Light source calibration method for improving imaging consistency of image measurement equipment

Abstract

The invention belongs to the technical field of image measurement, and discloses a light source calibration method for improving imaging consistency of image measurement equipment, which comprises a reference light source and a measurement equipment light source, and is characterized by comprising the steps of reference light source selection, measurement equipment light source calibration and measurement equipment light source correction, by collecting the parameters of the reference light source and the light source of the measuring equipment and combining the parameters of the reference light source and the light source of the measuring equipment, the inconsistency of imaging of the image measuring equipment caused by inconsistency of the light sources can be well improved, the consistency of measuring results of different measuring equipment is ensured, and the method is simple to operate and low in cost. K and b can be obtained only through one-time data acquisition and data fitting of reference light sources of the same model; during calibration, data acquired by the illuminometer only needs to be sent into a pre-written least square method to obtain k1 and b1; complex calculation is avoided during correction, and efficiency is high.

Description

Technical Field

[0001] The present invention relates to the field of image measurement technology, and in particular to a light source calibration method for improving imaging consistency of image measurement equipment. Background Art

[0002] When using image measuring equipment for industrial measurement, it is necessary to adjust the brightness of the equipment light source to achieve better imaging effects, thereby making the measurement results more stable. In practical applications, measuring equipment of the same model shares a set of equipment parameters (including camera exposure time, imaging height, and light source brightness) so that batch measurements of the same workpieces can be performed. To ensure the consistency of measurement results of different equipment, it is necessary to ensure the consistency of imaging of different equipment;

[0003] Because different entities of the same type of light source have large differences in actual brightness when the brightness parameters are the same, when different devices of the same type use the same device parameters, the imaging has obvious differences in brightness, which leads to inconsistent measurement results. Summary of the invention

[0004] In view of the shortcomings of the prior art, the present invention provides a light source calibration method for improving the imaging consistency of an image measuring device, which solves the problems raised in the above background technology.

[0005] To solve the above technical problems, according to one aspect of the present invention, more specifically, a light source calibration method for improving the imaging consistency of an image measuring device comprises the following steps:

[0006] S1. Reference light source selection:

[0007] Take a group of target model light sources, use an illuminance meter to collect their "brightness parameter-illuminance value" data, and collect data according to "light source brightness between 2 and 98, with an interval of 2", and obtain a relationship table between brightness parameters and actual brightness, in which the data is fitted by least squares to obtain parameters k and b. The light source uses k and b parameters as references to perform brightness correction on the light source;

[0008] S2. Measurement equipment light source calibration:

[0009] Calibrate the light source of the measuring device according to the method of S1, and use the illuminance meter to collect its "brightness parameter-illuminance value" data, and perform least squares fitting on the data to obtain parameters k1 and b1, and store the reference light source parameters k and b and the measuring device light source parameters k1 and b1 in the configuration file of the measuring device;

[0010] S3. Measurement equipment light source calibration:

[0011] When the measurement device loads the shared device parameters, the k, b, k1 and b1 parameters recorded in the light source calibration process are read to align the actual light source brightness of the measurement device to the brightness of the reference light source, so that different measurement devices can achieve consistent imaging under the same device parameters.

[0012] Furthermore, in S1, the actual brightness of the light source is set to Y, the brightness parameter is set to X, and the least squares fitting is performed on the data according to the linear model Y=k*X+b to obtain parameters k and b.

[0013] Furthermore, in S2, the actual brightness of the light source is set to Y1, the brightness parameter is set to X1, and the least squares fitting is performed on the data according to the linear model Y1=k1*X1+b to obtain parameters k1 and b1.

[0014] Furthermore, in S3, the light source brightness parameter in the shared device parameter is set to x, and x is set as the parameter to the light source of the measuring device, then the actual light source brightness is obtained, represented by y, and the calculation formula is: y=k1*x+b1.

[0015] Furthermore, in S3, due to the inconsistency of the light sources of different devices, that is, the difference between k1 and b1, the actual light source brightness y obtained under the same brightness parameter x is different, resulting in inconsistent brightness of the imaging. Since the reference light source parameters k and b stored when calibrating the light sources of different devices are consistent, if the actual light source brightness y of the measuring device is aligned to the brightness of the reference light source, that is, y=k*x+b, different measuring devices can obtain consistent imaging under the same device parameters.

[0016] Furthermore, in S3, the brightness parameter actually required to be set to the light source is set to x1, and the expected light source brightness is y=k*x+b, and the following formula is obtained:

[0017] k1*x1+b1=k*x+b

[0018] Where k1, b1, k, and b are the parameters obtained during calibration, and x is the light source brightness parameter in the shared device parameters, and the following formula is obtained:

[0019] x1=(k*x+b-b1) / k1

[0020] By setting x1 to the measurement device, you can get the expected light source brightness and keep the imaging consistent.

[0021] The beneficial effects of the light source calibration method for improving the imaging consistency of image measuring equipment of the present invention are as follows:

[0022] The present invention can well improve the inconsistency of imaging of image measuring equipment caused by inconsistent light sources by collecting parameters of a reference light source and a light source of a measuring device, and combine the parameters of the reference light source and the light source of the measuring device, thereby ensuring the consistency of measurement results of different measuring devices. The present invention is simple to operate, and only one data collection and data fitting is required for the same type of reference light source to obtain k and b; during calibration, only the data collected by the illuminometer needs to be sent to a pre-written least square method to obtain k1 and b1; there is no complicated calculation during calibration, and the efficiency is high. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The present invention is further described in detail below with reference to the accompanying drawings and specific implementation methods.

[0024] Figure 1 It is a structural schematic diagram of the reference light source parameter relationship table of the present invention.

[0025] Figure 2 It is a structural schematic diagram of the light source parameter relationship table of the measuring equipment of the present invention.

[0026] Figure 3 It is a structural schematic diagram of the light source parameter relationship table of device A of the present invention.

[0027] Figure 4 It is a structural schematic diagram of imaging comparison before and after light source correction of the present invention. DETAILED DESCRIPTION

[0028] The present invention will be described in detail below with reference to the accompanying drawings and in combination with embodiments. It should be noted that the embodiments and features in the embodiments of the present application can be combined with each other without conflict.

[0029] like Figure 1 As shown, according to one aspect of the present invention, a light source calibration method for improving the imaging consistency of an image measuring device is provided, comprising the following steps:

[0030] S1. Reference light source selection:

[0031] Take a group of target model light sources, use an illuminance meter to collect their "brightness parameter-illuminance value" data, and collect data according to "light source brightness between 2 and 98, with an interval of 2", and obtain a relationship table between brightness parameters and actual brightness, in which the data is fitted by least squares to obtain parameters k and b. The light source uses k and b parameters as references to perform brightness correction on the light source;

[0032] S2. Measurement equipment light source calibration:

[0033] Calibrate the light source of the measuring device according to the method of S1, and use the illuminance meter to collect its "brightness parameter-illuminance value" data, and perform least squares fitting on the data to obtain parameters k1 and b1, and store the reference light source parameters k and b and the measuring device light source parameters k1 and b1 in the configuration file of the measuring device;

[0034] S3. Measurement equipment light source calibration:

[0035] When the measurement device loads the shared device parameters, the k, b, k1 and b1 parameters recorded in the light source calibration process are read to align the actual light source brightness of the measurement device to the brightness of the reference light source, so that different measurement devices can achieve consistent imaging under the same device parameters.

[0036] In this embodiment, in S1, the actual brightness of the light source is set to Y, the brightness parameter is set to X, and the least squares fitting is performed on the data according to the linear model Y=k*X+b to obtain the parameters k and b.

[0037] In this embodiment, in S2, the actual brightness of the light source is set to Y1, the brightness parameter is set to X1, and the least squares fitting is performed on the data according to the linear model Y1=k1*X1+b to obtain parameters k1 and b1.

[0038] In this embodiment, in S3, the light source brightness parameter in the shared device parameters is set to x, and x is set as the parameter to the light source of the measuring device, then the actual light source brightness is obtained, represented by y, and the calculation formula is: y=k1*x+b1.

[0039] In this embodiment, in S3, due to the inconsistency of light sources of different devices, that is, the difference between k1 and b1, the actual light source brightness y obtained under the same brightness parameter x is different, resulting in inconsistent brightness of the imaging. Since the reference light source parameters k and b stored when calibrating the light sources of different devices are consistent, if the actual light source brightness y of the measuring device is aligned to the brightness of the reference light source (expected light source brightness), that is, y=k*x+b, different measuring devices can obtain consistent imaging under the same device parameters.

[0040] In this embodiment, in S3, the brightness parameter actually required to be set to the light source is set to x1, and the expected light source brightness is y=k*x+b, and the following formula is obtained:

[0041] k1*x1+b1=k*x+b

[0042] Where k1, b1, k, and b are the parameters obtained during calibration, and x is the light source brightness parameter in the shared device parameters, and the following formula is obtained:

[0043] x1=(k*x+b-b1) / k1

[0044] By setting x1 to the measurement device, you can get the expected light source brightness and keep the imaging consistent.

[0045] Example

[0046] 1. Collect reference light source data and fit parameters. After least squares fitting, the reference light source parameters k = 1.683, b = -7.596 are obtained;

[0047] 2. Collect the light source data of device A and calibrate it. After least squares fitting, the light source parameters of device A are obtained as k1=2.382 and b1=-17.59;

[0048] 3. Use device A to load the shared device parameters, where the light source brightness parameter x is 59. According to the formula x1=(k*x+b-b1) / k1, x1=45.8820 is calculated. After rounding, x1=46. Set the x1 parameter to the light source of device A.

[0049] Of course, the above description is not a limitation of the present invention, and the present invention is not limited to the above examples. Changes, modifications, additions or substitutions made by ordinary technicians in this technical field within the essential scope of the present invention also fall within the protection scope of the present invention.

Claims

1. A light source calibration method for improving the imaging consistency of an image measuring device, comprising the following steps: S1. Reference light source selection: Take a group of target model light sources, use an illuminance meter to collect their "brightness parameter-illuminance value" data, and collect data according to "light source brightness between 2 and 98, with an interval of 2", and obtain a table of the relationship between brightness parameters and actual brightness. In this case, the data is fitted with the least square method to obtain parameters k and b. The light source uses the k and b parameters as references to perform brightness correction on the light source. S2. Measurement equipment light source calibration: Calibrate the light source of the measuring device according to the method of S1, and use the illuminance meter to collect its "brightness parameter-illuminance value" data, and perform least squares fitting on the data to obtain parameters k1 and b1, and store the reference light source parameters k and b and the measuring device light source parameters k1 and b1 in the configuration file of the measuring device; S3. Measurement equipment light source calibration: When the measurement device loads the shared device parameters, the k, b, k1 and b1 parameters recorded in the light source calibration process are read to align the actual light source brightness of the measurement device to the brightness of the reference light source, so that different measurement devices can achieve consistent imaging under the same device parameters.

2. A light source calibration method for improving imaging consistency of image measuring equipment according to claim 1, characterized in that: In S1, the actual brightness of the light source is set to Y, the brightness parameter is set to X, and the least squares fitting is performed on the data according to the linear model Y=k*X+b to obtain parameters k and b.

3. A light source calibration method for improving imaging consistency of image measuring equipment according to claim 1, characterized in that: In S2, the actual brightness of the light source is set to Y1, the brightness parameter is set to X1, and the least squares fitting is performed on the data according to the linear model Y1=k1*X1+b to obtain parameters k1 and b1.

4. The method for calibrating a light source for improving the imaging consistency of an image measuring device according to claim 1, characterized in that: In S3, the light source brightness parameter in the shared device parameters is set to x, and x is set as the parameter to the light source of the measuring device, then the actual light source brightness is obtained, represented by y, and the calculation formula is: y=k1·x+b1.

5. The method for calibrating a light source for improving the imaging consistency of an image measuring device according to claim 1, characterized in that: In S3, due to the inconsistency of light sources of different devices, that is, the difference between k1 and b1, the actual light source brightness y obtained under the same brightness parameter x is different, resulting in inconsistent brightness of the imaging. Since the reference light source parameters k and b stored when calibrating the light sources of different devices are consistent, if the actual light source brightness y of the measuring device is aligned to the brightness of the reference light source, that is, y=k*x+b, different measuring devices can obtain consistent imaging under the same device parameters.

6. A light source calibration method for improving imaging consistency of image measuring equipment according to claim 5, characterized in that: In S3, the brightness parameter actually required to be set to the light source is set to x1, and the expected light source brightness is y=k*x+b, and the following formula is obtained: k1*x1+b1=k*x+b Where k1, b1, k, and b are the parameters obtained during calibration, and x is the light source brightness parameter in the shared device parameters, and the following formula is obtained: x1=(k*x+b-b1) / k1 By setting x1 to the measurement device, you can get the expected light source brightness and keep the imaging consistent.

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