A blood flow imaging method, device and storage medium based on visible light images

Abstract

The present invention relates to a blood flow imaging method, device and storage medium based on visible light images. The method includes: acquiring visible light images of the skin wound site in real time; performing grayscale processing on the visible light images to obtain grayscale images; calculating the absolute value of the difference between the pixel value of each pixel point in the current frame and the previous frame in the grayscale image, denoted as the pixel difference; calculating the sum of the pixel value of each pixel point in the current frame and the previous frame in the grayscale image, denoted as the pixel sum; determining the pixel weighting value L of each pixel point based on the pixel difference and the pixel sum; adjusting the pixel weighting value L based on a pre-configured adjustment coefficient m to obtain the pixel Q value; performing threshold processing on the pixel Q value based on a simple rule; performing smoothing processing on the pixel Q value based on a filtering technique; mapping the pixel Q value corresponding to each pixel point onto a pseudo-color image to obtain a blood flow imaging map. Compared with the prior art, the present invention has the advantages of low requirements for the relative pose and stability of the acquisition device, strong practicability, etc.

Description

Technical Field

[0001] The present invention relates to the field of digital image processing, and in particular to a blood flow imaging method, device and storage medium based on visible light images. Background Art

[0002] Blood flow imaging technology, as a cutting-edge detection technology in the medical field, is commonly used in fields such as skin imaging and brain imaging. For example, laser speckle contrast imaging (LSCI), as a simple and low-cost method, can obtain a two-dimensional blood flow perfusion map of the entire field of view and provide a dynamic description of blood flow changes in real time. Therefore, it can be used as an intraoperative blood flow monitoring tool.

[0003] The main principle of current traditional blood flow imaging technology is to irradiate the skin surface to be detected with a near-infrared laser, then use a camera to collect the laser reflected by the skin surface, and process the resulting image to obtain a reference result. This method is used more in academic research fields and animal experiments, but it is more difficult to promote in clinical use. The reason is that this method has strict requirements on the relative pose relationship between the laser head, the camera and the detection part, as well as the stability of the parts, and the relatively complex system design makes it difficult to match the complex application scenarios in real clinical situations. Summary of the Invention

[0004] The purpose of the present invention is to provide a blood flow imaging method, device and storage medium based on visible light images, which can achieve blood flow imaging without strict requirements on the pose of the acquisition device relative to the wound surface and the stability of the parts.

[0005] The purpose of the present invention can be achieved by the following technical solutions:

[0006] A blood flow imaging method based on visible light images includes the following steps:

[0007] Obtain in real time a visible light image of the skin wound surface, where the visible light image is obtained by an acquisition device according to a pre-configured sampling interval;

[0008] Perform grayscale processing on the visible light image to obtain a grayscale image;

[0009] Calculate the absolute value of the difference between the pixel value of each pixel point in the current frame and the pixel value of the previous frame in the grayscale image, denoted as the pixel difference. Among them, the pixel difference of the pixel point j in the i-th frame image is

[0010] Calculate the sum of the pixel value of each pixel point in the current frame and the pixel value of the previous frame in the grayscale image, denoted as the pixel sum. Among them, the pixel sum of the pixel point j in the i-th frame image is

[0011] Determine the pixel weighted value L of each pixel point based on the pixel difference and pixel sum, where the pixel weighted value of pixel point j in the i-th frame image is L ij = |K ij - K (i-1)j | / K ij + K (i-1)j );

[0012] Adjust the pixel weighted value L based on a pre-configured adjustment coefficient m to obtain the pixel Q value;

[0013] Perform threshold processing on the pixel Q value based on a pre-configured simple rule;

[0014] Perform smoothing processing on the pixel Q value based on a filtering technique;

[0015] Map the pixel Q value corresponding to each pixel point onto a pseudocolor image to obtain a blood flow imaging map.

[0016] The method of grayscale processing includes the maximum value method, the average value method, and the weighted average method.

[0017] The adjustment of the pixel weighted value L based on a pre-configured adjustment coefficient m to obtain the pixel Q value is: Q = L * m.

[0018] The threshold of the simple rule is configured to 255.

[0019] The filtering technique includes Gaussian filtering, mean filtering, median filtering, and exponential smoothing filtering.

[0020] The mapping algorithm for mapping the pixel Q value corresponding to each pixel point onto a pseudocolor image is colormap_jet.

[0021] The acquisition device is disposed at a pre-configured distance above the skin wound site and is in a stationary state.

[0022] The acquisition device includes a camera.

[0023] A blood flow imaging device based on visible light images, including a memory, a processor, and a program stored in the memory, wherein when the processor executes the program, the method as described above is implemented.

[0024] A storage medium, on which a program is stored, and when the program is executed, the method as described above is implemented.

[0025] Compared with the prior art, the present invention has the following beneficial effects:

[0026] (1) The present invention generates a blood flow map based on the method of calculating the pixel difference between image frames. The calculation method is simple, the calculation speed is fast, and it can generate a blood flow imaging map in real time, and can adapt to different lighting conditions and different acquisition devices.

[0027] (2) The present invention only needs a camera to complete the acquisition work, and there are no strict requirements for the pose of the camera relative to the wound site and the stability of the part. Compared with the existing solutions that usually use a laser emitter and a camera simultaneously to acquire images and need to ensure the stability of both parts at the same time, it simplifies the hardware facilities and installation requirements and has better applicability in actual clinical diagnosis. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 is a flowchart of the method of the present invention;

[0029] Figure 2 is a grayscale image of an embodiment;

[0030] Figure 3 is a blood flow imaging map of an embodiment. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0031] The present invention will be described in detail below with reference to the drawings and specific embodiments. This embodiment is implemented on the premise of the technical solution of the present invention, and gives the detailed implementation manner and specific operation process, but the protection scope of the present invention is not limited to the following embodiments.

[0032] A blood flow imaging method based on visible light images, as Figure 1 shown, includes the following steps:

[0033] (1) Obtain the visible light image of the skin wound site in real time, and the visible light image is obtained by the acquisition device according to the pre-configured sampling interval;

[0034] In this embodiment, the acquisition device is a camera, which is arranged above the skin wound site and is 100 mm - 200 mm away from the skin wound site, and is in a stationary state. The acquisition position of the camera should not be too far away. When the area of the wound site is small, it is necessary to further shorten the distance between the camera and the wound.

[0035] (2) Perform grayscale processing on the visible light image to obtain a grayscale image;

[0036] The methods of the grayscale processing include the maximum value method, the average value method, and the weighted average method. Among them, the maximum value method is: set the values of R, G, and B after grayscale processing to the largest one of the 3 values before grayscale processing; the average value method is: set the values of R, G, and B after grayscale processing to the average value of R, G, and B before grayscale processing; the weighted average method is: perform weighted average on the values of R, G, and B according to a certain weight.

[0037] In this embodiment, the averaging method is used for grayscale conversion, and the obtained grayscale image is as Figure 2 shown.

[0038] (3) Calculate the absolute value of the difference between the pixel value of each pixel point in the grayscale image in the current frame and the pixel value of the previous frame, which is denoted as the pixel difference. Among them, the pixel difference of the pixel point j in the i-th frame image is

[0039] This step is to reflect the richness of wound blood flow through the pixel difference. The blood flow velocity at the damaged part is faster than that at other positions, and the corresponding pixel difference is also larger.

[0040] (4) Calculate the sum of the pixel value of each pixel point in the grayscale image in the current frame and the pixel value of the previous frame, which is denoted as the pixel sum. Among them, the pixel sum of the pixel point j in the i-th frame image is

[0041] This step is to determine the pixel sum and assign the pixel sum as a weight to the corresponding pixel differences in the subsequent steps.

[0042] (5) Determine the pixel weighted value L of each pixel point based on the pixel difference and the pixel sum. Among them, the pixel weighted value of the pixel point j in the i-th frame image is L ij = |K ij - K (i-1)j | / (K ij + K (i-1)j );

[0043] The larger the pixel value of the current frame, the smaller the weight it obtains. The smaller the pixel value of the current frame, the larger the weight it obtains. Therefore, after this step, some pixel points with small pixel values in the areas with rich blood flow and severe wounds will be enhanced by a large margin, while some pixel points with large pixel values in the smaller areas will be weakened by a large margin. This step can effectively reduce the problem that the blood flow area image is not prominent due to the influence of environmental light and the like.

[0044] (6) Adjust the pixel weighted value L based on a pre-configured adjustment coefficient m to obtain the pixel Q value: Q = L * m;

[0045] In the actual scenario, the user can adjust the contrast of the image through the adjustment coefficient m.

[0046] (7) Perform threshold processing on the pixel Q value based on a simple rule, and the threshold of the simple rule is configured to 255;

[0047] After a series of calculations in the above steps, the pixel values will be relatively large. The purpose of setting the threshold is to reassign the pixel point values to the normal range.

[0048] (8) Smooth the pixel Q value based on filtering technology;

[0049] In this embodiment, the Gaussian filtering technology is adopted, and the Gaussian matrix is set to (5, 5) with a standard deviation of 0.

[0050] (9) Map the pixel Q value corresponding to each pixel point to a pseudocolor image based on the colormap_jet mapping algorithm to obtain a blood flow imaging map, as Figure 3 shown.

[0051] When the acquisition device is in the on state, the above steps will be continuously looped, and then based on the real-time updated visible light image, a real-time blood flow imaging map will be obtained. Therefore, after obtaining a certain blood flow imaging map, it is necessary to judge the on state of the acquisition device. If the acquisition device is in the on state, enter the loop to obtain the next frame of visible light image. If the acquisition device is in the off state, exit the program and end the loop.

[0052] If the above functions are implemented in the form of software functional units and sold or used as independent products, they can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention, in essence, or the part that makes contributions to the prior art, or part of this technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to enable a computer device (which can be a personal computer, a server, or a network device, etc.) to execute all or part of the steps of the methods described in various embodiments of the present invention. The aforementioned storage medium includes: various media such as USB flash drives, mobile hard disks, read-only memories (ROM, Read-Only Memory), random access memories (RAM, Random Access Memory), magnetic disks, or optical discs that can store program codes.

[0053] The preferred specific embodiments of the present invention have been described in detail above. It should be understood that those of ordinary skill in the art can make many modifications and variations based on the concept of the present invention without creative labor. Therefore, all technical solutions that can be obtained by those skilled in the art in the technical field of the present invention based on the concept of the present invention through logical analysis, reasoning, or limited experiments on the basis of the prior art should be within the protection scope determined by the claims.

Claims

1. A blood flow imaging method based on visible light images, characterized in that, Including the following steps: Obtain a visible light image of the skin wound site in real time, where the visible light image is obtained by a collection device according to a pre-configured sampling interval; Perform grayscale processing on the visible light image to obtain a grayscale image; Calculate the absolute value of the difference between the pixel value of each pixel point in the current frame and the pixel value of the previous frame in the grayscale image, which is denoted as the pixel difference. Among them, the i pixel point in the j frame image has a pixel difference of ; Calculate the sum of the pixel value of each pixel point in the grayscale image in the current frame and the pixel value of the previous frame, and record it as the pixel sum. Among them, the pixel sum of the pixel point i in the j frame image is ; Determine the pixel weighted value of each pixel point based on the pixel difference and pixel sum , where the pixel weighted value of the pixel point i in the j nth frame image is ; Based on a pre-configured adjustment coefficient m Adjust the pixel weighting value to obtain the pixel Q value: Q = L * m ; Threshold the pixel values based on a pre-configured simple rule, where the threshold of the simple rule is configured to be 255; Q ​ Smoothing the pixel Q values based on filtering technology; Map the pixel values corresponding to each pixel point Q onto a pseudocolor image to obtain a blood flow imaging map. The mapping algorithm for mapping the pixel Q values corresponding to each pixel point onto the pseudocolor image is colormap_jet.

2. The method for blood flow imaging based on visible light images according to claim 1, wherein The methods of the grayscale processing include the maximum value method, the average value method, and the weighted average method.

3. The method for blood flow imaging based on visible light images according to claim 1, characterized in that, The filtering techniques include Gaussian filtering, mean filtering, median filtering, and exponential smoothing filtering.

4. A method for blood flow imaging based on visible light images according to claim 1, characterized in that, The collection device is disposed at a pre-configured distance above the skin wound site and is in a stationary state.

5. The blood flow imaging method based on visible light images according to claim 1, wherein The collection device includes a camera.

6. A blood flow imaging device based on visible light images, comprising a memory, a processor, and a program stored in the memory, characterized in that, When the processor executes the program, it implements the method described in any one of claims 1-5.

7. A storage medium having a program stored thereon, characterized in that, When the program is executed, it implements the method described in any one of claims 1-5.

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