Arterial blood oxygen saturation measurement method and device based on dual-color light arterial blood vessel image

Abstract

The present invention discloses an arterial blood oxygen saturation measurement method and device based on a dual-color light arterial blood vessel image, which includes the following steps: 1) irradiating a target part with light beams of wavelengths λ1 and λ2 respectively, collecting light signals after light transmission at two different wavelengths, and converting the light signals into image digital signals; 2) performing image enhancement processing and binarization processing on the two obtained image digital signals respectively; 3) calculating the expansion optical path and contraction optical path of the arterial blood vessel generated by the arterial blood vessel pulsation at wavelengths λ1 and λ2 respectively according to the two enhanced and binarized image digital signals; 4) calculating the arterial blood oxygen saturation according to the expansion optical path and contraction optical path of the arterial blood vessel at two wavelengths, which is used to reflect the blood oxygen content of the human body. The present invention provides the possibility of miniaturization and low cost of blood oxygen detection equipment, and provides a new detection scheme for the detection of the concentration of non-invasive oxygenated hemoglobin.

Description

Technical Field

[0001] The present invention relates to the technical field of image recognition and processing, and in particular to a method and device for measuring arterial blood oxygen saturation based on a dual-color light arterial blood vessel image. Background Art

[0002] The principle of non-invasive blood oxygen saturation measurement is that arterial pulsation causes changes in the absorption of light by the blood, and the changes in light are converted into electrical signals, which are then processed to calculate the blood oxygen saturation. Blood oxygen saturation is generally expressed as the percentage of oxygenated hemoglobin in the blood to the total hemoglobin. Generally, the functional blood oxygen saturation (SpO2) of the artery is monitored to reflect the blood oxygen content of the human body. The expression is:

[0003]

[0004] Among them, SpO2 is blood oxygen saturation; is the concentration of oxygenated hemoglobin in the arteries; C Hb It is the concentration of reduced hemoglobin in arteries.

[0005] The current medical transmission-type non-invasive blood oxygen saturation measurement solution adopts a dual-wavelength asynchronous illumination solution, such as Figure 1 As shown, two light-emitting diodes placed side by side are fixed on the upper wall of the finger, with wavelengths of 660nm red light and 904nm infrared light respectively, and the lower wall is a photoelectric conversion device, which converts the intensity of the transmitted light into a current signal. By controlling the two LEDs to emit light in turn, and performing I / V conversion on the current signals output when each light is emitted, amplifying and then collecting, processing the collected signals, obtaining the corresponding pulse wave data, and finally calculating the SpO2 value. The method for obtaining blood oxygen saturation in this scheme is like the dual-wavelength venous blood oxygen saturation measurement method without correction disclosed in Chinese patent CN112903609A, which includes the following steps: controlling the emission of red light and infrared light diodes through DAC, using an optical frequency sensor to receive the transmitted light, converting the transmitted light signal into the corresponding frequency signal f, and then uploading the obtained frequency data f and f′ to the computer through MCU, and then calculating the blood oxygen saturation through the derived formula.

[0006] However, the existing blood oxygen saturation measurement technology requires a dual-wavelength asynchronous lighting solution, and requires a complex photoelectric conversion device and signal processing unit. The calculation process is cumbersome and the calculation accuracy is not high. The acquisition module requires a complex photoelectric conversion device, the equipment is difficult to miniaturize, and the equipment cost is high. Summary of the invention

[0007] The purpose of the present invention is to provide a method and device for measuring arterial blood oxygen saturation based on dual-color light arterial blood vessel images, so as to solve the problems of complicated calculation process, low precision and high acquisition module cost in optical signal processing.

[0008] In order to achieve the purpose, the technical solution provided by the present invention is:

[0009] The present invention relates to a method for measuring arterial blood oxygen saturation based on a dual-color light arterial blood vessel image, which comprises the following steps:

[0010] 1) Use light beams with wavelengths of λ1 and λ2 to illuminate the target part respectively, collect light signals after light transmission at two different wavelengths, and convert the light signals into image digital signals;

[0011] 2) performing image enhancement processing and binarization processing on the two sets of image digital signals obtained respectively;

[0012] 3) Calculate the expansion optical path and contraction optical path of the arterial blood vessels caused by the pulsation of the arterial blood vessels at wavelengths λ1 and λ2 respectively according to the two sets of enhanced and binarized image digital signals;

[0013] 4) The arterial blood oxygen saturation is calculated based on the expansion and contraction optical paths of the arterial blood vessels under two wavelengths to reflect the blood oxygen content of the human body.

[0014] Preferably, the specific steps of performing image enhancement processing and binarization processing on the image digital signal in step 2) include:

[0015] 2.1) Calculate the curvature value of each pixel in the image sequence;

[0016] 2.2) Calculate the mean curvature of all pixels in the image sequence;

[0017] 2.3) The arteries are binarized according to the curvature value of each pixel in the image sequence and the mean curvature of all pixels.

[0018] Preferably, in step 2.1), the calculation formula for the curvature value of each pixel in the image sequence is as follows:

[0019]

[0020] in,

[0021]

[0022]

[0023]

[0024]

[0025]

[0026] In the formula, C ij Img is the curvature value of the pixel in the i-th row and j-th column of the image sequence; ij is the gray value of the pixel in the i-th row and j-th column of the image sequence; p ij is the first-order partial derivative of the pixel in the i-th row and j-th column of the image sequence in the x-axis direction; q ij is the first-order partial derivative of the pixel in the i-th row and j-th column of the image sequence in the y-axis direction; r ij is the second-order partial derivative of the pixel in the i-th row and j-th column of the image sequence in the x-axis direction; t ij is the second-order partial derivative of the pixel in the i-th row and j-th column of the image sequence in the y-axis direction; s ij is the second-order mixed partial derivative of the pixel in the i-th row and j-th column of the image sequence in the x-axis direction and the y-axis direction;

[0027] The calculation formula of the curvature mean of all pixels in the image sequence in step 2.2) is as follows:

[0028]

[0029] Among them, C avg is the mean curvature of all pixels in the image sequence; r is the number of image rows in the image sequence; c is the number of image columns in the image sequence.

[0030] Preferably, in step 2.3), the calculation method of the binarization process is:

[0031]

[0032] Among them, f ij is the binarized value of the pixel in the i-th row and j-th column of the image sequence; α is the curvature mean binarization coefficient, and its value range is [0, 1].

[0033] Preferably, the value of the curvature mean binarization coefficient α is 0.5.

[0034] Preferably, in step 3), the expansion optical path and the contraction optical path at the current wavelength are calculated based on the binarized effective areas of the two groups of image digital signals after enhancement processing and binarization processing.

[0035] Preferably, the specific calculation formula for calculating the expansion optical path and the contraction optical path at the current wavelength based on the binary effective area of ​​the two sets of image digital signals after enhancement processing and binary processing is:

[0036]

[0037] Smax =max{S1, S2, S3, ..., S A} (10)

[0038] S min =min(S1, S2, S3, ..., S A} (11)

[0039] L max =S max (13)

[0040] L min =S min (16)

[0041] In the formula, S m is the effective area of ​​the arterial blood vessel binarization of the mth image sequence; is the binary value of the pixel in the i-th row and j-th column of the m-th image sequence; S max is the binary effective area when the artery is dilated; S min is the binary effective area when the artery contracts; A is the number of image digital signals acquired at the current wavelength; L max L is the optical path length when the artery is dilated; min It is the light path length when the artery contracts.

[0042] Preferably, the specific steps of calculating the arterial blood oxygen saturation according to the expansion optical path and contraction optical path of the arterial blood vessel in step 4) include:

[0043] 4.1) Calculate the intensity of the transmitted light when the artery is dilated. The calculation formula is as follows:

[0044]

[0045]

[0046] In the formula, I A is the intensity of the transmitted light when the artery is dilated; I0 is the intensity of the incident light when the artery is dilated; γ is the absorption coefficient of the non-pulsating components in the tissue and venous blood; ε HbO2 C is the absorption coefficient of oxygenated hemoglobin in arterial blood vessels; HbO2 is the concentration of oxygenated hemoglobin in arteries; Hb C is the absorption coefficient of reduced hemoglobin in arterial blood vessels; Hb To indicate the concentration of reduced hemoglobin in arterial blood vessels; is the gray value of the pixel in the i-th row and j-th column of the artery dilation image sequence; is the binary value of the pixel in the i-th row and j-th column of the artery dilation image sequence; r1 is the image row number of the artery dilation image sequence; c1 is the image column number of the artery dilation image sequence;

[0047] 4.2) Calculate the intensity of the transmitted light when the artery contracts. The calculation formula is as follows:

[0048]

[0049]

[0050] In the formula, I B is the intensity of the transmitted light when the artery contracts; I0' is the intensity of the incident light when the artery contracts; is the gray value of the pixel in the i-th row and j-th column of the arterial contraction image sequence; is the binary value of the pixel in the i-th row and j-th column of the arterial contraction image sequence; r2 is the number of image rows in the arterial contraction image sequence; c2 is the number of image columns in the arterial contraction image sequence;

[0051] 4.3) Integrate and take logarithms of formulas (12) to (14) to obtain formula (18):

[0052]

[0053] 4.4) Integrate and logarithm formulas (15) to (17) to obtain formula (19):

[0054]

[0055] 4.5) Integrate formulas (18) to (19) to obtain formulas (20) and (21), which are used to calculate the quantitative parameters of the pulsation information of the arterial blood vessels:

[0056] C HbO2 ε HbO2 +C Hb ε Hb =R (20)

[0057]

[0058] In the formula, R is the quantitative parameter of the pulsation information of the arterial blood vessels.

[0059] Substitute the two sets of image digital signals obtained when the wavelength is λ1 and λ2 into formula (21) respectively, and calculate the quantitative parameters of the pulsation information of the arterial blood vessels when the incident light wavelength is λ1 The quantitative parameters of the pulsation information of the arterial blood vessels when the incident light wavelength is λ2

[0060] 4.6) According to formula (20), the calculation formula for the quantitative parameters of the pulsation information of the arterial blood vessels under the illumination of two wavelengths λ1 and λ2 is obtained:

[0061]

[0062]

[0063] In the formula, is the absorption coefficient of oxygenated hemoglobin in the arterial blood vessel when the wavelength of incident light is λ1; is the absorption coefficient of reduced hemoglobin in the arterial blood vessel when the incident light wavelength is λ1; is the absorption coefficient of oxygenated hemoglobin in the arterial blood vessel when the wavelength of incident light is λ2; is the absorption coefficient of reduced hemoglobin in the arterial blood vessel when the incident light wavelength is λ2;

[0064] 4.7) Integrate formulas (22) to (23) to obtain formula (24):

[0065]

[0066] 4.8) The calculation formula of arterial blood oxygen saturation is obtained according to formula (24), and the arterial blood oxygen saturation is calculated. The calculation formula of arterial blood oxygen saturation is:

[0067]

[0068] In the formula, SpO2 is the arterial oxygen saturation; is the concentration of oxygenated hemoglobin in the arteries; C Hb It is the concentration of reduced hemoglobin in arteries.

[0069] Preferably, in the step 1), a camera device is used to collect light signals after light transmission at two different wavelengths, the frame rate of the camera device is 60 frames / s, the target part is placed for at least 1 second under the irradiation of each wavelength of the light beam, and at least 60 image digital signals of the current wavelength are obtained.

[0070] The present invention also relates to an arterial blood oxygen saturation measurement device based on a dual-color light arterial blood vessel image, comprising:

[0071] The acquisition module irradiates the target part with light beams of wavelengths λ1 and λ2 respectively, collects the light signals after light transmission at two different wavelengths, and converts the light signals into image digital signals;

[0072] An image processing module is used to perform image enhancement processing and binarization processing on the two sets of image digital signals obtained;

[0073] An optical path calculation module is used to calculate the expansion optical path and contraction optical path of the arterial blood vessels generated by the pulsation of the arterial blood vessels at wavelengths of λ1 and λ2 respectively according to two groups of enhanced and binarized image digital signals;

[0074] The arterial blood oxygen saturation calculation module is used to calculate the arterial blood oxygen saturation according to the expansion optical path and contraction optical path of the arterial blood vessels under two wavelengths, so as to reflect the blood oxygen content of the human body.

[0075] Compared with the prior art, the technical solution provided by the present invention has the following beneficial effects:

[0076] 1. The present invention adopts a method for measuring arterial blood oxygen saturation based on a two-color light arterial blood vessel image, which can directly obtain the pulsation information of the arterial blood vessels and perform accurate quantitative calculations without the need for complex photoelectric conversion devices, thus providing a possibility for miniaturization and low cost of blood oxygen detection equipment.

[0077] 2. The present invention adopts a method for measuring arterial oxygen saturation based on a two-color light arterial blood vessel image to directly calculate the value of arterial oxygen saturation, without the need to use an empirical formula for numerical simulation calculation of arterial oxygen saturation. The calculation process is simple and the calculation accuracy is high. BRIEF DESCRIPTION OF THE DRAWINGS

[0078] Figure 1 It is a schematic diagram of the existing transmission-type dual-wavelength arterial blood oxygen saturation measurement method;

[0079] Figure 2 It is a flow chart of a method for measuring arterial blood oxygen saturation based on dual-color light arterial blood vessel images;

[0080] Figure 3 It is a schematic diagram of collecting image digital signals;

[0081] Figure 4 It is a framework diagram of an arterial blood oxygen saturation measurement device based on a two-color light arterial blood vessel image. DETAILED DESCRIPTION

[0082] In order to further understand the content of the present invention, the present invention is described in detail in conjunction with examples. The following examples are used to illustrate the present invention but are not used to limit the scope of the present invention.

[0083] Embodiment 1

[0084] Refer to the attached Figure 2 As shown, the method for measuring arterial blood oxygen saturation based on dual-color light arterial blood vessel images involved in this embodiment includes the following steps:

[0085] 1) Refer to the attached Figure 3As shown, a finger is placed in a collection module, a two-color photodiode is provided on the top of the collection module, the two-color photodiode can emit light of two different wavelengths, a camera device is provided on the bottom, and the finger is placed between the two-color photodiode and the camera; the camera device can obtain two groups of light signals after light transmission at different wavelengths, and convert the obtained two groups of light signals into image digital signals; the frame rate of the camera device is N frames / s, the finger is placed under the irradiation of each wavelength of light for at least Ts, and the image digital signals of each group of current wavelengths obtained are NT frames;

[0086] In this embodiment, the two-color photodiode can emit red light of 660nm and infrared light of 904nm respectively, that is, λ1=660nm, λ2=904nm; N is 60 frames / s, T is 1s, and 60 image digital signals under the wavelength of 660nm red light and 904nm infrared light are obtained respectively. The image digital signal sets {fvImg} of the two groups of fingers obtained are:

[0087] {fvImg} 660nm ={fvImg1, fvImg2, fvImg3,..., fvImg 60} 660nm (26)

[0088] {fvImg} 904nm ={fvImg1, fvImg2, fvImg3,..., fvImg 60} 904nm (27)

[0089] It should be noted that, in this embodiment, the two-color light diode is placed above the part to be collected, and the camera device is arranged below the part to be collected; in other implementation schemes, the two-color light diode and the camera device can also be placed on the left and right sides of the target part respectively, or the two-color light diode and the camera device can be placed on the same side of the target part.

[0090] It should be noted that, in this embodiment, the collection site is a finger, and in other embodiments, the collection site may also be other sites containing arterial blood vessels such as the palm or face.

[0091] 2) Performing image enhancement processing and binarization processing on the two sets of image digital signals respectively, the specific steps of which include:

[0092] 2.1) Calculate the curvature value of each pixel in the image sequence. The curvature calculation formula is as follows:

[0093]

[0094] in,

[0095]

[0096]

[0097]

[0098]

[0099]

[0100] In the formula, C ij Img is the curvature value of the pixel in the i-th row and j-th column of the image sequence; ij is the gray value of the pixel in the i-th row and j-th column of the image sequence; p ij is the first-order partial derivative of the pixel in the i-th row and j-th column of the image sequence in the x-axis direction; q ij is the first-order partial derivative of the pixel in the i-th row and j-th column of the image sequence in the y-axis direction; r ij is the second-order partial derivative of the pixel in the i-th row and j-th column of the image sequence in the x-axis direction; t ij is the second-order partial derivative of the pixel in the i-th row and j-th column of the image sequence in the y-axis direction; s ij is the second-order mixed partial derivative of the pixel in the i-th row and j-th column of the image sequence in the x-axis direction and the y-axis direction;

[0101] 2.2) Calculate the mean curvature of all pixels in the image sequence. The calculation formula of the mean curvature is as follows:

[0102]

[0103] Among them, C avg is the mean curvature of all pixels in a certain image sequence; r is the number of image rows in a certain image sequence; c is the number of image columns in a certain image sequence;

[0104] 2.3) According to the curvature value of each pixel in the image sequence and the mean curvature value of all pixels, the artery is binarized. The binarization calculation method is:

[0105]

[0106] Among them, f ij is the binarized value of the pixel in the i-th row and j-th column of the image sequence; α is the curvature mean binarization coefficient, and its value range is [0, 1]. In this embodiment, the value of α is 0.5;

[0107] 3) The expansion optical path and contraction optical path of the arterial blood vessels generated by the pulsation of the arterial blood vessels are calculated based on the two sets of enhanced and binarized image digital signals. The calculation formula is:

[0108]

[0109] S max =max{S1, S2, S3, ..., S A} (10)

[0110] S min =min{S1, S2, S3, ..., S A} (11)

[0111] L max =S max (13)

[0112] L min =S min (16)

[0113] In the formula, S m is the effective area of ​​the arterial blood vessel binarization of the mth image sequence; is the binary value of the pixel in the i-th row and j-th column of the m-th image sequence; S max is the binary effective area when the artery is dilated; S min is the binary effective area when the artery contracts, A is the number of image digital signals acquired at the current wavelength; L max L is the optical path length when the artery is dilated; min is the optical path length when the artery contracts; in this embodiment A, it is 60. This step is beneficial to reduce the calculation error of arterial blood oxygen saturation.

[0114] 4) Calculating arterial blood oxygen saturation according to the expansion optical path and contraction optical path of the arterial blood vessels under two wavelengths to reflect the blood oxygen content of the human body, and the specific steps include:

[0115] 4.1) Calculate the intensity of the transmitted light when the artery is dilated. The calculation formula is as follows:

[0116]

[0117]

[0118] In the formula, I A is the intensity of the transmitted light when the artery is dilated; I0 is the intensity of the incident light when the artery is dilated; γ is the absorption coefficient of the non-pulsating components in the tissue and venous blood; ε HbO2 C is the absorption coefficient of oxygenated hemoglobin in arterial blood vessels; HbO2 is the concentration of oxygenated hemoglobin in arteries; Hb C is the absorption coefficient of reduced hemoglobin in arterial blood vessels; Hb To indicate the concentration of reduced hemoglobin in arterial blood vessels; is the gray value of the pixel in the i-th row and j-th column of the artery dilation image sequence; is the binary value of the pixel in the i-th row and j-th column of the artery dilation image sequence; r1 is the image row number of the artery dilation image sequence; c1 is the image column number of the artery dilation image sequence;

[0119] 4.2) Calculate the intensity of the transmitted light when the artery contracts. The calculation formula is as follows:

[0120]

[0121]

[0122] In the formula, I B is the intensity of the transmitted light when the artery contracts; I0' is the intensity of the incident light when the artery contracts; is the gray value of the pixel in the i-th row and j-th column of the arterial contraction image sequence; is the binary value of the pixel in the i-th row and j-th column of the arterial contraction image sequence; r2 is the number of image rows in the arterial contraction image sequence; c2 is the number of image columns in the arterial contraction image sequence;

[0123] 4.3) Integrate and take logarithms of formulas (12) to (14) to obtain formula (18):

[0124]

[0125] 4.4) Integrate and logarithm formulas (15) to (17) to obtain formula (19):

[0126]

[0127] 4.5) Integrate formulas (18) to (19) to obtain formulas (20) and (21), which are used to calculate the quantitative parameters of the pulsation information of the arterial blood vessels:

[0128] C HbO2 ε HbO2 +C Hb ε Hb =R (20)

[0129]

[0130] In the formula, R is the quantitative parameter of the pulsation information of the arterial blood vessels.

[0131] Substitute the two sets of image digital signals obtained when the wavelength is λ1 and λ2 into formula (21) respectively, and calculate the quantitative parameters of the pulsation information of the arterial blood vessels when the incident light wavelength is λ1 The quantitative parameters of the pulsation information of the arterial blood vessels when the incident light wavelength is λ2

[0132] 4.6) According to formula (20), the calculation formula for the quantitative parameters of the pulsation information of the arterial blood vessels under two wavelengths of illumination is:

[0133]

[0134]

[0135] In the formula, is the absorption coefficient of oxygenated hemoglobin in the arterial blood vessel when the wavelength of incident light is λ1; is the absorption coefficient of reduced hemoglobin in the arterial blood vessel when the incident light wavelength is λ1; is the absorption coefficient of oxygenated hemoglobin in the arterial blood vessel when the wavelength of incident light is λ2; is the absorption coefficient of reduced hemoglobin in the arterial blood vessel when the incident light wavelength is λ2;

[0136] 4.7) Integrate formulas (22) to (23) to obtain formula (24):

[0137]

[0138] 4.8) According to formula (24), a calculation formula for arterial oxygen saturation is obtained, that is, formula (24) is substituted into formula (28) of the background technology to obtain a new calculation formula for arterial oxygen saturation, and the new calculation formula for arterial oxygen saturation is used to calculate arterial oxygen saturation. Arterial oxygen saturation is used to reflect the blood oxygen content of the human body. The calculation formula for arterial oxygen saturation is:

[0139]

[0140] In the formula, SpO2 is the arterial oxygen saturation; is the concentration of oxygenated hemoglobin in the arteries; C Hb It is the concentration of reduced hemoglobin in arteries.

[0141] Effect Example

[0142] In this embodiment, 200 test subjects are randomly selected, and the arterial blood oxygen saturation of the 200 test subjects is measured using two test methods respectively.

[0143] Method 1: Use the traditional arterial oxygen saturation measurement method to collect blood from the human artery, use a blood gas analyzer to perform electrochemical analysis, measure the blood oxygen partial pressure PO2, and calculate the arterial oxygen saturation.

[0144] Method 2: Use the device of the present invention to collect images and calculate arterial blood oxygen saturation.

[0145] The 200 groups of arterial oxygen saturation obtained in method 2 are compared with the arterial oxygen saturation of the corresponding test subjects obtained in method 1. When the error of arterial oxygen saturation is less than 1%, it is proved that the test result of the blood oxygen content status measuring device based on monochromatic light arterial blood vessel image used in method 2 is accurate, otherwise it means that the test result of the device is inaccurate. Through the test of 200-bit test, it is calculated that the accuracy of the arterial oxygen saturation measuring device based on dual-color light arterial blood vessel image of the present invention is as high as 99.5%, thus proving that the arterial oxygen saturation measuring method and device based on dual-color light arterial blood vessel image of the present invention is effective.

[0146] Embodiment 2

[0147] See attached Figure 4 The arterial blood oxygen saturation measurement device based on dual-color light arterial blood vessel images comprises:

[0148] The acquisition module irradiates the target part with light beams of wavelengths λ1 and λ2 respectively, collects light signals after light transmission at two different wavelengths, and converts the light signals into image digital signals; the acquisition module is used to implement the function of step 1) of embodiment 1;

[0149] The image processing module performs image enhancement processing and binarization processing on the two sets of image digital signals obtained respectively; the image processing module is used to implement the function of step 2) of embodiment 1.

[0150] An optical path calculation module, used to calculate the expansion optical path and contraction optical path of the arterial blood vessels caused by the pulsation of the arterial blood vessels at wavelengths λ1 and λ2 respectively according to the two groups of enhanced and binarized image digital signals, and the optical path calculation module is used to implement the function of step 3) of embodiment 1;

[0151] 4) An arterial blood oxygen saturation calculation module is used to calculate the arterial blood oxygen saturation according to the expansion optical path and contraction optical path of the arterial blood vessels under two wavelengths, and is used to reflect the blood oxygen content of the human body. The arterial blood oxygen saturation calculation module is used to implement the function of step 4) of Example 1.

[0152] The present invention is described in detail above in conjunction with the embodiments, but the contents described are only preferred embodiments of the present invention and cannot be considered to limit the scope of implementation of the present invention. All equivalent changes and improvements made according to the scope of application of the present invention should still fall within the scope of the patent coverage of the present invention.

Claims

1. A method for measuring arterial blood oxygen saturation based on dual-color light arterial blood vessel images, characterized in that: It includes the following steps: 1) Use light beams with wavelengths of λ1 and λ2 to illuminate the target part respectively, collect light signals after light transmission at two different wavelengths, and convert the light signals into image digital signals; 2) performing image enhancement processing and binarization processing on the two sets of image digital signals obtained respectively; 3) Calculate the expansion optical path and contraction optical path of the arterial blood vessels caused by the pulsation of the arterial blood vessels at wavelengths λ1 and λ2 respectively according to the two sets of enhanced and binarized image digital signals; 4) The arterial blood oxygen saturation is calculated based on the expansion and contraction optical paths of the arterial blood vessels under two wavelengths to reflect the blood oxygen content of the human body.

2. The method for measuring arterial blood oxygen saturation based on dual-color light arterial blood vessel images according to claim 1, characterized in that: The specific steps of performing image enhancement processing and binarization processing on the image digital signal in step 2) include: 2.1) Calculate the curvature value of each pixel in the image sequence; 2.2) Calculate the mean curvature of all pixels in the image sequence; 2.3) The arteries are binarized according to the curvature value of each pixel in the image sequence and the mean curvature of all pixels.

3. The method for measuring arterial blood oxygen saturation based on dual-color light arterial blood vessel images according to claim 2, characterized in that: In the step 2.1), the calculation formula of the curvature value of each pixel in the image sequence is as follows: in, In the formula, C ij Img is the curvature value of the pixel in the i-th row and j-th column of the image sequence; ij is the gray value of the pixel in the i-th row and j-th column of the image sequence; p ij is the first-order partial derivative of the pixel in the i-th row and j-th column of the image sequence in the x-axis direction; q ij is the first-order partial derivative of the pixel in the i-th row and j-th column of the image sequence in the y-axis direction; r ij is the second-order partial derivative of the pixel in the i-th row and j-th column of the image sequence in the x-axis direction; t ij is the second-order partial derivative of the pixel in the i-th row and j-th column of the image sequence in the y-axis direction; s ij is the second-order mixed partial derivative of the pixel in the i-th row and j-th column of the image sequence in the x-axis direction and the y-axis direction; The calculation formula of the curvature mean of all pixels in the image sequence in step 2.2) is as follows: Among them, C avg is the mean curvature of all pixels in the image sequence; r is the number of image rows in the image sequence; c is the number of image columns in the image sequence.

4. The method for measuring arterial blood oxygen saturation based on dual-color light arterial blood vessel images according to claim 3, characterized in that: In the step 2.3), the calculation method of the binarization process is: Among them, f ij is the binarized value of the pixel in the i-th row and j-th column of the image sequence; α is the curvature mean binarization coefficient, and its value range is [0, 1].

5. The method for measuring arterial blood oxygen saturation based on dual-color light arterial blood vessel images according to claim 4, characterized in that: The value of the curvature mean binarization coefficient α is 0.

5.

6. The method for measuring arterial blood oxygen saturation based on dual-color light arterial blood vessel images according to claim 4, characterized in that: In the step 3), the expansion optical path and the contraction optical path at the current wavelength are calculated based on the binary effective areas of the two sets of image digital signals after the enhancement processing and the binary processing.

7. The method for measuring arterial blood oxygen saturation based on dual-color light arterial blood vessel images according to claim 6, characterized in that: The specific calculation formula for calculating the expansion optical path and the contraction optical path at the current wavelength based on the binary effective area of ​​the two sets of image digital signals after enhancement processing and binary processing is: S max =max{S1,S2,S3,...,S A } (10) S min =min{S1, S2, S3,..., S A } (11) L max =S max (13) L min =S min (16) In the formula, S m is the effective area of ​​the arterial blood vessel binarization of the mth image sequence; is the binary value of the pixel in the i-th row and j-th column of the m-th image sequence; S max is the binary effective area when the artery is dilated; S min is the binary effective area when the artery contracts; A is the number of image digital signals acquired at the current wavelength; L max L is the optical path length when the artery is dilated; min It is the light path length when the artery contracts.

8. The method for measuring arterial blood oxygen saturation based on dual-color light arterial blood vessel images according to claim 7, characterized in that: The specific steps of step 4) calculating the arterial blood oxygen saturation according to the expansion optical path and contraction optical path of the arterial blood vessel include: 4.1) Calculate the intensity of the transmitted light when the artery is dilated. The calculation formula is as follows: In the formula, I A is the intensity of the transmitted light when the artery is dilated; I0 is the intensity of the incident light when the artery is dilated; γ is the absorption coefficient of the non-pulsating components in the tissue and venous blood; ε HbO2 C is the absorption coefficient of oxygenated hemoglobin in arterial blood vessels; HbO2 is the concentration of oxygenated hemoglobin in arteries; Hb C is the absorption coefficient of reduced hemoglobin in arterial blood vessels; Hb To indicate the concentration of reduced hemoglobin in arterial blood vessels; is the gray value of the pixel in the i-th row and j-th column of the artery dilation image sequence; is the binary value of the pixel in the i-th row and j-th column of the artery dilation image sequence; r1 is the image row number of the artery dilation image sequence; c1 is the image column number of the artery dilation image sequence; 4.2) Calculate the intensity of the transmitted light when the artery contracts. The calculation formula is as follows: In the formula, I B is the intensity of the transmitted light when the artery contracts; I0' is the intensity of the incident light when the artery contracts; is the gray value of the pixel in the i-th row and j-th column of the arterial contraction image sequence; is the binary value of the pixel in the i-th row and j-th column of the arterial contraction image sequence; r2 is the number of image rows in the arterial contraction image sequence; c2 is the number of image columns in the arterial contraction image sequence; 4.3) Integrate and take logarithms of formulas (12) to (14) to obtain formula (18): 4.4) Integrate and logarithm formulas (15) to (17) to obtain formula (19): 4.5) Integrate formulas (18) to (19) to obtain formulas (20) and (21), which are used to calculate the quantitative parameters of the pulsation information of the arterial blood vessels: C HbO2 e HbO2 +C Hb e Hb =R (20) In the formula, R is the quantitative parameter of the pulsation information of the arterial blood vessels. Substitute the two sets of image digital signals obtained when the wavelength is λ1 and λ2 into formula (21) respectively, and calculate the quantitative parameters of the pulsation information of the arterial blood vessels when the incident light wavelength is λ1 The quantitative parameters of the pulsation information of the arterial blood vessels when the incident light wavelength is λ2 4.6) According to formula (20), the calculation formula for the quantitative parameters of the pulsation information of the arterial blood vessels under the illumination of two wavelengths λ1 and λ2 is obtained: In the formula, is the absorption coefficient of oxygenated hemoglobin in the arterial blood vessel when the wavelength of incident light is λ1; is the absorption coefficient of reduced hemoglobin in the arterial blood vessel when the incident light wavelength is λ1; is the absorption coefficient of oxygenated hemoglobin in the artery when the wavelength of incident light is λ2; is the absorption coefficient of reduced hemoglobin in the arterial blood vessel when the incident light wavelength is λ2; 4.7) Integrate formulas (22) to (23) to obtain formula (24): 4.8) The calculation formula of arterial blood oxygen saturation is obtained according to formula (24), and the arterial blood oxygen saturation is calculated. The calculation formula of arterial blood oxygen saturation is: In the formula, SpO2 is the arterial oxygen saturation; C HbO2 is the concentration of oxygenated hemoglobin in the arteries; C Hb It is the concentration of reduced hemoglobin in arteries.

9. The method for measuring arterial blood oxygen saturation based on dual-color light arterial blood vessel images according to claim 1, characterized in that: In the step 1), a camera device is used to collect light signals after light transmission at two different wavelengths. The frame rate of the camera device is 60 frames / s. Under the irradiation of each wavelength of the light beam, the target part is placed for at least 1 second, and at least 60 digital image signals of the current wavelength are obtained.

10. An arterial blood oxygen saturation measurement device based on dual-color light arterial blood vessel images, characterized in that: It includes: The acquisition module irradiates the target part with light beams of wavelengths λ1 and λ2 respectively, collects the light signals after light transmission at two different wavelengths, and converts the light signals into image digital signals; An image processing module is used to perform image enhancement processing and binarization processing on the two sets of image digital signals obtained; An optical path calculation module is used to calculate the expansion optical path and contraction optical path of the arterial blood vessels generated by the pulsation of the arterial blood vessels at wavelengths of λ1 and λ2 respectively according to two sets of enhanced and binarized image digital signals; The arterial blood oxygen saturation calculation module is used to calculate the arterial blood oxygen saturation according to the expansion optical path and contraction optical path of the arterial blood vessels under two wavelengths, so as to reflect the blood oxygen content of the human body.

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