for detecting hydroxyproline content in leather can be used, such as high performance liquid chromatography-fluorescence detection and p-dimethylaminobenzaldehyde colorimetric method.
[0042] S106, assess the deterioration level of leather artifacts based on the weighted average of the moisture content, hydroxyproline content, and microstructure.
[0043] This step specifically includes: S106-1, the weighted average value of the moisture content, the hydroxyproline content, and the microstructure are assigned values according to preset standards to obtain the moisture content score, the hydroxyproline content score, and the microstructure score.
[0044] In one specific implementation, the method for assigning values according to a preset standard is as follows: To assign values to moisture and hydroxyproline content, the proposed degradation levels of leather are divided into four grades: 0, I, II, and III. Grade 0 represents leather with no degradation, and the degree of degradation increases sequentially from grade 0 to grade III. To determine the corresponding ranges for hydroxyproline and moisture content for each degradation level, a large number of simulated samples need to be analyzed and tested. Figure 5 As shown, four simulated leather artifacts with different degrees of deterioration were selected, with four samples for each degree of deterioration, for a total of 16 samples. The hydroxyproline and moisture content of each sample were measured, and the experimental results are as follows. Figure 6 As shown in Table 2, the value range of each degradation interval was determined based on the value characteristics of the samples, and corresponding scores were assigned to each degradation level.
[0045] Table 2. Value ranges and assignments for each degradation level of moisture content and hydroxyproline content. .
[0046] Regarding the assignment of microscopic morphology values, undeteriorated leather collagen fibers exhibit a complete structure and a light-dark alternating "D-cycle" structure; as the degree of deterioration increases, the fibers become damaged and broken, and the clarity of the "D-cycle" decreases. This can be used to determine the degree of leather deterioration. Specific grading, descriptions, and example images are shown in Table 3.
[0047] Table 3 Classification and description of micromorphological degradation levels
[0048] .
[0049] It should be noted that the specific values, corresponding grades, moisture content, hydroxyproline content, and micromorphological descriptions assigned in the above process are all exemplary and do not require special limitation. Those skilled in the art can make adjustments according to the actual situation.
[0050] S106-2, Calculate the degradation score based on the moisture content score, hydroxyproline content score, and microstructure score according to the degradation scoring formula.
[0051] The degradation scoring formula in this embodiment of the invention was independently constructed by the applicant, and the specific method is as follows: When using moisture content, hydroxyproline content, and microstructure as indicators of the deterioration of leather artifacts, it is necessary to determine the weight of each indicator in the final decision-making process. The weight of each indicator is calculated using the analytic hierarchy process (AHP): Target layer Z: Determine the degree of deterioration of leather artifacts; Criterion layer A: Microstructure (A1), moisture content (A2), and hydroxyproline content (A3).
[0052] (1) Construct a judgment matrix A, and compare the relative importance a of each indicator pairwise. ij a ij a represents the importance of indicator i compared to indicator j. ij The value range is 1 to 9, and the definitions are shown in Table 4. If the judgment of the difference between indicators falls between two levels, a... ij The value of can be 2, 4, 6, or 8. Also, 'a'... ij ·a ji =1, a ii =1.
[0053] Table 4a ij Values and corresponding descriptions .
[0054] (2) The constructed judgment matrix A is shown in Table 5. Calculate the eigenvector w and the largest eigenvector λ of matrix A. max Consistency checks are performed to determine the weight of each indicator.
[0055] Table 5 Judgment Matrix A .
[0056] Maximum eigenvalue λ max =3.00875.
[0057] (3) Consistency check of matrix A The consistency index (CI) is calculated using the following formula. ; The calculated CI is 0.004375. Looking up the table, when n=3, the average random consistency index RI is 0.52. Calculate the conformity ratio (CR) using the following formula, and then perform a conformity check. ; Since CR = 0.0084 < 0.1, the consistency of the matrix is considered acceptable.
[0058] (4) Determination of indicator weights The eigenvectors of the matrix are w = (0.081, 0.731, 0.188). TThe corresponding values represent the weights of each indicator. Specifically, the weight for micromorphology is n1 = 0.1633, the weight for moisture content is n2 = 0.5397, and the weight for hydroxyproline content is n3 = 0.297.
[0059] Therefore, the degradation scoring formula of the embodiments of the present invention is: S i = 0.1633S1+0.5397S2+0.297S3, where S1 is the microstructure score, S2 is the moisture content score, and S3 is the hydroxyproline content score.
[0060] The degradation score can be obtained by substituting the detected moisture content score, hydroxyproline content score, and micromorphology score into the degradation scoring formula.
[0061] S106-3, The degradation score is matched with the preset degradation level to obtain the degradation level of the leather artifact.
[0062] Table 6 shows the scoring ranges corresponding to each deterioration level of leather artifacts in this embodiment of the invention. The final deterioration score S is... i The degradation level is determined by comparing with Table 6.
[0063] Table 6 Leather Deterioration Grade Classification and Scoring Range .
[0064] Using the methods described above, the applicant assessed the degree of deterioration of the self-prepared leather artifact simulation samples, and the results are shown in Table 7.
[0065] Table 7. Deterioration Assessment Results and Final Deterioration Level of Simulated Leather Artifact Samples .
[0066] A second aspect of this invention provides a rating system for the degree of deterioration of leather artifacts. Figure 7 This is a schematic diagram of the structure of the leather artifact deterioration rating system provided in the embodiments of this application.
[0067] The leather artifact deterioration grading system 700 includes a first acquisition module 701, a calculation module 702, a detection and calculation module 703, a second acquisition module 704, and an evaluation module 705. Details are as follows: The first acquisition module 701 is used to acquire electronic images of leather artifacts; The calculation module 702 is used to calculate and optimize the layout of the acquisition points based on the image to obtain the optimized acquisition points; The detection and calculation module 703 is used to detect the moisture content of leather artifacts at the optimized collection points and calculate the weighted average of the moisture content. The second acquisition module 704 is used to acquire the hydroxyproline content and microstructure of leather artifacts. Evaluation module 705 is used to evaluate the deterioration level of leather artifacts based on the weighted average of the moisture content, hydroxyproline content, and micromorphology.
[0068] The above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application.
Claims
1. A method for grading the degree of deterioration of leather cultural relics, characterized in that, Include: Obtain electronic images of leather artifacts; The layout of the acquisition points is calculated and optimized based on the image to obtain the optimized acquisition points; The moisture content of leather artifacts was detected at the optimized sampling points, and the weighted average moisture content was calculated. To obtain the hydroxyproline content and microstructure of leather artifacts; The weighted average value of the moisture content, the hydroxyproline content, and the microstructure are assigned values according to preset standards to obtain moisture content scores, hydroxyproline content scores, and microstructure scores. According to the degradation scoring formula, the degradation score is calculated based on the moisture content score, hydroxyproline content score, and micromorphology score. The degradation score is matched with a preset degradation level to obtain the degradation level of the leather artifact; The method for optimizing the layout of acquisition points is as follows: based on the image depth, brightness or other relevant image parameters, identify the detection area with high confidence, and adjust the layout of acquisition points so that all acquisition points fall within the detection area with high confidence. The method for identifying highly reliable detection areas is as follows: collect leather images of the leather artifacts at the camera's focal plane, the foreground depth boundary, and the background depth boundary, remove the blurred areas from the three leather images, and merge the finally retained clear areas.
2. The method for grading the degree of deterioration of leather cultural relics as described in claim 1, characterized in that, The method for calculating the layout of acquisition points based on the image is as follows: The image outline is obtained by analyzing the image dimensions; Calculate the maximum length and width based on the image outline and create the corresponding rectangle; Starting from the center point of the rectangle, set a sampling point at a preset distance until the entire area of leather artifacts is covered.
3. The method for rating the degree of deterioration of leather artifacts as described in claim 1, characterized in that, The weighted average of the moisture content is calculated using the following formula: ; where x i The moisture content at each sampling point, n is the optimal number of sampling points, and f i Preset weights.
4. The method for grading the degree of deterioration of leather cultural relics as described in claim 1, characterized in that, The deterioration score formula is S = 0.1633S1+0.5397S2+0.297S3, where S1 is a microtopography score, S2 is a moisture content score, and S3 is a hydroxyproline content score. i = 0.1633S1+0.5397S2+0.297S3, where S1 is a microtopography score, S2 is a moisture content score, and S3 is a hydroxyproline content score.
5. A rating system for the degree of deterioration of leather cultural relics, characterized in that, Include: The first acquisition module is used to acquire electronic images of leather artifacts; The calculation module is used to calculate and optimize the layout of the acquisition points based on the image to obtain the optimized acquisition points; The detection and calculation module is used to detect the moisture content of leather artifacts at the optimized collection points and calculate the weighted average of the moisture content; it is also used to identify high-confidence detection areas based on the image depth, brightness, or other relevant image parameters, and to adjust the layout of the collection points so that all collection points fall within the high-confidence detection areas. This is used to separately acquire leather images of leather artifacts at the camera's focal plane, the foreground depth of field boundary, and the background depth of field boundary, remove blurry areas from the three leather images, and merge the final clear areas. The second acquisition module is used to assign values to the weighted average of the moisture content, the hydroxyproline content, and the microstructure according to preset standards to obtain moisture content scores, hydroxyproline content scores, and microstructure scores; calculate the deterioration score under the moisture content score, hydroxyproline content score, and microstructure score according to the deterioration scoring formula; and match the deterioration score with the preset deterioration level to obtain the deterioration level of the leather artifact.