CN110749280B - Method, system and computer readable medium for extracting index coordinates of peak position - Google Patents

Abstract

The invention discloses a method, a system and a computer readable medium for extracting a peak position index coordinate, which utilize an optical measurement system to obtain a normalized discrete unimodal signal, utilize a preset intensity threshold value T to obtain the intercepted discrete unimodal signal, calculate a dynamic threshold value of the intercepted discrete unimodal signal and filter the normalized discrete unimodal signal to obtain a new normalized intercepted unimodal signal, thereby realizing the rapid and accurate positioning of the peak position index coordinate of the normalized discrete unimodal signal and improving the measurement accuracy of the optical measurement system.

Description

A method, system and computer-readable medium for extracting peak position index coordinates

technical field

The invention belongs to the field of optical measurement, and in particular relates to a method, a system and a computer-readable medium for extracting peak position index coordinates.

Background technique

It is known that in many optical precision measurement techniques such as confocal microscopy, dispersive confocal microscopy, laser triangulation sensors, star detection, Shack-Hartmann wavefront sensors, and biomacromolecule localization and other optical applications, detection. A one-dimensional or two-dimensional single-peak signal is collected on a detector such as a linear array detector or an area-array detector. In the above measurement technology, the measurement accuracy is directly related to the positioning accuracy of the peak position index coordinates of the single-peak signal.

For example, in confocal microscopy measurement technology, the point light source is focused on the surface of the object to be measured into a light spot through the confocal objective lens and then returns along the original path, and then the light from the object signal is introduced into the pinhole detector through the spectroscope; when the object is located in the objective lens When the focal plane is at the focal plane, the light energy received by the detector is the largest; when the object deviates from the focal plane of the objective lens, the reflected light is focused on a certain position before or behind the pinhole, and the detector only receives a small amount of light energy at this time; In this way, the position of the object relative to the focal plane can be reflected by detecting the intensity change of the light intensity signal by the detector. When the object scans along the optical axis of the objective lens, different light intensities can be obtained at different scanning heights. The optical axis scanning position is used as the index coordinate, and the corresponding pinhole detector intensity is the intensity information. The above two are composed of a single peak signal. During the measurement, the height of the measured position can be obtained by locating the index coordinates of the peak position of the single-peak signal. For another example, in the Shack-Hartmann wavefront sensor, when a light beam is incident on the Hartmann-Shack wavefront sensor, a microlens array on the sensor divides the light beam into many tiny sub-apertures. After each part of the light wave passes through the microlens, it converges on the sub-aperture focal point to form a sub-aperture light spot array image. When the incident light wave is an ideal plane wave, a set of uniformly distributed and regular light spot patterns will be obtained at the focal point of the microlens array, that is, a two-dimensional single-peak signal; when the incident light wave has wavefront distortion, the focal plane of the microlens array will be The array image obtained at , will no longer be uniformly distributed, but deviate from the spot pattern of the ideal wavefront described above. This deviation is measured according to the peak position index coordinates of the two-dimensional single-peak signal, so the wavefront detection accuracy is directly subject to the positioning accuracy of the peak position index coordinates. For a two-dimensional single-peak signal, such as the above-mentioned speckle diagram, the index coordinates have two dimensions, which can respectively represent the pixel index values in two directions in a picture. The coordinates (two coordinates) are actually the positioning of the index coordinates of the peak positions of the two one-dimensional single-peak signals.

The fast, accurate and reliable extraction of the peak position index coordinates of the one-dimensional single-peak signal directly affects the accuracy and reliability of the final measurement result and the measurement frequency, which requires the peak position index coordinate algorithm to have superior peak performance (high accuracy, high reliability ) and good computational efficiency. Existing peak position index coordinate algorithms include large value method (MPM), center of gravity method (COM), parabolic fitting method (PFM), Gaussian fitting method (GFM) and sinc2 fitting method (SFM). Among them, the maximum value method (MPM) directly selects the spectral wavelength corresponding to the maximum light intensity point as the peak value, which is easily affected by noise, but has extremely high computational efficiency; the center of gravity method (COM) has high peak extraction accuracy. The peak extraction accuracy and reliability of the fitting methods such as parabolic fitting method (PFM), Gaussian fitting method (GFM) and sinc2 fitting method (SFM) are higher, but the computational efficiency is higher. Too low, it is difficult to achieve fast online measurement. Take "Influence of sample surface height for evaluation of peak extraction algorithms in confocal microscopy" published in "Applied optics" (Chen C, Wang J, Liu X, et al. Influence of sample surface height for evaluation of peak extractionalgorithms in confocal microscopy [ J].Applied optics, 2018,57(22):6516-6526.) is an example, in the field of confocal microscopy, the accurate and reliable acquisition of the peak value of the axial confocal response signal is to achieve high-precision confocal microscopy. premise. However, since the mathematical model of the actual axial response signal is complex, it is not the Gaussian form or sinc2 form described in the literature, and the fitting peak positioning accuracy based on the mathematical model depends on the difference between the signal model and the mathematical fitting model.

SUMMARY OF THE INVENTION

In view of the above defects or improvement requirements of the prior art, the present invention provides a method, system and computer-readable medium for extracting peak position index coordinates, which use an optical measurement system to obtain a normalized discrete single-peak signal, and use a preset The intensity threshold T obtains the truncated discrete single-peak signal, calculates the dynamic threshold of the truncated discrete single-peak signal, and filters the normalized discrete single-peak signal to obtain a new normalized truncated single-peak signal, thereby realizing Fast and accurate positioning of the index coordinates of the peak position of the normalized discrete single-peak signal to improve the measurement accuracy of the optical measurement system.

In order to achieve the above object, according to one aspect of the present invention, a method for extracting the index coordinates of the peak position is provided, and the specific steps include:

S1. Use the optical measurement system to obtain the index coordinates and intensity information of the discrete single-peak signal, and obtain a normalized discrete single-peak signal, where x _k and I _k are the kth sampling point of the normalized discrete single-peak signal, respectively The index coordinates and light intensity value of , k=1,...,i, i is the number of sampling points of the normalized discrete signal;

S2. Preset the intensity threshold T, and intercept the sampling point information of the normalized discrete single-peak signal intensity greater than or equal to the threshold T to obtain the intercepted discrete single-peak signal, wherein x _j ^c and I _j ^c are the intercepted discrete single-peak signals respectively. The index coordinate and light intensity value at the jth sampling point in the single-peak signal, j=1,...,n, where n is the number of sampling points of the discrete single-peak signal after interception;

S3. Calculate the dynamic threshold T _d of the truncated discrete single-peak signal. The specific calculation process of the dynamic threshold T _d is as follows:

Wherein, c ₁ is the first weight parameter, c ₂ is the second weight parameter, and p ₀ is the reference peak position index coordinate;

S4. Filter out the discrete points where the light intensity I _k is less than the dynamic threshold T _d in the normalized discrete single-peak signal, and obtain a new normalized intercepted single-peak signal, where x _l and I _l are the new normalized The index coordinate and light intensity value at the l-th sampling point of the intercepted single-peak signal are normalized, l=1,...,m, where m is the number of sampling points of the new normalized discrete single-peak signal;

从而实现对归一化离散的单峰信号的峰值位置索引坐标的快速准确定位，以提高光学测量系统的测量准确度。S5. Use the index coordinates and light intensity value of the new normalized discrete single-peak signal and the dynamic threshold T _d to obtain the index coordinates of the peak position of the normalized discrete single-peak signal

Thereby, the fast and accurate positioning of the index coordinates of the peak position of the normalized discrete single-peak signal is realized, so as to improve the measurement accuracy of the optical measurement system.

As a further improvement of the present invention, the optical measurement system is any one of confocal microscope, dispersive confocal microscope, laser triangulation sensor, starry sky detection and Hartmann-Shack wavefront sensor.

As a further improvement of the present invention, the index coordinates of the reference peak position are obtained by the barycentric method or the fitting method.

As a further improvement of the present invention, the reference peak position index coordinates are specifically:

第二权重参数为：

As a further improvement of the present invention, the first weight parameter is:

The second weight parameter is:

Among them, X is the ideal peak position index coordinate of the normalized discrete single peak signal.

In order to achieve the above object, according to another aspect of the present invention, there is provided a system for extracting peak position index coordinates, comprising at least one processing unit and at least one storage unit, wherein the storage unit stores a computer program, and when the program is processed When the unit is executed, the processing unit is caused to execute the steps of the above method.

In order to achieve the above object, according to another aspect of the present invention, a computer readable medium is provided, which stores a computer program executable by a terminal device, and when the program runs on the terminal device, the terminal device performs the steps of the above method. .

In general, compared with the prior art, the above technical solutions conceived by the present invention have the following beneficial effects:

1. A method, system and computer-readable medium for extracting peak position index coordinates of the present invention, which utilizes an optical measurement system to obtain a normalized discrete single-peak signal, and utilizes a preset intensity threshold T to obtain an intercepted discrete single-peak signal. signal, calculate the dynamic threshold of the truncated discrete single-peak signal and filter the normalized discrete single-peak signal to obtain a new normalized truncated single-peak signal, thereby realizing the normalized discrete single-peak signal. Fast and accurate positioning of the index coordinates of the peak position to improve the measurement accuracy of the optical measurement system. At the same time, since the dynamic threshold is not only related to the intensity points before and after the global threshold, but also related to other points, and also involves the derivative information of the discrete signal , that is, the calculation of the dynamic threshold makes more full use of the original discrete signal, so even when the sampling interval is large, that is, when the actual discrete sampling points are few, it still has a very superior peak positioning performance, which is suitable for those with special computational efficiency. Sensitive application areas. It can greatly reduce the systematic error and standard deviation of peak extraction, and does not depend on the model of the axial response signal, which can greatly improve the accuracy and reliability of peak extraction.

2. A method, system and computer-readable medium for extracting peak position index coordinates of the present invention, the proposed dynamic threshold centroid method has the advantages of simple algorithm and high computational efficiency, although it is developed around the processing of one-dimensional signals in a confocal microscope. , but according to the fields of confocal microscopy, dispersive confocal microscopy, laser triangulation sensors, star detection, Hartmann-Shack wavefront sensors, biomacromolecule localization and other fields, one-dimensional and two-dimensional signals have the same signal characteristics and peak localization requirements, so also It can be applied to the fast, high-accuracy and high-reliability extraction of the peaks of Gaussian-like signals in the above-mentioned applications.

Detailed ways

In order to make the objectives, technical solutions and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention, but not to limit the present invention.

In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other. The present invention will be further described in detail below in conjunction with specific embodiments.

For the sake of clarity, it is convenient to introduce definitions of many terms used throughout this disclosure. Generally, these terms are used consistently within the meanings defined herein. However, in some instances, these terms may be assigned different meanings and/or further interpretations depending on their context.

Single peak signal: refers to the intensity data and corresponding index coordinates received by a detector such as a linear array detector or an area array detector, and there is only one strongest position within the index coordinate range;

Index coordinate: refers to the position corresponding to the sampling intensity data in the discrete single-peak signal; for a one-dimensional discrete single-peak signal, the index coordinate refers to the one-dimensional position of the sampling point; and for a two-dimensional discrete single-peak signal, the index coordinate refers to the sampling point the two-dimensional position of the point;

Intensity data: refers to the intensity value of the single peak signal under the specified index coordinate;

Peak position index coordinate: refers to the index coordinate determined by applying a certain rule based on the discrete single-peak signal. The value of the index coordinate is similar to the index coordinate corresponding to the peak point of the intensity data in the discrete single-peak signal.

Reference peak position index coordinate: refers to the peak position index coordinate determined based on the discrete single-peak signal.

Ideal peak position index coordinate: refers to the position corresponding to the maximum point of intensity data in the continuous single-peak signal.

A method for extracting the index coordinates of the peak position of a single peak signal, the specific steps include:

S1. Use the optical measurement system to obtain the index coordinates and intensity information of the discrete single-peak signal, and obtain a normalized discrete single-peak signal, where x _k and I _k are the kth sampling point of the normalized discrete single-peak signal, respectively The index coordinates and light intensity value of , k=1,...,i, i is the number of sampling points of the normalized discrete signal;

As a preferred solution, the optical measurement system can be any one of a confocal microscope, a dispersive confocal microscope, a laser triangulation sensor, a starry sky detection, and a Hartmann-Shack wavefront sensor.

S2. Preset the intensity threshold T, and intercept the sampling point information of the normalized discrete single-peak signal intensity greater than or equal to the threshold T to obtain the intercepted discrete single-peak signal, wherein x _j ^c and I _j ^c are the intercepted discrete single-peak signals respectively. The index coordinate and light intensity value at the jth sampling point in the single-peak signal, j=1,...,n, where n is the number of sampling points of the discrete single-peak signal after interception;

As an example, the intensity threshold T may be set based on empirical values.

S3. Calculate the dynamic threshold T _d of the truncated discrete single-peak signal. The specific calculation process of the dynamic threshold T _d is as follows:

Wherein, c ₁ is the first weight parameter, c ₂ is the second weight parameter, and p ₀ is the reference peak position index coordinate;

The reference peak position index coordinate p ₀ can be obtained by using the existing method for obtaining the reference peak position index coordinate in the prior art, and as a preferred solution, it can be obtained by the center of gravity method or the fitting method;

As a more preferred solution, the reference peak position index coordinates are specifically:

Further, the relationship between the positioning error of the existing peak positioning calculation formula and the ideal peak value can be used:

X为归一化的离散单峰信号的理想峰值位置索引坐标，e为定位误差，p为归一化的离散单峰信号的峰值位置索引坐标；in,

X is the ideal peak position index coordinate of the normalized discrete single-peak signal, e is the positioning error, and p is the peak position index coordinate of the normalized discrete single-peak signal;

和

Furthermore, the relationship between the positioning error of the existing peak positioning calculation formula and the ideal peak value is used to obtain the first weight parameter and the second weight parameter, which are respectively:

and

S4. Filter out the discrete points where the light intensity I _k is less than the dynamic threshold T _d in the normalized discrete single-peak signal, and obtain a new normalized intercepted single-peak signal, where x _l and I _l are the new normalized The index coordinate and light intensity value at the l-th sampling point of the intercepted single-peak signal are normalized, l=1,...,m, where m is the number of sampling points of the new normalized discrete single-peak signal;

从而实现对归一化离散的单峰信号的峰值位置索引坐标的快速准确定位，以提高光学测量系统的测量准确度。S5. Use the new normalized discrete single-peak signal and the dynamic threshold T _d to obtain the peak position index coordinates of the normalized discrete single-peak signal

Thereby, the fast and accurate positioning of the index coordinates of the peak position of the normalized discrete single-peak signal is realized, so as to improve the measurement accuracy of the optical measurement system.

A system for extracting peak position index coordinates includes at least one processing unit and at least one storage unit, wherein the storage unit stores a computer program, which when executed by the processing unit causes the processing unit to execute the steps of the above method.

A computer-readable medium storing a computer program executable by a terminal device, when the program runs on the terminal device, causes the terminal device to execute the steps of the above method.

Take two peak index coordinate algorithms in the prior art as an example, wherein, the two algorithms are global threshold centroid method (STCM) and sinc2 fitting method (SFM), respectively, calculate the systematic error, standard deviation and Computational efficiency, it can be seen from the comparison that the calculation efficiency and accuracy of the extraction method of the embodiment of the present invention are much higher than the above two algorithms. Therefore, the extraction method of the embodiment of the present invention has the peak extraction performance of fast, high accuracy and high reliability.

Those skilled in the art can easily understand that the above are only preferred embodiments of the present invention, and are not intended to limit the present invention. Any modifications, equivalent replacements and improvements made within the spirit and principles of the present invention, etc., All should be included within the protection scope of the present invention.

Claims (6)

1. a method for extracting peak position index coordinates, is characterized in that, concrete steps comprise: S1. Use the optical measurement system to obtain the index coordinates and intensity information of the discrete single-peak signal, and obtain a normalized discrete single-peak signal, where x _k and I _k are the kth sampling point of the normalized discrete single-peak signal, respectively The index coordinates and light intensity value of , k=1,...,i, i is the number of sampling points of the normalized discrete signal; S2. Preset the intensity threshold T, intercept the information of the sampling points whose intensity of the normalized discrete single-peak signal is greater than the threshold T to obtain the intercepted discrete single-peak signal, wherein x _j ^c and I _j ^c are respectively the discrete single-peak signal after interception The index coordinate and light intensity value at the jth sampling point in the peak signal, j=1,...,n, where n is the number of sampling points of the truncated discrete single-peak signal; S3. Calculate the dynamic threshold T _d of the truncated discrete single-peak signal. The specific calculation process of the dynamic threshold T _d is as follows:

Wherein, c ₁ is the first weight parameter, c ₂ is the second weight parameter, and p ₀ is the reference peak position index coordinate; The first weight parameter is:

The second weight parameter is:

Among them, X is the ideal peak position index coordinate of the normalized discrete single-peak signal; S4. Filter out the discrete points where the light intensity I _k is less than the dynamic threshold T _d in the normalized discrete single-peak signal, and obtain a new normalized intercepted single-peak signal, where x _l and I _l are the new normalized The index coordinate and light intensity value at the l-th sampling point of the intercepted single-peak signal are normalized, l=1,...,m, where m is the number of sampling points of the new normalized discrete single-peak signal; S5. Use the new normalized discrete single-peak signal and the dynamic threshold T _d to obtain the peak position index coordinates of the normalized discrete single-peak signal

Thereby, the fast and accurate positioning of the index coordinates of the peak position of the normalized discrete single-peak signal is realized, so as to improve the measurement accuracy of the optical measurement system. 2. a kind of method for extracting peak position index coordinates according to claim 1, is characterized in that, described optical measurement system is confocal microscope, dispersive confocal microscope, laser triangulation sensor, starry sky detection and Hartmann Shack wavefront any of the sensors. 3 . The method for extracting peak position index coordinates according to claim 1 , wherein the reference peak position index coordinates are obtained by using a barycentric method or a fitting method. 4 . 4. The method for extracting peak position index coordinates according to claim 1 or 2, wherein the reference peak position index coordinates are specifically:

5. A system for extracting peak position index coordinates, comprising at least one processing unit and at least one storage unit, wherein the storage unit stores a computer program, and when the program is executed by the processing unit , so that the processing unit executes the steps of the method according to any one of claims 1 to 4 . 6. A computer-readable storage medium, characterized in that it stores a computer program executable by a terminal device, and when the program runs on the terminal device, the terminal device is made to execute any one of claims 1 to 4. The steps of the method are required.