A method and system for detecting the porosity and pore distribution of cigarettes.

Abstract

This invention discloses a method and system for detecting the porosity and pore distribution of cigarettes. The method includes: equilibrating a cigarette sample under relative humidity W and temperature T; segmenting the equilibrated cigarette sample into sections according to a preset method, performing nuclear magnetic resonance (NMR) scanning to obtain NMR images; determining a segmentation threshold based on the grayscale image of the NMR image; performing binarization processing on the image to separate the foreground and background based on the segmentation threshold to obtain a binary image that distinguishes air pores from moisture-containing cigarette tobacco; obtaining the pore distribution of the cigarette based on the binary image and calculating the cigarette porosity. This method enables the analysis and evaluation of the cigarette porosity distribution, improving the accuracy of porosity measurement.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of tobacco and tobacco product detection, and relates to a detection method and system for cigarette porosity and pore distribution, in particular to a nuclear magnetic imaging detection method for obtaining cigarette pore distribution. BACKGROUND

[0002] The internal void structure and tobacco filler of a cigarette have an important influence on the quality of the cigarette. The main goal of the void structure of the tobacco filler of the cigarette is to test the quality of the cigarette and improve the smoking comfort and sensory quality of the cigarette. The more uniform the porosity distribution of the cigarette is, the better the uniformity of the filler is, the higher the consistency of the density is, and the more stable the sensory quality is. The porosity of the cigarette is different from the porosity in the fields of medicine and materials, and the porosity of the cigarette only includes the voids between the tobacco fillers, but does not include the pores of the tobacco fillers. The porosity in the fields of medicine and materials generally refers to the pores inside a material.

[0003] In the prior art, CN113702258A proposes to use tomography technology to nondestructively test a cigarette, to obtain the variance and variation of the porosity distribution of the cigarette sample along the axial direction by reconstructing a three-dimensional model of the cigarette sample. However, since the tomography technology is a physical parameter attenuation imaging, it cannot reflect the heterogeneity of the internal structure, that is, it cannot reflect the distribution of water and other chemical components in addition to the internal structure.

[0004] At present, there is still a lack of effective methods to simultaneously detect the distribution of the porosity and the water distribution of the cigarette in any direction. SUMMARY

[0005] Objective: In order to overcome the deficiencies in the prior art, the application provides a detection method and system for the porosity and pore distribution of a cigarette, which realizes the analysis and evaluation of the porosity distribution of the cigarette through the chemical component distribution of the cigarette, and improves the accuracy of the porosity measurement.

[0006] In recent years, nuclear magnetic resonance imaging technology has been widely used in the detection of water distribution state and oil content in the field of food, and mainly determines the length of the transverse and longitudinal relaxation time of hydrogen nuclei in a substance under the action of a magnetic field and a radio frequency signal, to study the distribution and migration of water in the material and other properties related thereto. As a widely used method, nuclear magnetic resonance imaging technology and nuclear magnetic resonance relaxation can provide information such as water content and micro-pore structure inside the tissue. Through related research work, the nuclear magnetic resonance relaxation measurement results can also be associated with the permeability parameters through some empirical formulas and pore network models.

[0007] From the above concept, the calculation formula of the porosity of the cigarette can be obtained as follows:

[0008]

[0009] In the formula, V0 represents the total volume of the air gap between the tobacco shreds, and V represents the volume of the cigarette.

[0010] Technical solution: To solve the above technical problems, the technical solution adopted by the present application is:

[0011] In the first aspect, the present application provides a method for detecting the porosity and pore distribution of a cigarette, comprising:

[0012] Step (1) : moisture equilibration of the cigarette sample at a relative humidity W and a temperature T;

[0013] Step (2) : segmented cutting of the moisture equilibrated cigarette sample according to a preset mode, nuclear magnetic scanning, and obtaining a nuclear magnetic resonance image;

[0014] Step (3) : determination of a segmentation threshold value according to the gray image of the nuclear magnetic resonance image, foreground and background separation of the image according to the segmentation threshold value, and binary image processing to obtain a binary image that distinguishes the air pores from the water-containing cigarette tobacco shreds;

[0015] Step (4) : obtaining the pore distribution of the cigarette according to the binary image, and calculating the porosity of the cigarette.

[0016] In some embodiments, in step (1), the relative humidity W is 60±2%, and the temperature T is 22±1℃.

[0017] In some embodiments, in step (1), the time for moisture equilibration of the cigarette sample is 18-48h, preferably 24h.

[0018] In some embodiments, in step (2), the nuclear magnetic scanning is performed by at least one of the following methods:

[0019] (2a) : nuclear magnetic scanning by using a spin echo imaging method to image a first type of substance with high molecular mobility, and determining the distribution of the first type of substance in the cigarette sample, wherein the first type of substance includes moisture, polyhydric alcohol, sugar, and hydrocarbon wax;

[0020] (2b) : nuclear magnetic scanning by using a single-point imaging method to image a second type of substance that is relatively hard in the cigarette, wherein the second type of substance includes tobacco cell wall polysaccharide and cellulose acetate fibers.

[0021] Further, in some embodiments, the working frequency for nuclear magnetic scanning by using the spin echo imaging method is 21MHz.

[0022] Further, in some embodiments, the working frequency for nuclear magnetic scanning by using the single-point imaging method is 100-600MHz, and the resolution is 100-1000μm.

[0023] In some embodiments, in step (3), determining the segmentation threshold according to the gray image of the nuclear magnetic resonance image comprises:

[0024] The gray image is 8-bit, and the gray range is 0-255;

[0025] The IsoDate algorithm is used for segmentation, and the segmentation threshold is determined according to the actual thickness of the parallel sample cigarette paper and the pixel ratio.

[0026] In some embodiments, in step (4), calculating the cigarette porosity comprises:

[0027]

[0028] Wherein, δ0 is the cigarette porosity, n is the total number of nuclear magnetic scanning sections and is not less than 10, K is the total number of pixels in the measurement area, K n is the number of pixels of the porosity in the imaging area for each measurement.

[0029] In some embodiments, in step (2), segmenting the water balance cigarette sample according to the preset mode comprises:

[0030] The cigarette is segmented in multiple different segmentation modes, and is segmented in parallel equidistant or central rotational symmetry according to an arbitrary angle θ inclined to the radial direction of the cigarette, wherein the angle θ is 0°-90°.

[0031] In some preferred embodiments, the angle θ is 90°, and the cigarette is segmented in axial equidistant, and the segmentation interval is 1mm;

[0032] In another preferred embodiment, the angle θ is 0°, and the segmentation section is radially rotationally symmetrical through the center axis of the cigarette, and the segmentation interval angle is 30°.

[0033] In a second aspect, the present application provides a detection system for cigarette porosity and pore distribution, comprising:

[0034] A water balance module configured to balance the moisture of the cigarette sample at a relative humidity W and a temperature T;

[0035] A segmentation nuclear magnetic scanning module configured to segment and cut the water balance cigarette sample according to a preset mode, perform nuclear magnetic scanning, and obtain a nuclear magnetic resonance image;

[0036] A binary processing module configured to determine a segmentation threshold according to a gray image of the nuclear magnetic resonance image, perform binary processing of the image according to the segmentation threshold to separate the foreground and background, and obtain a binary image separating the air pores and the water-containing cigarette tobacco;

[0037] A porosity calculation module is configured to obtain the porosity distribution of the cigarette according to the binary image and calculate the porosity of the cigarette.

[0038] In a third aspect, the application provides a storage medium having stored thereon a computer program which, when executed by a processor, implements the steps of the method of the first aspect.

[0039] Beneficial effects: The cigarette porosity and porosity distribution detection method and system provided by the application can obtain the porosity distribution of a cigarette sample in any direction by performing nuclear magnetic scanning on the cigarette sample and performing model calculation, with n being the number of nuclear magnetic sections taken. The application uses nuclear magnetic resonance technology to evaluate the porosity distribution of the cigarette, which is simple to operate, time-saving, reduces research and development costs, and improves work efficiency. Moreover, the application allows selective analysis of different molecular mobility phases, and realizes non-destructive analysis.

[0040] The application uses nuclear magnetic resonance imaging technology to determine the porosity structure distribution of the cigarette, and can also detect the porosity of segmented cigarettes. Nuclear magnetic imaging can be used to process batches of tobacco and cigarettes. By combining spin echo imaging with relaxation measurement and data fitting, one-dimensional, two-dimensional and three-dimensional mapping can be constructed to further distinguish different chemical composition structures with distinguishable resonance conditions.

[0041] The axial and radial porosity and porosity distribution data of the cigarette obtained by the application can guide the production process and quality inspection, provide data support for improving the filling uniformity of the cigarette, and realize non-destructive quantitative analysis compared with the traditional density method, and can better reflect the distribution and movement of chemical components compared with the tomography technology. The application uses nuclear magnetic resonance technology to evaluate the performance of the cigarette, which is simple to operate, time-saving, and can quickly and effectively achieve the purpose of porosity structure evaluation and detection. Moreover, the application has the advantage of non-destructive testing, avoids waste of raw materials, reduces material loss during development, reduces research and development costs, and improves work efficiency.

[0042] By related calculation and cutting segmentation, one-dimensional, two-dimensional and three-dimensional imaging analysis of the chemical component distribution and flow change of different parts of the cigarette or tobacco product can be performed. When the number of segments or sections is reasonable, the porosity structure and porosity distribution can be accurately and efficiently researched and detected. The method can also realize porosity size statistics and related quantitative analysis of the porosity distribution of the directional section, so as to improve the understanding of the accumulation and distribution of the tobacco in the cigarette. BRIEF DESCRIPTION OF DRAWINGS

[0043] Figure 1 The flow chart of the cigarette porosity distribution detection method of the embodiment of the application is shown in the figure.

[0044] Figure 2 The axial segmentation schematic diagram of the cigarette sample in the embodiment of the application is shown in the figure.

[0045] Figure 3 A schematic diagram for radial segmentation of a cigarette sample in an embodiment of the present application;

[0046] Figure 4 A schematic diagram for IsoDate algorithm for binarization of a nuclear magnetic scanning image. DETAILED DESCRIPTION

[0047] The present application will be further described below in conjunction with the accompanying drawings and embodiments. The following embodiments are only used to more clearly illustrate the technical solutions of the present application, and cannot be used to limit the protection scope of the present application.

[0048] In the description of the present application, if the meaning of several is more than one, the meaning of multiple is more than two, greater than, less than, more than, etc. are understood as not including the number, above, below, within, etc. are understood as including the number. If it is described as first, second, it is only used for the purpose of distinguishing technical features, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of indicated technical features or the sequence of indicated technical features.

[0049] In the description of the present application, the description of the reference terms "one embodiment", "some embodiments", "exemplary embodiment", "example", "specific example", or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present application. In the present specification, the exemplary description of the above terms does not necessarily refer to the same embodiment or example. Moreover, the described specific features, structures, materials or characteristics can be combined in any one or more embodiments or examples in a suitable manner.

[0050] A detection method for porosity and pore distribution of a cigarette, comprising:

[0051] Step (1) moisture equilibration of a cigarette sample at relative humidity W and temperature T;

[0052] Step (2) segmented cutting of the moisture equilibrated cigarette sample according to a preset mode, nuclear magnetic scanning, and obtaining a nuclear magnetic resonance image;

[0053] Step (3) determining a segmentation threshold value according to a gray scale image of the nuclear magnetic resonance image, binarization processing of foreground and background separation of the image according to the segmentation threshold value, and obtaining a binary image separating air pores from water-containing cigarette tobacco;

[0054] Step (4) obtaining the pore distribution of the cigarette according to the binary image, and calculating the porosity of the cigarette.

[0055] Embodiment 1

[0056] The cigarette pore distribution detection method of the embodiment, a flow chart is shown in Figure 1 , comprising the following steps:

[0057] 1) The cigarette sample or part of the cigarette is balanced under the environmental conditions;

[0058] For material pretreatment under certain environmental conditions, moisture balance is selected for 24 hours under the condition of relative humidity of 60% and environmental temperature of 22°C. The M and T values can be determined and adjusted according to actual needs and equipment conditions.

[0059] (2) Perform nuclear magnetic scanning to obtain a nuclear magnetic resonance image;

[0060] According to the different attenuation of the energy released by the nuclear magnetic equipment in different structural environments inside the material, the emitted electromagnetic waves are detected through an external gradient magnetic field, so that the position and type of the atomic nucleus constituting the object can be known, and a structural image inside the object can be drawn accordingly.

[0061] For the nuclear magnetic imaging direction, the cutting angle θ is determined to be 90° as shown in Figure 2 , and the cigarette is cut according to the axial equidistance, with a cutting interval of 1 mm;

[0062] In order to eliminate the influence of the pores of the tobacco itself, it is necessary to determine a suitable scanning imaging resolution, so that the resolution is within the range of the pores of the tobacco itself and the gap between the tobaccos. Generally, the thickness of the tobacco is 0.1 mm, the width is 1 mm, and the internal pore structure is between 10 μm and 100 μm;

[0063] The nuclear magnetic resonance imaging is performed at a working frequency of 100 MHz; and the nuclear magnetic resonance imaging resolution is 300 μm.

[0064] (3) Spin echo imaging analysis is used to obtain the water distribution and relaxation;

[0065] Imaging of substances with high molecular mobility can determine the distribution and diffusion migration of water, active wax and other substances in the cigarette. The nuclear magnetic frequency is 21 MHz.

[0066] (4) Single-point imaging method is used to analyze the harder components in the cigarette;

[0067] According to the required image of the distribution of the hard fiber cell wall structure of the tobacco, the single-point imaging method is used to analyze the harder components in the cigarette according to the requirements of steps (3) and (4), so as to realize the imaging of tobacco cell wall polysaccharide and cellulose acetate fiber.

[0068] (5) According to as shown in Figure 1The process handles the nuclear magnetic image, determines the gray scale image as 8 bits, and the gray scale range is 0-255; the IsoData algorithm is used for processing, and the segmentation threshold is determined according to the actual thickness of the parallel sample cigarette paper and the pixel ratio;

[0069] The IsoData algorithm, i.e. the iterative self-organizing data analysis algorithm, has a process as shown in the accompanying Figure 4 figure. The human-computer interaction link is introduced by setting initial parameters, and the merging and splitting mechanism is used. When the distance between the cluster centers of two classes is less than a certain threshold, they are merged into one class. When the standard deviation of a class is greater than a certain threshold or the number of samples thereof exceeds a certain threshold, it is divided into two classes. When the number of samples in a class is less than a certain threshold, it needs to be cancelled. In this way, according to the initial cluster center and the set number of classes and other parameters, the pores and cigarette fillers can be finally distinguished.

[0070] The segmentation threshold can be determined according to the cigarette overwrap paper thickness corresponding to the same parallel sample. After the image is uniformly processed in gray scale, the number of pixel points in the picture corresponding to the same thickness of cigarette paper is the same, so the segmentation threshold can be determined according to the pixel points corresponding to the cigarette paper part before and after the binarization processing. Thus, the binarized image under the uniform processing condition is obtained.

[0071] (6) The porosity is calculated, and the optimal cutting method corresponding to the cigarette variety / lot is obtained according to the increased n value;

[0072] According to the obtained binarized image, the pixel number ratio relationship of the filling part and the whole is identified and calculated, the porosity of different segmentation sections is determined, and the pore size and distribution are counted.

[0073]

[0074] Wherein, n is the total number of nuclear magnetic scanning cuts and is not less than 10, K is the total number of pixels in the measurement area, K n is the number of pixels of the pore in the imaging area measured each time.

[0075] The n value is determined to make the porosity distribution error stable at ±1%; the average value of the first n-1 times is taken for error calculation.

[0076] Further, in the research process, it also includes: (7) each time, the same direction segmentation method is used to divide the cigarette along the axial direction or to divide the same angle radially, and the porosity obtained by each segmentation method is calculated; the pore distribution and porosity after changing the different cutting angles θ are compared and analyzed.

[0077] (8) The whole cigarette or a certain part is segmented and calculated;

[0078] Under the premise of the same segmentation method and processing method in the previous steps (1) to (7), the relevant parameter calculation and statistical analysis of different parts of the cigarette are carried out. When θ is 90°, the cut section number is 2, 4, 8, 16, 32 and 64, and the uniform cigarette section can be obtained. The relevant porosity test and uniformity test analysis can be carried out on any section.

[0079] Example 2

[0080] The cigarette porosity detection method of the present embodiment is described as follows, and the other steps not introduced are the same as in Example 1.

[0081] (1) The cigarette sample or part of the cigarette is balanced under the environmental conditions;

[0082] For the pretreatment of the material under certain environmental conditions, the moisture balance is carried out for 24 hours under the condition of relative humidity of 60% and environmental temperature of 22°C.

[0083] (2) Nuclear magnetic scanning is carried out to obtain the nuclear magnetic resonance image;

[0084] For the nuclear magnetic imaging direction, the cutting angle θ is determined as 0°, and the cigarette is divided according to the radial rotational symmetry with a division interval angle of 30°, as shown in Figure 3

[0085] The nuclear magnetic resonance imaging is carried out at a working frequency of 200MHz; the nuclear magnetic resonance imaging resolution is 300μm.

[0086] (3) Spin echo imaging analysis is used to obtain the water distribution and relaxation;

[0087] Imaging of substances with high molecular mobility can determine the distribution and diffusion migration of water, active wax and other substances in the cigarette. The nuclear magnetic frequency is 21MHz.

[0088] (4) Single-point imaging method is used to analyze the harder components in the cigarette;

[0089] According to the required image of the hard fiber cell wall structure distribution of the tobacco, the single-point imaging method is used to analyze the harder components in the cigarette according to the requirements of steps (3) and (4), and the imaging of tobacco cell wall polysaccharide and cellulose acetate fiber is realized.

[0090] (5) The nuclear magnetic image is processed according to the flow Figure 1 The gray image is determined as 8 bits and the gray scale range is 0-255; the IsoDate algorithm is used for processing, and the segmentation threshold is determined according to the actual thickness of the parallel sample cigarette paper and the pixel ratio.

[0091] ​(6) Obtain the porosity, and calculate and obtain the optimal cutting mode of the corresponding cigarette variety / batch according to the increase in the n value.

[0092] In some embodiments, it can also include: (7) divide the cigarette along the axial direction or radially at the same angle by using the same direction of division each time, and obtain the porosity of each division mode.

[0093] (8) Calculate the division and the uniformity of the tobacco distribution inside the cigarette.

[0094] Embodiment 3

[0095] In a second aspect, based on the above-mentioned embodiments 1 and 2, the present embodiment provides a detection system for the porosity and porosity distribution of a cigarette, comprising:

[0096] A moisture balance module configured to balance the moisture of the cigarette sample at a relative humidity W and a temperature T;

[0097] A segmentation nuclear magnetic scanning module configured to segment and cut the cigarette sample after moisture balance in a preset mode, perform nuclear magnetic scanning, and obtain a nuclear magnetic resonance image;

[0098] A binary processing module configured to determine a segmentation threshold value according to a gray image of the nuclear magnetic resonance image, perform binary processing of the image according to the segmentation threshold value to separate the foreground and background, and obtain a binary image that distinguishes the air porosity from the water-containing cigarette tobacco;

[0099] A porosity calculation module configured to obtain the porosity distribution of the cigarette according to the binary image, and calculate the porosity of the cigarette.

[0100] Embodiment 4

[0101] In a third aspect, the present embodiment provides a storage medium having a computer program stored thereon, wherein the computer program is executed by a processor to implement the steps of the method of embodiments 1 or 2.

[0102] Those skilled in the art will appreciate that the embodiments of the present application can be provided as a method, a system, or a computer program product. Therefore, the present application can be in the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware aspects. Moreover, the present application can be in the form of a computer program product implemented on one or more computer usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer usable program code.

[0103] The computer program instructions can also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer-implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions specified in the flowchart block or blocks. Figure 1 one or more flow or blocks. Figure 1 one or more flow or blocks.

[0104] These computer program instructions can also be stored in a computer readable memory that can direct a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer readable memory produce an article of manufacture including instructions which implement the function specified in the flowchart block or blocks. Figure 1 one or more flow or blocks. Figure 1 one or more flow or blocks.

[0105] The computer program instructions can also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer-implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions specified in the flowchart block or blocks. Figure 1 one or more flow or blocks. ​ one or more flow or blocks.

[0106] The above only is the preferred embodiment of the present application, it should be pointed out that for the ordinary skilled in the art, without departing from the principles of the present application, can also make a number of improvements and refinements, these improvements and refinements should also be considered as the protection scope of the present application.

Claims

1. A method for detecting the porosity and pore distribution of a cigarette, characterized by, The method comprises the following steps: Step (1) moisture equilibration of the cigarette sample at a relative humidity W and a temperature T; Step (2) segmentation cutting of the moisture equilibrated cigarette sample in a preset manner, nuclear magnetic scanning, and obtaining a nuclear magnetic resonance image; wherein the segmentation cutting of the moisture equilibrated cigarette sample in the preset manner comprises: segmenting the cigarette in a plurality of different segmentation manners, and performing parallel equidistant segmentation or central rotational symmetry segmentation at an arbitrary angle θ inclined to the radial direction of the cigarette, wherein the angle θ is 0°-90°; the nuclear magnetic scanning comprises: (2a) nuclear magnetic scanning by using a spin echo imaging method to image a first type of substance with high molecular mobility, and determining the distribution of the first type of substance in the cigarette sample, wherein the first type of substance comprises moisture, polyhydric alcohol, sugar, and hydrocarbon wax; (2b) nuclear magnetic scanning by using a single-point imaging method to image a second type of substance which is relatively hard in the cigarette, wherein the second type of substance comprises tobacco cell wall polysaccharide and cellulose acetate fiber; Step (3) determining a segmentation threshold value according to a gray-scale image of the nuclear magnetic resonance image, performing binaryzation processing of foreground and background separation of the image according to the segmentation threshold value, and obtaining a binary image for distinguishing air pores from water-containing cigarette tobacco; Step (4) obtaining a pore distribution of the cigarette according to the binary image, and calculating a cigarette porosity; wherein the calculation of the cigarette porosity comprises: wherein δ0 is the cigarette porosity, n is the total number of cross sections scanned by NMR and is not less than 10, K is the total number of pixels of the measurement area, K n is the number of pixels of the porosity of the imaged area for each measurement.

2. The method of claim 1, wherein, In step (1), the relative humidity W is 60±2%, and the temperature T is 22±1℃.

3. The method of claim 1, wherein the cigarette porosity and pore distribution is determined by measuring the change in the capacitance of the sensor before and after the cigarette is inserted into the sensor. In step (1), the moisture equilibration time of the cigarette sample is 18-48h.

4. The method of claim 1, wherein the cigarette porosity and pore distribution is determined by measuring the change in the capacitance of the sensor before and after the cigarette is inserted into the sensor. The working frequency of the nuclear magnetic scanning by using the spin echo imaging method is 21MHz; The working frequency of the nuclear magnetic scanning by using the single-point imaging method is 100MHz-600MHz, and the resolution is 100-1000μm.

5. The method of claim 1, wherein the cigarette porosity and pore distribution is determined by measuring the change in the capacitance of the sensor before and after the cigarette is inserted into the sensor. In step (3), the determination of the segmentation threshold value according to the gray-scale image of the nuclear magnetic resonance image comprises: The gray-scale image is 8-bit, and the gray-scale range is 0-255; The IsoDate algorithm is used for segmentation, and the segmentation threshold value is determined according to the actual thickness of the parallel sample cigarette paper and the pixel ratio.

6. The method of claim 1, wherein the cigarette porosity and pore distribution is determined by measuring the change in the capacitance of the sensor before and after the cigarette is inserted into the sensor. The angle θ is 90°, the cigarette is segmented in an axial equidistant manner, and the segmentation interval is 1mm; And / or, the angle θ is 0°, the segmentation cross section is radially rotationally symmetrical about the central axis of the cigarette, and the segmentation interval angle is 30°.

7. A system for detecting the porosity and pore distribution of a cigarette, characterized by The method comprises the following steps: A moisture equilibration module is configured to perform moisture equilibration of a cigarette sample at a relative humidity W and a temperature T; The segmentation nuclear magnetic scanning module is configured to segment and cut the moisture-balanced cigarette sample in a preset manner, perform nuclear magnetic scanning, and obtain a nuclear magnetic resonance image; wherein the segmenting and cutting the moisture-balanced cigarette sample in a preset manner comprises segmenting the cigarette in multiple different segmentation manners, and performing parallel equidistant segmentation or central rotational symmetry segmentation at an arbitrary angle θ inclined to the radial direction of the cigarette, wherein the angle θ is 0°-90°; the nuclear magnetic scanning comprises: (2a) performing nuclear magnetic scanning by using a spin echo imaging method to image a first type of substance with high molecular mobility, and determining the distribution of the first type of substance in the cigarette sample, wherein the first type of substance includes moisture, polyhydric alcohol, sugar, and hydrocarbon wax; and (2b) performing nuclear magnetic scanning by using a single-point imaging method to image a second type of substance which is relatively hard in the cigarette, wherein the second type of substance includes tobacco cell wall polysaccharide and cellulose acetate fibers; The binarization processing module is configured to determine a segmentation threshold value according to a gray-scale image of the nuclear magnetic resonance image, perform foreground and background separation binarization processing on the image according to the segmentation threshold value, and obtain a binary image for distinguishing air pores from water-containing cigarette tobacco; The porosity calculation module is configured to obtain a pore distribution of the cigarette according to the binary image, and calculate a porosity of the cigarette; wherein the calculation of the porosity of the cigarette comprises: wherein δ0 is the cigarette porosity, n is the total number of cross sections scanned by NMR and is not less than 10, K is the total number of pixels of the measurement area, K n is the number of pixels of the porosity of the imaged area for each measurement.

8. A storage medium having stored thereon a computer program, characterized in that The computer program is executed by the processor to realize the steps of the method of any one of claims 1 to 6.

Images