Method, apparatus, storage medium, and system for evaluating the reliability of physiological optical signals

Abstract

The present disclosure provides a method, apparatus, storage medium, and system for evaluating the reliability of physiological optical signals. The method includes: obtaining a plurality of physiological optical signal sequences of the same signal channel, where each physiological optical signal sequence corresponds to a wavelength and includes a plurality of physiological optical signals with the corresponding wavelength arranged in the order of acquisition time; performing at least one of correlation evaluation and quality evaluation on the plurality of physiological optical signal sequences; obtaining the reliability information of the signal channel based on the evaluation results of at least one of the correlation evaluation and the quality evaluation, where the correlation evaluation includes: evaluating the correlation between two physiological optical signal sequences in the plurality of physiological optical signal sequences, where the reliability is positively correlated with the correlation, and the quality evaluation includes: evaluating the signal-to-noise ratio quality of each physiological optical signal sequence in the plurality of physiological optical signal sequences, where the reliability is positively correlated with the signal-to-noise ratio quality.

Description

Technical Field

[0001] The present disclosure generally relates to the technical field of medical signal processing, and more specifically, to a method, apparatus, storage medium, and system for evaluating the credibility of physiological optical signals. Background Art

[0002] Near-infrared spectroscopy functional imaging technology has been used in the academic community for many years, but its inherent limitations cannot be ignored: like electroencephalogram signals, near-infrared signals are affected by various noises and interferences during the acquisition process, resulting in a significantly lower signal-to-noise ratio than MRI (Magnetic Resonance Imaging).

[0003] Currently, the preprocessing of near-infrared functional imaging signals focuses on shallow noise processing such as detrending and drift removal of the signals, without caring whether the instrument has truly captured the hemodynamic feedback signals, resulting in a large amount of invalid data in the signal data as the research basis, weakening the accuracy and reliability of related research. Summary of the Invention

[0004] The present disclosure provides a method, apparatus, storage medium, and system for evaluating the credibility of physiological optical signals to solve at least one of the above problems.

[0005] According to an aspect of the present disclosure, there is provided a method for evaluating the credibility of physiological optical signals, including: obtaining a plurality of physiological optical signal sequences of the same signal channel, where each physiological optical signal sequence corresponds to a wavelength and includes a plurality of physiological optical signals with the corresponding wavelength arranged in the order of acquisition time; performing at least one of correlation evaluation and quality evaluation on the plurality of physiological optical signal sequences; and obtaining the credibility information of the signal channel based on the evaluation results of at least one of the correlation evaluation and the quality evaluation, where the correlation evaluation includes: evaluating the correlation between two physiological optical signal sequences in the plurality of physiological optical signal sequences, where the credibility is positively correlated with the correlation, and the quality evaluation includes: evaluating the signal-to-noise ratio quality of each physiological optical signal sequence in the plurality of physiological optical signal sequences, where the credibility is positively correlated with the signal-to-noise ratio quality.

[0006] Optionally, the evaluating the correlation between every two physiological optical signal sequences among the multiple physiological optical signal sequences includes: based on the multiple wavelengths corresponding to the multiple physiological optical signal sequences, forming a wavelength pair by combining two different wavelengths, to obtain a plurality of wavelength pairs, wherein each wavelength among the multiple wavelengths has a corresponding wavelength pair; for each wavelength pair, calculating a correlation metric between the physiological optical signal sequences of the two different wavelengths; counting the correlation metrics of the plurality of wavelength pairs to obtain a correlation index of the signal channel; and determining the correlation according to the correlation index.

[0007] Optionally, the forming a wavelength pair by combining two different wavelengths based on the multiple wavelengths corresponding to the multiple physiological optical signal sequences to obtain a plurality of wavelength pairs includes: determining one wavelength from the multiple wavelengths corresponding to the multiple physiological optical signal sequences as a reference wavelength; and pairing the reference wavelength with each of the other wavelengths among the multiple wavelengths to obtain the plurality of wavelength pairs.

[0008] Optionally, the correlation metric includes the Pearson correlation coefficient.

[0009] Optionally, the determining the correlation according to the correlation index includes: determining that the correlation is relevant when the correlation index is greater than a correlation threshold, and otherwise determining that the correlation is irrelevant.

[0010] Optionally, the evaluating the signal-to-noise ratio quality of each physiological optical signal sequence among the multiple physiological optical signal sequences includes: respectively calculating the power spectral density of each physiological optical signal sequence among the multiple physiological optical signal sequences; and determining the signal-to-noise ratio quality according to the power spectral density of each physiological optical signal sequence among the multiple physiological optical signal sequences.

[0011] Optionally, the determining the signal-to-noise ratio quality according to the power spectral density of each physiological optical signal sequence among the multiple physiological optical signal sequences includes: determining that the signal-to-noise ratio quality passes when the peak value of the power spectral density of each physiological optical signal sequence among the multiple physiological optical signal sequences is greater than a peak value threshold, and otherwise determining that the signal-to-noise ratio quality fails.

[0012] Optionally, the respectively calculating the power spectral density of each physiological optical signal sequence among the multiple physiological optical signal sequences includes: respectively performing filtering processing on each physiological optical signal sequence among the multiple physiological optical signal sequences to obtain a plurality of physiological optical signal sequences within a specified frequency range; and respectively performing power spectral density calculation processing on each physiological optical signal sequence among the plurality of physiological optical signal sequences within the specified frequency range to obtain the power spectral density of each physiological optical signal sequence among the multiple physiological optical signal sequences.

[0013] Optionally, the obtaining of multiple physiological optical signal sequences of the same signal channel includes: obtaining multiple physiological light intensity signal sequences of the same signal channel, where each physiological light intensity signal sequence corresponds to a wavelength and includes multiple physiological light intensity signals with the corresponding wavelength arranged in the order of acquisition time; for each physiological light intensity signal sequence, using the physiological light intensity signal at the reference time as the reference signal, performing optical density calculation processing on the physiological light intensity signal sequence to obtain an optical density signal sequence as the physiological optical signal sequence.

[0014] According to another aspect of the present disclosure, there is provided a physiological optical signal credibility evaluation device, including: an obtaining unit configured to obtain multiple physiological optical signal sequences of the same signal channel, where each physiological optical signal sequence corresponds to a wavelength and includes multiple physiological optical signals with the corresponding wavelength arranged in the order of acquisition time; an evaluation unit configured to perform at least one of a correlation evaluation and a quality evaluation on the multiple physiological optical signal sequences; a determination unit configured to obtain the credibility information of the signal channel based on the evaluation results of at least one of the correlation evaluation and the quality evaluation, where the correlation evaluation includes: evaluating the correlation between two physiological optical signal sequences among the multiple physiological optical signal sequences, where the credibility is positively correlated with the correlation, and the quality evaluation includes: evaluating the signal-to-noise ratio quality of each physiological optical signal sequence among the multiple physiological optical signal sequences, where the credibility is positively correlated with the signal-to-noise ratio quality.

[0015] Optionally, the operation of the evaluation unit for evaluating the correlation between two physiological optical signal sequences among the multiple physiological optical signal sequences includes: based on the multiple wavelengths corresponding to the multiple physiological optical signal sequences, forming a wavelength pair by combining two different wavelengths to obtain multiple wavelength pairs, where each wavelength among the multiple wavelengths has a corresponding wavelength pair; for each wavelength pair, calculating the correlation metric of the physiological optical signal sequences of the two different wavelengths; statistically analyzing the correlation metrics of the multiple wavelength pairs to obtain the correlation index of the signal channel; and determining the correlation according to the correlation index.

[0016] Optionally, the operation of the evaluation unit for forming a wavelength pair by combining two different wavelengths based on the multiple wavelengths corresponding to the multiple physiological optical signal sequences to obtain multiple wavelength pairs includes: determining one wavelength from the multiple wavelengths corresponding to the multiple physiological optical signal sequences as the reference wavelength; and pairing the reference wavelength with each of the other wavelengths among the multiple wavelengths to obtain the multiple wavelength pairs.

[0017] Optionally, the correlation metric includes the Pearson correlation coefficient.

[0018] Optionally, the operation of determining the correlation by the evaluation unit according to the correlation index includes: when the correlation index is greater than the correlation threshold, determining that the correlation is relevant; otherwise, determining that the correlation is irrelevant.

[0019] Optionally, the operation of evaluating the signal-to-noise ratio quality of each physiological optical signal sequence among the multiple physiological optical signal sequences by the evaluation unit includes: calculating the power spectral density of each physiological optical signal sequence among the multiple physiological optical signal sequences respectively; determining the signal-to-noise ratio quality according to the power spectral density of each physiological optical signal sequence among the multiple physiological optical signal sequences.

[0020] Optionally, the operation of determining the signal-to-noise ratio quality by the evaluation unit according to the power spectral density of each physiological optical signal sequence among the multiple physiological optical signal sequences includes: when the peak value of the power spectral density of each physiological optical signal sequence among the multiple physiological optical signal sequences is greater than the peak threshold, determining that the signal-to-noise ratio quality passes; otherwise, determining that the signal-to-noise ratio quality fails.

[0021] Optionally, the operation of calculating the power spectral density of each physiological optical signal sequence among the multiple physiological optical signal sequences by the evaluation unit respectively includes: performing filtering processing on each physiological optical signal sequence among the multiple physiological optical signal sequences respectively to obtain multiple physiological optical signal sequences within a specified frequency range; performing power spectral density calculation processing on each physiological optical signal sequence among the multiple physiological optical signal sequences within the specified frequency range respectively to obtain the power spectral density of each physiological optical signal sequence among the multiple physiological optical signal sequences.

[0022] Optionally, the obtaining unit is further configured to: obtain multiple physiological light intensity signal sequences of the same signal channel, where each physiological light intensity signal sequence corresponds to a wavelength and includes multiple physiological light intensity signals with the corresponding wavelength arranged in the order of collection time; for each physiological light intensity signal sequence, taking the physiological light intensity signal at the reference moment as the reference signal, performing optical density calculation processing on the physiological light intensity signal sequence to obtain an optical density signal sequence as the physiological optical signal sequence.

[0023] According to another aspect of the present disclosure, there is provided a computer-readable storage medium storing instructions, wherein when the instructions are run by at least one computing device, the at least one computing device is caused to execute the physiological optical signal credibility evaluation method as described above.

[0024] According to another aspect of the present disclosure, there is provided a system including at least one computing device and at least one storage device storing instructions, wherein, when the instructions are executed by the at least one computing device, the at least one computing device is caused to execute the physiological optical signal credibility evaluation method as described above.

[0025] According to another aspect of the present disclosure, there is provided a computer program product including instructions, wherein, when the instructions are executed by at least one computing device, the at least one computing device is caused to execute the physiological optical signal credibility evaluation method as described above.

[0026] For the physiological optical signal credibility evaluation method, device, storage medium, and system according to the exemplary embodiments of the present disclosure, by performing at least one evaluation on physiological optical signal sequences of multiple wavelengths in the same signal channel, the correlation between different wavelength signals in the collected signals and / or the signal-to-noise ratio quality of each wavelength signal can be evaluated, thereby reflecting the overall credibility of the collected signals, helping to eliminate invalid signal data with low credibility during relevant research, reducing the influence of interference signals, and improving the accuracy and reliability of relevant research.

[0027] Additional aspects and / or advantages of the general concept of the present disclosure will be set forth in part in the description that follows, and in part will be obvious from the description, or may be learned by practice of the general concept of the present disclosure. Brief Description of the Drawings

[0028] These and / or other aspects and advantages of the present disclosure will become apparent and be more readily understood from the following description of the embodiments when taken in conjunction with the accompanying drawings.

[0029] Figure 1 is a flowchart showing a physiological optical signal credibility evaluation method according to an exemplary embodiment of the present disclosure.

[0030] Figure 2 is a schematic diagram showing the software and hardware connection relationship of a physiological optical signal credibility system according to a specific embodiment of the present disclosure.

[0031] Figure 3 is a schematic diagram showing a power spectral density curve according to a specific embodiment of the present disclosure.

[0032] Figure 4 is a block diagram showing a physiological optical signal credibility evaluation device according to an exemplary embodiment of the present disclosure. Detailed Description of the Embodiments

[0033] The following description with reference to the accompanying drawings is provided to assist in a comprehensive understanding of embodiments of the present invention defined by the claims and their equivalents. Various specific details are included to facilitate understanding, but these details are only considered exemplary. Thus, those of ordinary skill in the art will recognize that various changes and modifications can be made to the embodiments described herein without departing from the scope and spirit of the present invention. In addition, descriptions of well-known functions and structures are omitted for clarity and conciseness.

[0034] It should be noted here that "at least one of several items" in the present disclosure all represents the inclusion of three parallel cases: "any one of the several items", "a combination of any multiple of the several items", and "all of the several items". For example, "including at least one of A and B" includes the following three parallel cases: (1) including A; (2) including B; (3) including A and B. Another example, "performing at least one of step one and step two" means the following three parallel cases: (1) performing step one; (2) performing step two; (3) performing step one and step two.

[0035] The following refers to Figures 1 to 3 A physiological optical signal credibility evaluation method, apparatus, storage medium, and system according to an exemplary embodiment of the present disclosure will be described in detail.

[0036] Figure 1 is a flowchart showing a physiological optical signal credibility evaluation method according to an exemplary embodiment of the present disclosure. The physiological optical signal credibility evaluation method according to an exemplary embodiment of the present disclosure can be implemented in a computing device with sufficient computing power.

[0037] Referring to Figure 1 , in step S101, a plurality of physiological optical signal sequences of the same signal channel are acquired.

[0038] Each physiological optical signal sequence corresponds to a wavelength and includes a plurality of physiological optical signals with the corresponding wavelength arranged in the order of acquisition time. Specifically, taking the acquisition of near-infrared brain imaging signals as an example, near-infrared spectroscopy (NIRS) is a spectroscopic analysis technique that can measure the absorption, reflection, or transmission characteristics of substances in the near-infrared wavelength range (usually 600nm - 900nm). In the field of mental psychology, by using NIRS to irradiate the prefrontal cortex of the brain and observing the concentration changes of oxyhemoglobin and deoxyhemoglobin in the prefrontal lobe during the verbal fluency task (VFT), near-infrared brain imaging data can be obtained, which can reflect the emotional characteristics of the subject and the ability to regulate emotions. The acquisition of near-infrared brain imaging signals requires corresponding equipment, such as but not limited to a prefrontal headgear, a probe connecting wire, and a near-infrared brain imaging instrument. The headgear is provided with a plurality of optical probes, including a light source probe (for emitting near-infrared light) and a detector probe (for receiving the light reflected or scattered from brain tissues). These optical probes are distributed on the headgear and arranged at a certain spacing. The near-infrared brain imaging instrument is connected to the optical probes through the probe connecting wire. The control module of the near-infrared brain imaging instrument controls the light source probe to emit near-infrared light of a specific wavelength. After the near-infrared light is scattered and absorbed by brain tissues, the reflected light signals are received by the detector probe, and these signals are transmitted to the data acquisition module of the near-infrared brain imaging instrument through the probe connecting wire, and finally, after being processed and analyzed, they are used to reflect the blood oxygen changes in the cerebral cortex. For an optical probe, the optical signal measurement path from a light source probe to a detector probe is called a signal channel. In other words, a signal channel is composed of a light source probe and a detector probe. For example, if the headgear is provided with 3 light source probes and 4 detector probes, theoretically 12 signal channels can be formed, and these channels can cover different regions of the brain and be used to simultaneously measure the blood oxygen changes at multiple positions. For each signal channel, signal acquisition is usually performed at a set sampling frequency, and multiple signals of different wavelengths can be acquired by adopting specific techniques (such as but not limited to frequency division multiplexing, time division multiplexing, continuous wave method, phase-locked photon counting, etc. These techniques are all mature techniques in this field and will not be elaborated here). Group these signals according to the wavelength. The signals acquired at each moment under the same wavelength form a group, and arrange this group of signals in the order of acquisition time into a sequence, and a near-infrared brain imaging signal sequence is obtained, which corresponds to a physiological optical signal sequence here. It should be understood that in addition to near-infrared brain imaging signals, other physiological signals acquired using optical principles can also be used as the physiological optical signals in this disclosure, and the credibility evaluation method of the physiological optical signals in the embodiments of this disclosure is used to evaluate their credibility.

[0039] In some embodiments, optionally, step S101 includes: obtaining a plurality of physiological light intensity signal sequences of the same signal channel, where each physiological light intensity signal sequence corresponds to a wavelength and includes a plurality of physiological light intensity signals with the corresponding wavelength arranged in the order of acquisition time; for each physiological light intensity signal sequence, using the physiological light intensity signal at the reference time as the reference signal, performing optical density calculation processing on the physiological light intensity signal sequence to obtain an optical density signal sequence as the physiological optical signal sequence. Here, the physiological light intensity signal is the signal directly collected by the signal acquisition device (such as, including but not limited to, near-infrared brain imaging instrument), and the optical density signal is a dimensionless quantity obtained based on the physiological light intensity signal. It is a logarithmic value, representing the attenuation degree of light when passing through the material, and can be used to characterize the light absorption ability of the material. By using the optical density signal sequence as the physiological light intensity signal sequence, the concentration change of hemoglobin can be calculated more accurately, so as to reflect the physiological activities of the brain. As an example, the starting time of each physiological light intensity signal sequence can be used as the reference time, that is, the first physiological light intensity signal in the sequence is used as the reference signal. Of course, other times can also be selected as the reference time, and the present disclosure does not limit this.

[0040] Specifically, the optical density signal sequence can be calculated based on the Modified Beer-Lambert Law. The Modified Beer-Lambert Law is a formula that describes the relationship between the absorption amount of light passing through a substance and various factors. The original Beer's Law states the linear relationship between the absorbance of light (or the logarithm of the transmittance) and its concentration and path length when light propagates in a uniform, non-scattering medium. The Modified Beer-Lambert Law is usually used to describe complex situations in practical applications, such as considering scattering effects, refraction, and reflection under non-ideal conditions (such as the presence of suspended particles in the solution or the solvent itself having color). When calculating the optical density signal sequence, specifically, for a physiological light intensity signal sequence, calculate the ratio of each physiological light intensity signal to the reference signal as the transmittance, and then calculate the logarithm of the transmittance to obtain the optical density signal. These optical density signals are arranged in the order of the corresponding physiological light intensity signals (i.e., the order of acquisition time) to form an optical density signal sequence.

[0041] In some other embodiments, optionally, step S101 includes: obtaining a plurality of physiological light intensity signal sequences of the same signal channel as the physiological optical signal sequence.

[0042] In step S102, perform at least one of correlation evaluation and quality evaluation on the plurality of physiological optical signal sequences.

[0043] Specifically, the correlation evaluation includes: evaluating the correlation between pairwise physiological optical signal sequences among multiple physiological optical signal sequences, where the credibility is positively correlated with the correlation. The quality evaluation includes: evaluating the signal-to-noise ratio quality of each physiological optical signal sequence among multiple physiological optical signal sequences, where the credibility is positively correlated with the signal-to-noise ratio quality.

[0044] In step S103, based on the evaluation results of at least one of the correlation evaluation and the quality evaluation, the credibility information of the signal channel is obtained.

[0045] As an example, all the evaluation results can be directly aggregated as the credibility information, or the evaluation results can be further processed to obtain the credibility information. The present disclosure does not limit this.

[0046] According to the physiological optical signal credibility evaluation method of the exemplary embodiment of the present disclosure, by performing at least one of the above evaluations on the physiological optical signal sequences of multiple wavelengths in the same signal channel, the correlation between different wavelength signals and / or the signal-to-noise ratio quality of each wavelength signal in the collected signal can be evaluated, thereby reflecting the overall credibility of the collected signal, which helps to eliminate invalid signal data with low credibility in relevant research, reduces the influence of interference signals, and improves the accuracy and reliability of relevant research.

[0047] As an example, when processing physiological optical signals to assist medical diagnosis or research, it is usually necessary to preprocess the signals first, such as including but not limited to detrending and removing drift. The physiological optical signal credibility evaluation method according to the exemplary embodiment of the present disclosure can be executed before preprocessing the physiological optical signals, that is, there is no need to preprocess physiological optical signals with low credibility, which can effectively reduce the unnecessary preprocessing calculation amount and improve the subsequent data processing efficiency. Of course, in actual implementation, the timing of executing this method can also be determined according to specific requirements. The present disclosure does not limit this.

[0048] It should be understood that the acquisition of physiological optical signals often lasts for a period of time. For example, for near-infrared brain imaging signals, signals will be continuously acquired during the process of the subject performing a speech process task. Therefore, according to the physiological optical signal credibility evaluation method of the exemplary embodiment of the present disclosure, it can be executed once every other period of time during the signal acquisition process, that is, the credibility of the latest acquired signals or all the signals acquired so far is evaluated every other period of time, or it can also be executed after all the signals are acquired. The present disclosure does not limit this.

[0049] Next, the correlation evaluation will be introduced.

[0050] Optionally, the correlation between each pair of physiological optical signal sequences among multiple physiological optical signal sequences is evaluated, including: based on multiple wavelengths corresponding to the multiple physiological optical signal sequences, combining two different wavelengths into a wavelength pair to obtain multiple wavelength pairs, where each wavelength among the multiple wavelengths has a corresponding wavelength pair; for each wavelength pair, calculating the correlation metric of the physiological optical signal sequences of the two different wavelengths; counting the correlation metrics of the multiple wavelength pairs to obtain the correlation index of the signal channel; and determining the correlation according to the correlation index. Considering that if the collected physiological optical signals are valid, then there should be a high correlation between the signal sequences of different wavelengths in the same signal channel. Based on this, the present disclosure calculates and counts the signal correlation metrics between pairwise wavelengths of the physiological optical signal sequences of different wavelengths in the same signal channel to obtain the correlation index of the signal channel, and can quantitatively reflect whether the physiological optical signals collected by the signal channel as a whole are valid by means of the correlation degree between each wavelength, realizing an objective evaluation of the credibility of the physiological optical signals collected by a single signal channel. In addition, by first determining multiple wavelength pairs and then calculating the correlation metric for the two wavelengths in each wavelength pair, the reliability of the calculation process can be ensured and the accuracy of the evaluation can be improved.

[0051] Regarding how to obtain multiple wavelength pairs, optionally, this step includes: determining one wavelength from the multiple wavelengths corresponding to the multiple physiological optical signal sequences as the reference wavelength; pairing the reference wavelength with each of the multiple wavelengths other than the reference wavelength respectively to obtain multiple wavelength pairs. By combining one reference wavelength with other wavelengths into wavelength pairs respectively, that is, forming (N - 1) wavelength pairs when there are N wavelengths in total, each wavelength can be indirectly paired with other wavelengths through the reference wavelength, thus not only realizing the evaluation of the correlation of the signal sequences of any two wavelengths, but also forming as few wavelength pairs as possible, reducing the calculation amount and improving the calculation efficiency. As an example, the reference wavelength can be randomly selected from the multiple wavelengths, or a specific wavelength can be selected, such as the minimum wavelength, and the present disclosure does not limit this. Of course, other reasonable methods can also be used to obtain multiple wavelength pairs, such as including but not limited to pairing each wavelength with every other wavelength, obtaining wavelength pairs in the case of N wavelengths in total to achieve full pairing, or making each wavelength only participate in one wavelength pair, but allowing one wavelength to participate in two wavelength pairs when the total number of wavelengths is odd, obtaining N / 2 wavelength pairs when there are N wavelengths in total and N is even, and obtaining (N + 1) / 2 wavelength pairs when there are N wavelengths and N is odd, so as to minimize the number of wavelength pairs and reduce the calculation amount.

[0052] Regarding the correlation metric, optionally, the correlation metric includes the Pearson correlation coefficient. The Pearson correlation coefficient is a statistical method used to measure the strength and direction of the linear relationship between two variables, named after the British biostatistician Karl Pearson. The Pearson correlation coefficient is obtained by calculating the standardized covariance of two variables and their respective standard deviations. By using the Pearson correlation coefficient, an efficient quantification of the correlation between the signal sequences of two wavelengths is achieved. Of course, other correlation metrics may also be adopted in the embodiments of the present disclosure, such as, but not limited to, cosine similarity and Euclidean distance.

[0053] Regarding how to statistically calculate the correlation metrics of multiple wavelength pairs, optionally, statistical values such as the average value, mode, median, and specified quantiles of the correlation metrics of multiple wavelength pairs can be calculated, and the present disclosure does not limit this.

[0054] Regarding how to determine the correlation based on the correlation index, optionally, this step includes: when the correlation index is greater than the correlation threshold, determining that the correlation is relevant; otherwise, determining that the correlation is irrelevant. By setting the correlation threshold as the reference value of the correlation index indicating sufficient correlation, a qualitative evaluation based on quantitative evaluation can be conveniently achieved, facilitating an intuitive display of the evaluation results. It should be understood that the correlation threshold can be determined through theoretical analysis and experiments, and the larger its value, the stricter the evaluation criteria for correlation. The present disclosure does not limit the specific value and specific determination method of the correlation threshold.

[0055] Next, the signal-to-noise ratio quality assessment will be introduced.

[0056] Optionally, the signal-to-noise ratio quality of each physiological optical signal sequence among multiple physiological optical signal sequences is evaluated, including: calculating the power spectral density of each physiological optical signal sequence among the multiple physiological optical signal sequences respectively; determining the signal-to-noise ratio quality according to the power spectral density of each physiological optical signal sequence among the multiple physiological optical signal sequences. The power spectral density (PSD for short) is a function that describes the power distribution of a signal in the frequency domain. It represents the average power within a unit frequency band and is usually denoted as S(f) or S(ω), where f is the frequency and ω is the angular frequency. It describes the characteristics of how the energy of a signal is distributed with frequency and provides an important tool for the conversion from the time domain to the frequency domain. By understanding the power spectral density of a signal, it is possible to better analyze and design systems, filters, and conduct applications such as communication. Although the magnitude of the power spectral density does not directly represent the magnitude of the signal-to-noise ratio (SNR), there is a close relationship with the signal-to-noise ratio and it is easier to calculate compared to the signal-to-noise ratio. By determining the signal-to-noise ratio quality based on the power spectral density, compared with directly calculating the signal-to-noise ratio, it can meet the signal quality evaluation requirements with less computational effort and improve the evaluation efficiency. Of course, in other embodiments, other reasonable forms can also be used to evaluate the signal-to-noise ratio quality of the signal, such as including but not limited to directly calculating the signal-to-noise ratio.

[0057] Regarding the calculation of the power spectral density, optionally, this step includes: performing filtering processing on each physiological optical signal sequence among the multiple physiological optical signal sequences respectively to obtain multiple physiological optical signal sequences within a specified frequency range; performing power spectral density calculation processing on each physiological optical signal sequence among the multiple physiological optical signal sequences within the specified frequency range to obtain the power spectral density of each physiological optical signal sequence among the multiple physiological optical signal sequences. By first performing filtering processing on the time-domain signals (i.e., multiple physiological optical signal sequences) for the specified frequency range and then calculating the power spectral density of the filtered signal sequences, it is possible to only consider the signal components within the specified frequency range when calculating the power spectral density, making the calculation result more accurately reflect the power distribution within the specified frequency range. Of course, filtering processing may not be performed, and the power spectral density calculation processing can be directly performed on each obtained physiological optical signal sequence. It is also possible to further intercept the results within the specified frequency range of the power spectral density obtained thereby (whose accuracy is lower than the embodiment of filtering first described above), which is also an implementation manner of the present disclosure. The power spectral density calculation processing belongs to a mature technology in the art and will not be elaborated here. It should be understood that the specified frequency range can be set as needed, such as including but not limited to 0.1 Hz to 3 Hz, and the present disclosure does not limit this.

[0058] Regarding how to determine the signal-to-noise ratio quality, optionally, this step includes: when the peak value of the power spectral density of each physiological optical signal sequence among multiple physiological optical signal sequences is greater than the peak threshold, determining that the signal-to-noise ratio quality passes; otherwise, determining that the signal-to-noise ratio quality fails. On the one hand, by setting the peak threshold as the reference value of the power spectral density peak indicating sufficient signal-to-noise ratio quality of a single physiological optical signal sequence, it is possible to relatively reliably evaluate the signal-to-noise ratio quality of the signal using the power spectral density without calculating the signal-to-noise ratio, and it is convenient to implement qualitative evaluation based on quantitative evaluation, facilitating the intuitive display of the evaluation results. On the other hand, by making the peak values of the power spectral densities of multiple physiological optical signals large enough as the condition for evaluating that the signal-to-noise ratio quality of the overall signal passes, it is not only convenient to summarize the quality evaluation results of signal sequences of different wavelengths but also fully ensures the reliability of the overall quality evaluation results. It should be understood that the peak threshold can be determined through theoretical analysis and experiments. The larger its value, the stricter the evaluation standard for the signal-to-noise ratio quality. The present disclosure does not limit the specific value and specific determination method of the peak threshold. It should also be understood that in actual implementation, for the power spectral density of each physiological optical signal sequence, the peak value can be calculated and then compared with the peak threshold, or the peak value may not be calculated. As long as it is determined that there is a value greater than the peak threshold in the power spectral density, it is considered that the peak value must also be greater than the peak threshold. These are all implementation manners of the present disclosure. Of course, other reasonable embodiments other than that the peak values of each power spectral density are greater than the peak threshold can also be adopted to determine the signal-to-noise ratio quality, and the present disclosure does not limit this.

[0059] Next, a method for evaluating the credibility of physiological optical signals in a specific embodiment of the present disclosure will be introduced.

[0060] This specific embodiment is used to evaluate the credibility of near-infrared brain imaging signals. During the acquisition process of this signal, it will be affected by various noises and interferences, such as the following 5 kinds of influences.

[0061] (1) The sensor is irradiated by external environmental light or interfered by a magnetic field.

[0062] (2) The sensor is not in contact with the scalp.

[0063] (3) Even if the sensor is in good contact with the scalp, the adjacent infrared laser is blocked by hair, resulting in a weak detected signal or no detected signal.

[0064] (4) There is no observable blood vessel distribution at the depth of the detection position pointed by the sensor.

[0065] (5) The sensor optical fiber or laser optical fiber is damaged, aged, or the optical fiber is exposed, resulting in signals without physiological significance.

[0066] This specific embodiment can identify signal channels with the above problems (1) to (5) before preprocessing the data, and output whether a standard reflecting hemodynamic characteristics is achieved for the signal channel, thereby reducing the influence of interference signals.

[0067] This specific embodiment is implemented based on a physiological optical signal credibility system. Figure 2 The connection relationship between the hardware and software of the system is shown. As Figure 2 shown, the near-infrared brain imaging instrument 20 can collect the brain function signals of the subject and output a sequence of physiological optical intensity signals. This evaluation method obtains multiple physiological optical intensity signal sequences of the same signal channel from a data source (near-infrared brain imaging instrument 20) in a real-time or non-real-time manner, and obtains an evaluation result (credibility information) through a series of data processing. The evaluation includes correlation evaluation and quality evaluation. The execution order of the two evaluations is not limited, and they can be executed successively (for example, including but not limited to Figure 2 shown to perform correlation evaluation first and then quality evaluation), or they can be executed in parallel. The evaluation result is output to a screen 30. The operator can improve the quality of the research data by adjusting the sensor in real time or through the output of the system when analyzing the data afterwards in combination with the evaluation result displayed on the screen 30.

[0068] The process of a series of data processing is as follows.

[0069] First, the system receives the physiological optical intensity signal sequence from the near-infrared brain imaging instrument 20. Assume that the instrument has a total of C channels and contains N wavelengths of independent near-infrared light. Then the system receives a total of C×N signal sequences. The system first sets the first signal value in each sequence as the reference signal R of the sequence. Next, by calculating the modified Beer-Lambert law for each physiological optical intensity signal OI(t) in the sequence based on the reference signal, the corresponding optical density signal OD(t) is obtained, which is expressed by the formula:

[0070] OD(t) = log(OI(t) / R).

[0071] For the physiological optical intensity signal sequences OD of all wavelengths of the same signal channel, they are respectively denoted as ODλ1, ODλ2,...., ODλN.

[0072] Then, correlation evaluation is performed. Since the blood tissue in the human body shows a certain absorption law when absorbing near-infrared light, if the signals of all wavelengths successfully reflect the absorption, then the positive correlation between the signals of two wavelengths will be relatively high. Based on this, the Pearson correlation coefficient PC can be used to calculate all pairs of OD signals, and the correlation index E1 is obtained:

[0073] E1 = (1 / (N - 1)) × ∑PCλ(a,b).

[0074] Among them, N wavelengths form (N - 1) wavelength pairs. λ(a,b) represents a wavelength pair, and PCλ(a,b) represents the Pearson correlation coefficient of the OD signal sequences of two different wavelengths in this wavelength pair.

[0075] Set the correlation threshold T1. If E1 > T1, it is considered that the signal passes the correlation evaluation. The larger T1 is, the higher the strictness of passing the correlation evaluation. The correlation evaluation can effectively eliminate the signal interference caused by (3) and (5).

[0076] Next, quality assessment is carried out. The system will identify which OD signal sequences contain real physiological signals with a high signal-to-noise ratio by analyzing the distribution pattern and characteristic spikes of the power spectral density of the OD signal sequence of each wavelength. For each OD signal sequence, first perform filtering (retaining signals within 0.1 Hz to 3 Hz), then calculate the power spectral density, and finally analyze to obtain the signal-to-noise ratio quality E2.

[0077] Generally speaking, the power spectral density will present a spike at the main frequency components (as shown in Figure 3 ). If there is a spike in the power spectral density of each OD signal sequence that is higher than the peak threshold T2, that is, the peak is higher than the peak threshold T2, it is considered that the signal-to-noise ratio quality E2 passes, otherwise it is considered not to pass. In other words, as long as there is a peak in the power spectral density of an OD signal sequence that is less than or equal to the peak threshold T2, it is considered that the signal-to-noise ratio quality E2 does not pass.

[0078] In actual experiments, the larger the peak threshold T2 is, the higher the strictness of passing the quality assessment. The quality assessment can effectively eliminate the signal interference caused by (1), (2), and (4).

[0079] Finally, the system will display the pass / fail status of all signal channels on screen 30 using a list such as Table 1 below, and users can adjust their research strategies through the list.

[0080] Table 1 Credibility Information List

[0081]

[0082] This list can be updated in real time according to the data obtained in a time period. As an example, only the data of the latest time period needs to be processed and output during the update, that is, only the credibility of the physiological light intensity signals collected in the latest time period is evaluated, and the evaluated credibility information is output. It is also possible to update this list after all the data has been transmitted.

[0083] Figure 4It is a block diagram showing a physiological optical signal reliability evaluation device according to an exemplary embodiment of the present disclosure.

[0084] Referring to Figure 4 , the physiological optical signal reliability evaluation device 400 includes an acquisition unit 401, an evaluation unit 402, and a determination unit 403.

[0085] The acquisition unit 401 can acquire multiple physiological optical signal sequences of the same signal channel, where each physiological optical signal sequence corresponds to a wavelength and includes multiple physiological optical signals with the corresponding wavelength arranged in the order of acquisition time.

[0086] The evaluation unit 402 can perform at least one of a correlation evaluation and a quality evaluation on the multiple physiological optical signal sequences. The correlation evaluation includes: evaluating the correlation between every two physiological optical signal sequences among the multiple physiological optical signal sequences, where the reliability is positively correlated with the correlation. The quality evaluation includes: evaluating the signal-to-noise ratio quality of each physiological optical signal sequence among the multiple physiological optical signal sequences, where the reliability is positively correlated with the signal-to-noise ratio quality.

[0087] The determination unit 403 can obtain the reliability information of the signal channel based on the evaluation results of at least one of the correlation evaluation and the quality evaluation.

[0088] Optionally, the operation of the evaluation unit 402 for evaluating the correlation between every two physiological optical signal sequences among the multiple physiological optical signal sequences includes: based on the multiple wavelengths corresponding to the multiple physiological optical signal sequences, forming a wavelength pair by combining two different wavelengths to obtain multiple wavelength pairs, where each wavelength among the multiple wavelengths has a corresponding wavelength pair; for each wavelength pair, calculating the correlation metric of the physiological optical signal sequences of the two different wavelengths; statistically analyzing the correlation metrics of the multiple wavelength pairs to obtain the correlation index of the signal channel; and determining the correlation according to the correlation index.

[0089] Optionally, the operation of the evaluation unit 402 for forming a wavelength pair by combining two different wavelengths based on the multiple wavelengths corresponding to the multiple physiological optical signal sequences to obtain multiple wavelength pairs includes: determining one wavelength from the multiple wavelengths corresponding to the multiple physiological optical signal sequences as the reference wavelength; and pairing the reference wavelength with each of the other wavelengths among the multiple wavelengths respectively to obtain multiple wavelength pairs.

[0090] Optionally, the correlation metric includes the Pearson correlation coefficient.

[0091] Optionally, the operation of the evaluation unit 402 for determining the correlation according to the correlation index includes: when the correlation index is greater than the correlation threshold, determining the correlation as relevant; otherwise, determining the correlation as irrelevant.

[0092] Optionally, the operation of the evaluation unit 402 for evaluating the signal-to-noise ratio quality of each physiological optical signal sequence among multiple physiological optical signal sequences includes: calculating the power spectral density of each physiological optical signal sequence among the multiple physiological optical signal sequences respectively; determining the signal-to-noise ratio quality according to the power spectral density of each physiological optical signal sequence among the multiple physiological optical signal sequences.

[0093] Optionally, the operation of the evaluation unit 402 for determining the signal-to-noise ratio quality according to the power spectral density of each physiological optical signal sequence among the multiple physiological optical signal sequences includes: when the peak value of the power spectral density of each physiological optical signal sequence among the multiple physiological optical signal sequences is greater than the peak threshold, determining that the signal-to-noise ratio quality passes; otherwise, determining that the signal-to-noise ratio quality fails.

[0094] Optionally, the operation of the evaluation unit 402 for calculating the power spectral density of each physiological optical signal sequence among the multiple physiological optical signal sequences respectively includes: performing filtering processing on each physiological optical signal sequence among the multiple physiological optical signal sequences respectively to obtain multiple physiological optical signal sequences within a specified frequency range; performing power spectral density calculation processing on each physiological optical signal sequence among the multiple physiological optical signal sequences within the specified frequency range respectively to obtain the power spectral density of each physiological optical signal sequence among the multiple physiological optical signal sequences.

[0095] Optionally, the acquisition unit 401 may further: acquire multiple physiological light intensity signal sequences of the same signal channel, where each physiological light intensity signal sequence corresponds to a wavelength and includes multiple physiological light intensity signals with the corresponding wavelength arranged in the order of acquisition time; for each physiological light intensity signal sequence, using the physiological light intensity signal at the reference moment as the reference signal, performing optical density calculation processing on the physiological light intensity signal sequence to obtain an optical density signal sequence as the physiological optical signal sequence.

[0096] The above has been described with reference to Figures 1 to 4 a method and apparatus for evaluating the credibility of physiological optical signals according to an exemplary embodiment of the present disclosure.

[0097] Figure 4 Each unit in the physiological optical signal credibility evaluation apparatus shown can be configured as software, hardware, firmware, or any combination of the above for performing specific functions. For example, each unit can correspond to an application-specific integrated circuit, can also correspond to pure software code, and can also correspond to a module combining software and hardware. In addition, one or more functions implemented by each unit can also be uniformly executed by components in a physical entity device (such as a processor, a client, or a server, etc.).

[0098] In addition, with reference to Figure 1The described method for evaluating the credibility of physiological optical signals can be implemented by a program (or instructions) recorded on a computer-readable storage medium. For example, according to an exemplary embodiment of the present disclosure, a computer-readable storage medium storing instructions may be provided, wherein when the instructions are run by at least one computing device, the at least one computing device is caused to execute the method for evaluating the credibility of physiological optical signals according to the present disclosure.

[0099] The computer program in the above computer-readable storage medium can run in an environment deployed in computer devices such as clients, hosts, proxy devices, servers, etc. It should be noted that the computer program can also be used to execute additional steps other than the above steps or perform more specific processing when executing the above steps. The content of these additional steps and further processing has been mentioned in the description of the relevant methods with reference to Figure 1 and will not be repeated here to avoid redundancy.

[0100] It should be noted that each unit in the device for evaluating the credibility of physiological optical signals according to an exemplary embodiment of the present disclosure can completely rely on the running of the computer program to achieve the corresponding functions, that is, each unit corresponds to each step in the functional architecture of the computer program, so that the entire system is called through a dedicated software package (for example, a lib library) to achieve the corresponding functions.

[0101] On the other hand, Figure 4 each of the units shown can also be implemented by hardware, software, firmware, middleware, microcode, or any combination thereof. When implemented by software, firmware, middleware, or microcode, the program code or code segment for performing the corresponding operations can be stored in a computer-readable medium such as a storage medium, so that the processor can execute the corresponding operations by reading and running the corresponding program code or code segment.

[0102] For example, an exemplary embodiment of the present disclosure can also be implemented as a computing device, which includes a storage component and a processor. The storage component stores a set of computer-executable instructions. When the set of computer-executable instructions is executed by the processor, the method for evaluating the credibility of physiological optical signals according to an exemplary embodiment of the present disclosure is executed.

[0103] Specifically, the computing device can be deployed in a server or a client, or on a node device in a distributed network environment. In addition, the computing device can be a PC computer, a tablet device, a personal digital assistant, a smart phone, a web physiological optical signal credibility evaluation, or other devices capable of executing the above set of instructions.

[0104] Here, the computing device does not have to be a single computing device, but can also be any collection of devices or circuits that can execute the above instructions (or instruction sets) individually or jointly. The computing device can also be part of an integrated control system or system manager, or can be configured as a portable electronic device that interfaces with a local or remote device (e.g., via wireless transmission).

[0105] In the computing device, the processor can include a central processing unit (CPU), a graphics processing unit (GPU), a programmable logic device, a dedicated processor system, a microcontroller, or a microprocessor. By way of example and not limitation, the processor can also include an analog processor, a digital processor, a microprocessor, a multi-core processor, a processor array, a network processor, etc.

[0106] Certain operations described in the physiological optical signal credibility evaluation method according to an exemplary embodiment of the present disclosure can be implemented in software, certain operations can be implemented in hardware, and in addition, these operations can also be implemented in a combination of software and hardware.

[0107] The processor can run instructions or code stored in one of the storage components, where the storage component can also store data. The instructions and data can also be sent and received via a network interface device over a network, where the network interface device can use any known transmission protocol.

[0108] The storage component can be integrated with the processor, for example, by arranging RAM or flash memory within an integrated circuit microprocessor, etc. In addition, the storage component can include independent devices, such as external disk drives, storage arrays, or other storage devices that can be used by any database system. The storage component and the processor can be operatively coupled or can communicate with each other, for example, through I / O ports, network connections, etc., so that the processor can read files stored in the storage component.

[0109] In addition, the computing device can also include a video display (such as a liquid crystal display) and a user interaction interface (such as a keyboard, a mouse, a touch input device, etc.). All components of the computing device can be connected to each other via a bus and / or a network.

[0110] The physiological optical signal credibility evaluation method according to an exemplary embodiment of the present disclosure can be described as various interconnected or coupled functional blocks or functional diagrams. However, these functional blocks or functional diagrams can be equally integrated into a single logical device or operate with non-exact boundaries.

[0111] Therefore, with reference to Figure 1 The physiological optical signal credibility evaluation method described can be implemented by a system including at least one computing device and at least one storage device storing instructions.

[0112] According to an exemplary embodiment of the present disclosure, at least one computing device is a computing device for performing a physiological optical signal credibility evaluation method according to an exemplary embodiment of the present disclosure. A set of computer-executable instructions is stored in a storage device. When the set of computer-executable instructions is executed by the at least one computing device, it executes with reference to Figure 1 the physiological optical signal credibility evaluation method described.

[0113] According to an exemplary embodiment of the present disclosure, a computer program product may also be provided, including instructions that, when run by at least one computing device, cause the at least one computing device to execute the physiological optical signal credibility evaluation method according to the present disclosure.

[0114] The above describes various exemplary embodiments of the present disclosure. It should be understood that the above description is merely exemplary and not exhaustive, and the present disclosure is not limited to the disclosed exemplary embodiments. Many modifications and variations are obvious to those of ordinary skill in the art in the technical field without departing from the scope and spirit of the present disclosure. Therefore, the protection scope of the present disclosure should be determined by the scope of the claims.

Claims

1. A method for evaluating the credibility of physiological optical signals, characterized in that: include: Acquire multiple physiological optical signal sequences of the same signal channel, wherein each physiological optical signal sequence corresponds to a wavelength and includes multiple physiological optical signals with corresponding wavelengths arranged in a time sequence of acquisition; performing at least one of correlation evaluation and quality evaluation on the plurality of physiological optical signal sequences; Based on the evaluation result of at least one of the correlation evaluation and the quality evaluation, obtaining the credibility information of the signal channel, The correlation evaluation includes: evaluating the correlation between any two of the multiple physiological optical signal sequences, wherein the credibility is positively correlated with the correlation. Wherein, the quality assessment comprises: assessing the signal-to-noise ratio quality of each physiological optical signal sequence in the plurality of physiological optical signal sequences, wherein the credibility is positively correlated with the signal-to-noise ratio quality; Wherein, the step of evaluating the correlation between any two of the plurality of physiological optical signal sequences comprises: Based on the multiple wavelengths corresponding to the multiple physiological optical signal sequences, two different wavelengths are combined into a wavelength pair to obtain multiple wavelength pairs, wherein each wavelength in the multiple wavelengths has a corresponding wavelength pair; For each wavelength pair, a correlation measure of the physiological optical signal sequences at two different wavelengths is calculated; Counting the correlation measures of the multiple wavelength pairs to obtain a correlation index of the signal channel; The correlation is determined according to the correlation indicator.

2. The physiological optical signal credibility assessment method according to claim 1, characterized in that: The step of combining two different wavelengths into a wavelength pair based on the multiple wavelengths corresponding to the multiple physiological optical signal sequences to obtain multiple wavelength pairs includes: Determine a wavelength from a plurality of wavelengths corresponding to the plurality of physiological optical signal sequences as a reference wavelength; The reference wavelength is paired with each wavelength of the plurality of wavelengths except the reference wavelength to obtain the plurality of wavelength pairs.

3. The physiological optical signal credibility assessment method according to claim 1, characterized in that: Determining the correlation according to the correlation indicator includes: When the correlation index is greater than the correlation threshold, the correlation is determined to be relevant; otherwise, the correlation is determined to be irrelevant.

4. The physiological optical signal credibility assessment method according to claim 1, characterized in that: The evaluating the signal-to-noise ratio quality of each physiological optical signal sequence in the plurality of physiological optical signal sequences comprises: Performing filtering processing on each of the multiple physiological optical signal sequences respectively to obtain multiple physiological optical signal sequences within a specified frequency range; Performing power spectral density calculation processing on each of the multiple physiological optical signal sequences within the specified frequency ranges to obtain a power spectral density of each of the multiple physiological optical signal sequences; The signal-to-noise ratio quality is determined according to a power spectral density of each physiological optical signal sequence in the plurality of physiological optical signal sequences.

5. The physiological optical signal credibility assessment method according to claim 4, characterized in that: The determining the signal-to-noise ratio quality according to the power spectral density of each physiological optical signal sequence in the plurality of physiological optical signal sequences comprises: When the peak value of the power spectrum density of each physiological optical signal sequence in the multiple physiological optical signal sequences is greater than the peak threshold, the signal-to-noise ratio quality is determined to be passed; otherwise, the signal-to-noise ratio quality is determined to be failed.

6. A physiological optical signal credibility assessment device, characterized in that: include: an acquisition unit, configured to acquire a plurality of physiological optical signal sequences of the same signal channel, wherein each physiological optical signal sequence corresponds to a wavelength and includes a plurality of physiological optical signals with corresponding wavelengths arranged in a time sequence of acquisition; an evaluation unit configured to perform at least one of a correlation evaluation and a quality evaluation on the plurality of physiological optical signal sequences; a determining unit configured to obtain the credibility information of the signal channel based on an evaluation result of at least one of the correlation evaluation and the quality evaluation, The correlation evaluation includes: evaluating the correlation between any two of the multiple physiological optical signal sequences, wherein the credibility is positively correlated with the correlation. Wherein, the quality assessment comprises: assessing the signal-to-noise ratio quality of each physiological optical signal sequence in the plurality of physiological optical signal sequences, wherein the credibility is positively correlated with the signal-to-noise ratio quality; Wherein, the step of evaluating the correlation between any two of the plurality of physiological optical signal sequences comprises: Based on the multiple wavelengths corresponding to the multiple physiological optical signal sequences, two different wavelengths are combined into a wavelength pair to obtain multiple wavelength pairs, wherein each wavelength in the multiple wavelengths has a corresponding wavelength pair; For each wavelength pair, a correlation measure of the physiological optical signal sequences at two different wavelengths is calculated; Counting the correlation measures of the multiple wavelength pairs to obtain a correlation index of the signal channel; The correlation is determined according to the correlation indicator.

7. A computer-readable storage medium storing instructions, characterized in that: When the instructions are executed by at least one computing device, the at least one computing device is prompted to execute the physiological optical signal credibility assessment method according to any one of claims 1 to 5.

8. A system comprising at least one computing device and at least one storage device storing instructions, characterized in that: When the instructions are executed by the at least one computing device, the at least one computing device is prompted to perform the physiological optical signal credibility assessment method according to any one of claims 1 to 5.

9. A computer program product comprising instructions, characterized in that When the instructions are executed by at least one computing device, the at least one computing device is prompted to perform the physiological optical signal credibility assessment method according to any one of claims 1 to 5.

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