Calculation method and measurement method for fibrillation index of plant fiber

Abstract

The invention provides a calculation method and a measurement method of a plant fiber fibrillation index, and the calculation method is used for calculating the plant fiber fibrillation index based on the area and length of a fibril and a main fiber through the operations of binarization color inversion, skeletonization, plant fiber main body / fibril segmentation and identification and the like. And accurate characterization of the fibrillation degree of the fiber in the high-magnification image is realized. According to the method for measuring the fibrillation index of the plant fibers, by means of a traditional optical digital microscope and a designed observation pool and in combination with a fibrillation calculation method, rapid and continuous shooting of images and large sample statistics of fibrillation fibers are achieved; the problems of tedious and time-consuming identification and quantification caused by a large amount of manual processing, few statistical samples, inaccurate manual subjectivity and the like are solved.

Description

Technical Field

[0001] The invention relates to a method for calculating and measuring a plant fiber filamentation index, and in particular to a method for calculating and measuring a plant fiber filamentation index based on image analysis. Background Art

[0002] Cellulose fiber is a natural or artificial fiber widely used in papermaking, textile, medicine and other fields. In the industrial production process, in order to improve the interweaving and bonding ability between cellulose fibers, the outer surface is made to produce "fluffing" through mechanical actions such as rubbing, squeezing, and tearing, which is called fibrillation in the industry. However, the characterization of the fibrillation degree of cellulose fibers is extremely challenging. At present, the degree of fibrillation is mainly judged qualitatively based on microscopic imaging. Although the concept of plant fiber fibrillation index is introduced in the literature, for example, it is characterized based on the total length of the filaments divided by the fiber length. Usually, this quantification work is done by manually processing each plant fiber image using image software, identifying the fibers and fibrils in the image and calculating the corresponding lengths. Since a large number of plant fiber images need to be processed for the results to be statistically significant, this manual processing is huge and time-consuming. Summary of the invention

[0003] The purpose of the present invention is to address the deficiencies of the above-mentioned prior art and propose a method for calculating and measuring the plant fiber filament broom index based on image analysis and processing. The calculation method calculates the plant fiber filament broom index based on the fiber segment through operations such as binarization, skeletonization, plant fiber body / filament segmentation and identification. The measurement method uses a traditional optical digital microscope and a designed observation pool, and is combined with a method for calculating filament broom to achieve rapid and continuous image shooting and large sample statistics of filament broom fibers, solving the problems of cumbersome and time-consuming identification and quantification caused by a large amount of manual processing, small number of statistical samples, and inaccuracy caused by human subjectivity.

[0004] The present invention is achieved by at least one of the following technical solutions:

[0005] A method for calculating and measuring the fiber fibrillation index of plant fibers comprises the following steps:

[0006] (1) The image of the plant fiber is obtained by taking pictures with an optical digital microscope;

[0007] (2) converting the fiber image into a grayscale image, and performing binarization and color inversion in sequence to obtain a binarized color inversion image;

[0008] (3) based on a graphical algorithm, the fibers that are not at the edge of the binary inverted image are numbered in sequence to obtain a numbering matrix;

[0009] (4) For a fiber with a certain serial number, a fiber template binary image with a size of [1: Xmax-Xmin+1, 1: Ymax-Ymin+1] is established based on the minimum value Xmin and maximum value Xmax of the first dimension of the fiber coordinates and the minimum value Ymin and maximum value Ymax of the second dimension. The fiber is mapped from the binary inverted image to the fiber template binary image, so that the value of the fiber coordinate in the fiber template binary image is 1, and the value of the non-fiber coordinate is 0;

[0010] (5) skeletonizing the fiber template binary image to obtain a fiber skeleton image;

[0011] (6) For the fiber skeleton diagram, the coordinates of the bifurcation points are determined based on the points at the intersections formed by three or more lines. With the bifurcation point as the center, the eight adjacent coordinates are assigned a value of 0 to segment the fiber skeleton diagram. The fiber skeleton diagram is numbered as in step (3), and a set of skeleton segment coordinates corresponding to each number is obtained.

[0012] (7) For the skeleton with the same number in the fiber skeleton diagram, perform graphical expansion. Each expansion will increase the distance by one pixel unit. The fiber coordinate point whose distance from the skeleton with the same number is equal to the expansion distance is marked as the fiber segment image point. When the number of newly added fiber segment image points after expansion is less than the critical number of fiber segment image points, stop the expansion, record the coordinates of the fiber segment image points and the skeleton coordinates during this process, and save them in the fiber segment coordinate set with the same number as the skeleton segment coordinate set;

[0013] (8) traversing each fiber segment coordinate set, taking the number of coordinates in the fiber segment coordinate set as the fiber segment area, taking the number of coordinates in the corresponding skeleton segment coordinate set as the fiber segment length, and calculating the fiber segment width by dividing the fiber segment area by the fiber segment length, and establishing a fiber segment set, wherein each fiber segment includes information on the mapping of the fiber segment area, the fiber segment length, the fiber segment width, and the skeleton segment coordinate set;

[0014] (9) The fiber segment with the maximum fiber width is taken as the main fiber, and the fiber segment set and the skeleton segment coordinate set mapped to it are saved in the main fiber set and the main fiber skeleton coordinate set respectively. The fiber segment set with a fiber width greater than the critical fiber width is traversed. When the distance between the two end point coordinates of the main fiber skeleton coordinate set and the two end point coordinates of the traversed skeleton segment coordinate set is less than the critical distance, all the coordinates of the skeleton segment are merged into the main fiber skeleton set, and the corresponding fiber segment is merged into the main fiber set at the same time;

[0015] (10) Repeat step (9) until the main fiber set cannot be updated, and then the main fiber set in the fiber segment set is deleted, and the remaining fiber segment set is recorded as the fiber set;

[0016] (11) Based on the main fiber set and the filament set, the total filament length, average filament length, main fiber length, total filament area and main fiber area were calculated. The fibrilization index was characterized by four different methods: the first was the total filament length / main fiber length, the second was the total filament area / main fiber area, the third was the average filament length / main fiber length, and the fourth was the average filament area / main fiber area.

[0017] (12) repeating steps (4) to (11) to calculate the fiber splitting index of all fibers in the fiber image;

[0018] The number of critical fiber segment image points described in step (7) is (1.1-1.3)×fiber skeleton length.

[0019] The critical fiber width described in step (9) is (0.5-0.8)×maximum fiber width, and the critical distance is 3-8 pixel distances.

[0020] The measurement method based on the above-mentioned calculation method of the fiber fibrillation index is as follows: place the detection cell on the stage of the optical digital microscope, one end of the detection cell is connected to the beaker, and the other end is connected to the peristaltic pump, the hose at the other end of the peristaltic pump is placed in the beaker, and the beaker is placed on a magnetic stirrer; add 0.0005%-0.01% concentration of fiber suspension to the beaker, turn on the magnetic stirrer, and after stabilization, turn on the peristaltic pump. When the fiber suspension flows back to the beaker, the peristaltic pump is set to run for 1 second and pause for 1 second in a cycle, and the fiber image is taken during the pause.

[0021] The detection pool is a rectangular parallelepiped, with an observation surface and a light-transmitting surface facing each other and both being planes. A capillary tube with a diameter of 0.1-0.2 mm is fixed in the middle of the detection pool, and both ends of the capillary tube are connected to water inlet and outlet pipes.

[0022] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0023] (1) Based on the image recognition method, the main fibers and filaments can be automatically identified and counted, avoiding the subjectivity and time-consuming problems of manual counting.

[0024] (2) Four methods were used to calculate the fiber fibrillation index of plant fibers, realizing the multi-angle definition and characterization of the degree of fiber fibrillation.

[0025] (3) The present invention uses a traditional optical digital microscope and a designed detection cell to achieve high-precision, rapid and low-cost fiber image capture, and at the same time combines an image-based method for calculating the fiber splitting index to achieve statistics on the number of multiple samples of fiber splitting. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1Schematic diagram of plant fiber image and image processing in different steps of the present invention DETAILED DESCRIPTION

[0027] The present invention is further described in detail below in conjunction with embodiments and drawings, but the embodiments of the present invention are not limited thereto.

[0028] like Figure 1 The invention discloses a method for calculating and measuring the fiber fibrillation index of plant fibers, comprising the following steps:

[0029] (1) The images of plant fibers were obtained by optical digital microscope (see Figure 1 a);

[0030] (2) The fiber image was converted into a grayscale image using Matlab software, and then binarized and inverted to obtain a binary inverted image (see Figure 1 b), where the fibers are white, with a value of 1, and the background is black, with a value of 0;

[0031] (3) based on the graphical algorithm, the fibers that are not at the edge of the binary inverted image are numbered in sequence to obtain a numbering matrix, which is the same size as the coordinate matrix of the binary inverted image, and the coordinate numbering values ​​of the same fiber are the same, while the coordinate numbering values ​​of different fibers are different;

[0032] (4) For a fiber with a certain serial number, a fiber template binary image with a size of [1: Xmax-Xmin+1, 1: Ymax-Ymin+1] is established based on the minimum value Xmin and maximum value Xmax of the first dimension of the fiber coordinates and the minimum value Ymin and maximum value Ymax of the second dimension. The fiber is mapped from the binary inverted image to the fiber template binary image, so that the value of the fiber coordinate in the fiber template binary image is 1, and the value of the non-fiber coordinate is 0;

[0033] (5) Skeletonization is performed on the fiber template binary image to obtain the fiber skeleton image (see Figure 1 c);

[0034] (6) For the fiber skeleton diagram, the coordinates of the bifurcation points are determined based on the points at the intersections formed by three or more lines. With the bifurcation point as the center, the eight adjacent coordinates are assigned a value of 0 to segment the fiber skeleton diagram. The fiber skeleton diagram is numbered as in step (3), and a set of skeleton segment coordinates corresponding to each number is obtained.

[0035] (7) For the skeleton with the same number in the fiber skeleton diagram, perform graphical expansion. Each expansion will increase the distance by one pixel unit. The fiber coordinate point whose distance from the skeleton with the same number is equal to the expansion distance is marked as the fiber segment image point. When the number of newly added fiber segment image points after expansion is less than the critical number of fiber segment image points, stop the expansion, record the coordinates of the fiber segment image points and the skeleton coordinates during this process, and save them in the fiber segment coordinate set with the same number as the skeleton segment coordinate set;

[0036] (8) traversing each fiber segment coordinate set, taking the number of coordinates in the fiber segment coordinate set as the fiber segment area, taking the number of coordinates in the corresponding skeleton segment coordinate set as the fiber segment length, and calculating the fiber segment width by dividing the fiber segment area by the fiber segment length, and establishing a fiber segment set, wherein each fiber segment includes information on the mapping of the fiber segment area, the fiber segment length, the fiber segment width, and the skeleton segment coordinate set;

[0037] (9) The fiber segment with the maximum fiber width is taken as the main fiber, and the fiber segment set and the skeleton segment coordinate set mapped to it are saved in the main fiber set and the main fiber skeleton coordinate set respectively. The fiber segment set with a fiber width greater than the critical fiber width is traversed. When the distance between the two end point coordinates of the main fiber skeleton coordinate set and the two end point coordinates of the traversed skeleton segment coordinate set is less than the critical distance, all the coordinates of the skeleton segment are merged into the main fiber skeleton set, and the corresponding fiber segment is merged into the main fiber set at the same time;

[0038] (10) Repeat step (9) until the main fiber set cannot be updated and the main fiber set (corresponding coordinate image is as follows) is obtained. Figure 1 d), then delete the main fiber set in the fiber segment set, and the remaining fiber segment set is recorded as the filament set;

[0039] (11) Based on the main fiber set and the filament set, the total filament length, average filament length, main fiber length, total filament area and main fiber area were calculated. The fibrilization index was characterized by four different methods: the first was the total filament length / main fiber length, the second was the total filament area / main fiber area, the third was the average filament length / main fiber length, and the fourth was the average filament area / main fiber area.

[0040] (12) repeating steps (4) to (11) to calculate the fiber splitting index of all fibers in the fiber image;

[0041] The number of critical fiber segment image points described in step (7) is 1.2×the fiber skeleton length.

[0042] The critical fiber width described in step (9) is 0.5×maximum fiber width, and the critical distance is 5 pixel distance.

[0043] The measurement method based on the calculation method of the above-mentioned plant fiber fibrillation index is as follows: place the detection cell on the stage of the optical digital microscope, one end of the detection cell is connected to the beaker, and the other end is connected to the peristaltic pump, the hose at the other end of the peristaltic pump is placed in the beaker, and the beaker is placed on the magnetic stirrer; add 0.001% concentration of fiber suspension to the beaker, turn on the magnetic stirrer, and after stabilization, turn on the peristaltic pump. When the fiber suspension flows back to the beaker, the peristaltic pump is set to run for 1 second and pause for 1 second in a cycle, and the fiber image is taken during the pause.

[0044] The above-mentioned detection pool is a rectangular parallelepiped, and its observation surface and light-transmitting surface are opposite and both are flat. A capillary with a diameter of 0.15 mm is fixed in the middle of the detection pool, and both ends of the capillary are connected to the inlet and outlet pipes.

Claims

1. A method for calculating the fiber fibrillation index of plant fibers, characterized in that The following steps are involved: (1) The image of the plant fiber is obtained by taking pictures with an optical digital microscope; (2) converting the fiber image into a grayscale image, and then performing binarization and color inversion in sequence to obtain a binarized color inversion image; (3) based on a graphical algorithm, the fibers that are not at the edge of the binary inverted image are numbered in sequence to obtain a numbering matrix; (4) For a fiber with a certain serial number, a fiber template binary image with a size of [1: Xmax-Xmin+1, 1: Ymax-Ymin+1] is established based on the minimum value Xmin and maximum value Xmax of the first dimension of the fiber coordinates and the minimum value Ymin and maximum value Ymax of the second dimension. The fiber is mapped from the binary inverted image to the fiber template binary image, so that the value of the fiber coordinate in the fiber template binary image is 1, and the value of the non-fiber coordinate is 0; (5) skeletonizing the fiber template binary image to obtain a fiber skeleton image; (6) For the fiber skeleton diagram, the coordinates of the bifurcation points are determined based on the points at the intersections formed by three or more lines. With the bifurcation point as the center, the eight adjacent coordinates are assigned a value of 0 to segment the fiber skeleton diagram. The fiber skeleton diagram is numbered as in step (3), and a set of skeleton segment coordinates corresponding to each number is obtained. (7) For the skeleton with the same number in the fiber skeleton diagram, perform graphical expansion. Each expansion will increase the distance by one pixel unit. The fiber coordinate point whose distance from the skeleton with the same number is equal to the expansion distance is marked as the fiber segment image point. When the number of newly added fiber segment image points after expansion is less than the critical number of fiber segment image points, stop the expansion, record the coordinates of the fiber segment image points and the skeleton coordinates during this process, and save them in the fiber segment coordinate set with the same number as the skeleton segment coordinate set; (8) traversing each fiber segment coordinate set, taking the number of coordinates in the fiber segment coordinate set as the fiber segment area, taking the number of coordinates in the corresponding skeleton segment coordinate set as the fiber segment length, and calculating the fiber segment width by dividing the fiber segment area by the fiber segment length, and establishing a fiber segment set, wherein each fiber segment includes information on the mapping of the fiber segment area, the fiber segment length, the fiber segment width, and the skeleton segment coordinate set; (9) The fiber segment with the maximum fiber width is taken as the main fiber, and the fiber segment set and the skeleton segment coordinate set mapped to it are saved in the main fiber set and the main fiber skeleton coordinate set respectively. The fiber segment set with a fiber width greater than the critical fiber width is traversed. When the distance between the two end point coordinates of the main fiber skeleton coordinate set and the two end point coordinates of the traversed skeleton segment coordinate set is less than the critical distance, all the coordinates of the skeleton segment are merged into the main fiber skeleton set, and the corresponding fiber segment is merged into the main fiber set at the same time; (10) Repeat step (9) until the main fiber set cannot be updated, and then the main fiber set in the fiber segment set is deleted, and the remaining fiber segment set is recorded as the fiber set; (11) Based on the main fiber set and the filament set, the total filament length, average filament length, main fiber length, total filament area and main fiber area were calculated. The fibrilization index was characterized by three different methods: the first was the total filament length / main fiber length, the second was the total filament area / main fiber area, the third was the average filament length / main fiber length, and the fourth was the average filament area / main fiber area. (12) Repeat steps (4) to (11) to calculate the fiber fibrillation index of all fibers in the fiber image.

2. The method for calculating the plant fiber fibrillation index according to claim 1, characterized in that: The number of critical fiber segment image points described in step (7) is (1.1-1.3)×fiber skeleton length.

3. The method for calculating the plant fiber filamentation index according to claim 1, characterized in that: The critical fiber width described in step (9) is (0.5-0.8)×maximum fiber width, and the critical distance is 3-8 pixel distances.

4. The method for measuring the calculation method of the plant fiber filamentation index according to claims 1-3, characterized in that: The detection pool is placed on the stage of the optical digital microscope, one end of the detection pool is connected to the beaker, and the other end is connected to the peristaltic pump. The hose at the other end of the peristaltic pump is placed in the beaker, and the beaker is placed on the magnetic stirrer; 0.0005%-0.01% fiber suspension is added to the beaker, the magnetic stirrer is turned on, and after stabilization, the peristaltic pump is turned on. When the fiber suspension flows back to the beaker, the peristaltic pump is set to run for 1 second and pause for 1 second in a cycle, and the fiber image is taken during the pause.

5. The measuring method according to claim 4, characterized in that: The detection pool is a rectangular parallelepiped, with an observation surface and a light-transmitting surface facing each other and both being planes. A capillary tube with a diameter of 0.1-0.2 mm is fixed in the middle of the detection pool, and both ends of the capillary tube are connected to water inlet and outlet pipes.

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