Pig leather, cow leather or sheep leather identification method based on Micro-CT technology

Abstract

A pig leather, cow leather or sheep leather identification method based on Micro-CT technology relates to the technical field of leather identification, and comprises the following steps: (1) carrying out Micro-CT scanning on a leather sample to obtain a three-dimensional image of the leather sample; (2) performing virtual slicing on the three-dimensional image by using analysis software to obtain a longitudinal section image of the internal structure of the leather sample; (3) observing the condition that the hair follicles penetrate through the leather body in the longitudinal section image, and measuring the inclined included angle between the hair follicles and the grain surface; (4) if the hair follicles penetrate through the leather body, judging that the leather is pig leather; if the hair follicles do not penetrate through the leather body and the inclined included angle is 23-30 degrees, judging that the leather is cattle leather; and if the hair follicles do not penetrate through the leather body and the inclined included angle is 13-20 degrees, determining that the leather is sheep leather. According to the method, the internal three-dimensional structure of the leather can be deeply detected without slicing treatment, and high-efficiency nondestructive identification of pig leather, cow leather or sheep leather is realized.

Description

Technical Field

[0001] The present invention relates to the technical field of leather identification, and in particular to a method for identifying pig leather, cow leather or sheep leather based on Micro-CT technology. Background Art

[0002] Leather refers to a natural biomaterial product made by processing animal hides and skins through physical and chemical methods to stabilize the hide's collagen fiber structure, resulting in durability, flexibility, and practical performance. With the advancement of synthetic materials technology, imitation leather materials like polyurethane and polyvinyl chloride have achieved surface morphology, mechanical properties, and even microscopic pore structure that closely mimic natural leather through surface treatment techniques like embossing and laser engraving. This has led to the phenomenon of "fakes being passed off as genuine" and "inferior goods being passed off as superior goods" in the market. To eliminate this phenomenon, it is necessary to establish scientific and reliable identification technology standards and evaluation systems.

[0003] Commonly used leather identification methods include sensory analysis, chemical analysis, optical microscopy, infrared spectroscopy, and molecular biology techniques. However, these methods all have significant limitations, and test results are often affected by the animal species, processing technology, and testing conditions. For example, sensory analysis relies on the experience and sensory judgment of the inspector, observing characteristics such as the leather's texture, feel, and odor. While this method is simple and quick, it is highly subjective, requires high standards from the inspector, and fails to provide objective, quantitative data.

[0004] Chemical analysis detects specific chemical components in leather for identification. Patent document CN109541193A discloses a qualitative analysis method for leather. This method identifies the top or second layer of natural leather through visual inspection and microscopic observation, identifies transfer film / lacquer film or regenerated leather through burning and water absorption methods, and identifies regenerated leather or artificial leather through heating and fading methods. The entire identification process is relatively complicated and cannot identify the animal species of natural leather.

[0005] Molecular biology technology uses DNA testing and other means to identify leather. Patent document No. CN104328186A discloses a DNA identification method for natural leather. This method uses fluorescent quantitative PCR to detect pig leather and can be used to identify pig leather samples processed by different processes. However, this method is expensive and complicated to operate, and can only be used to identify pig leather.

[0006] As a natural biological material, leather's identification features are primarily reflected in two aspects: first, surface characteristics, including grain pattern, pore morphology, and distribution. These characteristics are the primary basis for traditional identification methods, but they are significantly inadequate in practical application. Post-processing techniques such as coating and embossing, widely used in modern leather processing, can significantly alter or even completely obscure these surface features, significantly reducing the reliability of surface-based leather identification methods.

[0007] Another area of ​​focus is internal structural characteristics, particularly microscopic features such as the fiber structure and hair follicles visible in cross-section. These features are relatively stable and not easily affected by surface treatments. However, traditional methods for observing these internal features require preparing numerous sections or performing layer-by-layer polishing. This destructive sampling method is not only cumbersome, time-consuming, and labor-intensive, but more importantly, it irreversibly alters the original morphology and structure of the leather, affecting the accuracy of the test results.

[0008] Therefore, the development of a rapid, accurate, and non-destructive leather identification technology has become an urgent need in the industry. An ideal testing method should possess multiple advantages: it should be able to identify authenticity and leather type while maintaining sample integrity; it should be simple to operate, fast, and provide objective and quantifiable results; and most importantly, it should be applicable to leather samples processed by various techniques, overcoming the limitations of traditional methods in identifying complex samples. Summary of the Invention

[0009] In order to solve the above technical problems, the present invention provides a method for identifying pig leather, cow leather or sheep leather based on Micro-CT technology, which can deeply detect the internal three-dimensional structure of the leather without slicing, thereby realizing efficient and non-destructive identification of pig leather, cow leather or sheep leather.

[0010] The specific technical solutions adopted are as follows: A method for identifying pig leather, cow leather or sheep leather based on Micro-CT technology, comprising the following steps: (1) Perform Micro-CT scanning on the leather sample to obtain a three-dimensional image of the leather sample; (2) Use analysis software to virtually slice the three-dimensional image to obtain a longitudinal cross-sectional image of the internal structure of the leather sample; (3) Observe the penetration of hair follicles through the leather in the longitudinal cross-sectional image and measure the tilt angle between the hair follicles and the grain surface; (4) If the hair follicles penetrate the leather, it is determined to be pig leather; if the hair follicles do not penetrate the leather and the angle of inclination is 23°~30°, it is determined to be cow leather; if the hair follicles do not penetrate the leather and the angle of inclination is 13°~20°, it is determined to be sheep leather.

[0011] The present invention utilizes the non-destructive three-dimensional imaging capability of Micro-CT to quantitatively analyze the spatial morphological characteristics of the hair follicle structure in leather, and establishes a discrimination standard for pig leather, cow leather and sheep leather based on the inherent differences in the skin tissue structure of different species.

[0012] Preferably, the leather sample is cut into squares with a side length of 3-6 mm for Micro-CT scanning. This sample size range is compatible with the sample stage size of most Micro-CT equipment and, more importantly, ensures scan quality.

[0013] Preferably, in step (1), the Micro-CT scanning parameters are: source voltage 40-80 kV, power 5-10 W, objective lens 0.4X or 4X, exposure time 1-5 s, and number of projections 1601-3201. Within the selected parameter range, both scanning resolution and signal-to-noise ratio can be taken into account, meeting the imaging requirements of pig, cattle, and sheep leather samples.

[0014] Further preferably, in step (1), the Micro-CT scanning is set to be without filter and accurately centered.

[0015] Preferably, in step (1), after obtaining the three-dimensional image of the leather sample, the scanned data is reconstructed using Reconstructor software, and the quality of the three-dimensional image is improved by optimization, the feature recognition is enhanced, and the cross-sectional image is accurately analyzed after virtual slicing.

[0016] Preferably, in step (2), the process of virtually slicing the three-dimensional image is as follows: in the cross-sectional YZ view, the three-dimensional coordinate axis is positioned at a hair follicle on the cross section, the angle of the three-dimensional coordinate axis is adjusted so that the hair follicle is fully displayed in the XY view, and the longitudinal cross-sectional image is obtained by virtual slicing. By operating the above process, the hair follicle structure can be accurately located and the most representative cross-sectional image can be obtained.

[0017] Preferably, in step (2), the three-dimensional image is virtually sliced ​​using Dragonfly software.

[0018] Preferably, in step (3), the tilt angles between at least three hair follicles and the grain surface are measured and the average value is calculated. Multi-point measurement can improve data reliability and reduce errors caused by local variations.

[0019] The present invention also provides the use of hair follicle parameters in leather for identifying leather types. The hair follicle parameters include the extent of hair follicles penetrating the leather body and the angle between the hair follicles and the grain. The leather types to be identified are pig leather, cow leather, or sheep leather. Specifically, the hair follicle parameters in the leather are obtained using the aforementioned method for identifying pig leather, cow leather, or sheep leather based on Micro-CT technology, thereby identifying the pig leather, cow leather, or sheep leather.

[0020] Compared with the prior art, the present invention has the following beneficial effects: (1) The present invention uses Micro-CT to scan leather samples in all directions to obtain data images and uses three-dimensional analysis software to virtually slice the leather samples, eliminating the need for sample pre-processing such as embedding, slicing, and spraying. This not only simplifies the experimental process but, more importantly, maintains the original microstructural integrity of the sample, effectively solving the tissue deformation and artifact problems caused by physical slicing in traditional methods.

[0021] (2) The present invention utilizes 3D analysis software and a 3D reconstruction algorithm to iteratively optimize the original projection data to obtain a reconstructed stereo image. This eliminates visual interference such as sample drift, ray hardening, and artifacts during the scanning process. This improves the quality of the 3D image and enhances feature recognition, providing a reliable digital image foundation for subsequent microstructural analysis and enabling accurate analysis of scanned images of leather samples.

[0022] (3) The present invention achieves accurate identification of pig leather, cow leather or sheep leather by precisely measuring the tilt angle between the hair follicle and the grain surface and observing the penetration of the hair follicle. This technical solution not only improves the objectivity and repeatability of the identification results, but also provides technical support for the establishment of a standardized leather identification system. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 This is the measurement process of the tilt angle between the hair follicle and the grain surface in the present invention.

[0024] Figure 2 This is a longitudinal cross-sectional image of leather sample No. A in the example.

[0025] Figure 3 This is a longitudinal cross-sectional image of leather sample No. C in the example.

[0026] Figure 4 This is a longitudinal cross-sectional image of leather sample No. E in the example. DETAILED DESCRIPTION

[0027] In order to make the objects, features and advantages of the present invention more clearly understood, a detailed description is given below using specific embodiments. In the following description, many specific details are set forth to fully understand the present invention. However, the present invention can be implemented in many other ways than those described herein, and those skilled in the art can make similar improvements without violating the connotation of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below. The technical features in the various embodiments of the present invention can be combined accordingly without conflicting with each other.

[0028] Example Pig leather, cow leather or sheep leather identification method based on Micro-CT technology Leather samples were numbered A through L, with samples A through F having known leather species and samples G through L having unknown leather species. Leather samples A through L were cut into small square pieces measuring approximately 5 mm × 5 mm, a suitable size for easy fixation and imaging.

[0029] Use specialized superglue to securely adhere the leather sample to the pin tip, ensuring a secure bond and a flat surface to minimize imaging errors caused by tilt. Allow the secured leather sample to rest for a period of time until the glue is completely dry to prevent movement or shaking during subsequent manipulations.

[0030] Securely mount a pin on the Micro-CT sample stage and adjust the position so that the leather sample is within the optimal imaging range. Roughly center the leather sample. Set the objective to 4X, the source voltage to 60 kV, the power to 6.5 W, the exposure time to 1 s, the pixel mode to Bin 2, and no source filter.

[0031] Focus in continuous imaging mode. Once focused, adjust the distance between the sample, the source, and the detector to achieve a signal intensity of approximately 5000 and a transmittance greater than 70%, achieving a scanning resolution of approximately 3.4 μm. Based on the field of view (FOV), select 2401 projections and begin tomographic scanning.

[0032] Taking advantage of the differences in X-ray absorption among various parts of the leather, when the X-rays pass through the leather sample, the parts not absorbed by the sample are captured by the detector and converted into digital signals, obtaining a two-dimensional slice image. After a 360° full-scale scan, the original data of three orthogonal sections and a three-dimensional stereo image that can be freely segmented and called can be obtained.

[0033] The raw scanned data was imported into Reconstructor software for reconstruction and optimization. This optimization improved the 3D image quality and enhanced feature recognition, facilitating accurate analysis of cross-sectional images after virtual slicing. The reconstructed data was then imported into Dragonfly software. In the YZ view, the 3D coordinate axis was positioned on a hair follicle on the cross section. The 3D coordinate axis angle was adjusted to fully display the hair follicle in the XY view, and a longitudinal cross-sectional image was obtained through virtual slicing.

[0034] Observe the situation of hair follicles penetrating the leather body in the longitudinal section image. Figure 1 The measurement process shown measures the tilt angles between three or more hair follicles and the grain, calculates the average value, and ultimately determines the type of leather.

[0035] The test results of leather samples A to L are shown in Table 1 below, where the longitudinal section image of leather sample A is shown in Table 1. Figure 2 As shown, the longitudinal section image of leather sample C is as follows Figure 3 As shown, the longitudinal section image of leather sample E is as follows Figure 4 shown.

[0036] Table 1 Test results of leather samples A to L After testing and analysis, the leathers numbered A, B, I and K have hair follicles running through the leather body, and are judged to be pig leather. The longitudinal cross-section image of leather number A is shown in the figure below. Figure 2 As shown in the figure, it can be observed that the hair follicles run through the leather, and the inclination angle between the No. 1 hair follicle and the grain surface is 23.44°.

[0037] The hair follicles of leathers numbered C, D, G, and H do not penetrate the leather body. The average values ​​of the angles between the hair follicles and the grain are 26.85°, 26.78°, 26.38°, and 25.11°, respectively. They are within the range of 23° to 30°, and are therefore considered to be cowhide leather. The longitudinal cross-section image of leather number C is shown in the figure. Figure 3 As shown in the figure, it can be observed that the hair follicles do not penetrate the leather, and the inclination angle between the No. 1 hair follicle and the grain surface is 28.52°.

[0038] The hair follicles of leathers numbered E, F, J, and L do not penetrate the leather body. The average values ​​of the angles between the hair follicles and the grain are 18.53°, 18.81°, 18.86°, and 16.55°, respectively. They are within the range of 13° to 20°, and are therefore judged to be sheepskin. The longitudinal cross-section image of leather numbered E is shown in the figure below. Figure 4 As shown in the figure, it can be observed that the hair follicles do not penetrate the leather, and the inclination angle between the No. 1 hair follicle and the grain surface is 19.86°.

[0039] The leather samples numbered A-F were of known leather type. Table 1 shows that their identification results were consistent with the known leather types, demonstrating the reliability of the present method for identifying pig, cow, or sheep leather using Micro-CT technology. The leather types of leather samples numbered G-L were unknown, but the identification method of the present invention accurately and efficiently determined their leather types.

[0040] The embodiments described above provide a detailed description of the technical solutions of the present invention. It should be understood that the above are only specific embodiments of the present invention and are not intended to limit the present invention. Any modifications, supplements or similar substitutions made within the scope of the principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for identifying pig leather, cow leather or sheep leather based on Micro-CT technology, characterized in that: The steps include: (1) Perform Micro-CT scanning on the leather sample to obtain a three-dimensional image of the leather sample; (2) Use analysis software to virtually slice the three-dimensional image to obtain a longitudinal cross-sectional image of the internal structure of the leather sample; (3) Observe the penetration of hair follicles through the leather in the longitudinal cross-sectional image and measure the tilt angle between the hair follicles and the grain surface; (4) If the hair follicles penetrate the leather, it is determined to be pig leather; if the hair follicles do not penetrate the leather and the angle of inclination is 23°~30°, it is determined to be cow leather; if the hair follicles do not penetrate the leather and the angle of inclination is 13°~20°, it is determined to be sheep leather.

2. The method for identifying pig leather, cow leather or sheep leather based on Micro-CT technology according to claim 1, characterized in that: The leather samples were cut into squares with a side length of 3 to 6 mm for Micro-CT scanning.

3. The method for identifying pig leather, cow leather or sheep leather based on Micro-CT technology according to claim 1, characterized in that: In step (1), the setting parameters of Micro-CT scanning are: source voltage 40~80 kV, power 5~10 W, and exposure time 1~5 s.

4. The method for identifying pig leather, cow leather or sheep leather based on Micro-CT technology according to claim 1, characterized in that: In step (1), after obtaining the three-dimensional image of the leather sample, the scanned data is reconstructed into three dimensions using Reconstructor software.

5. The method for identifying pig leather, cow leather or sheep leather based on Micro-CT technology according to claim 1, characterized in that: In step (2), the process of virtually slicing the three-dimensional image is as follows: in the YZ view, the three-dimensional coordinate axis is positioned at a hair follicle on the cross section, the angle of the three-dimensional coordinate axis is adjusted so that the hair follicle is fully displayed in the XY view, and the longitudinal section image is obtained by virtual slicing.

6. The method for identifying pig leather, cow leather or sheep leather based on Micro-CT technology according to claim 1, characterized in that: In step (2), the three-dimensional image is virtually sliced ​​using Dragonfly software.

7. The method for identifying pig leather, cow leather or sheep leather based on Micro-CT technology according to claim 1, characterized in that: In step (3), the tilt angles between at least three hair follicles and the grain surface are measured and the average value is calculated.

8. Application of hair follicle parameters in leather in identifying leather types, characterized in that: The follicle parameters include the condition of the follicles penetrating the leather body and the tilt angle between the follicles and the grain. The leather to be identified is pig leather, cow leather or sheep leather.

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