KR102085625B1 - Thermal image camera having multi-point temperature compensating function and temperature compensating method using the same - Google Patents

Abstract

Disclosed are a thermal imaging apparatus having a multi-point temperature correction function and a temperature correction method using the same.
A thermal imaging camera unit including a plurality of infrared image sensors installed at regular intervals and acquiring a thermal image through each infrared image sensor; After detecting at least one object from each image data input from the thermal camera unit, the distance between the camera and each object is measured, and each object is measured according to the distance measured for each object. A thermal image data processor to correct the temperature; And a thermal image data monitoring unit for transmitting the temperature data corrected by the thermal image data processing unit to an output device.

Description

Thermal imaging device with multi-point temperature correction function and temperature correction method using the same

The present invention relates to a thermal imaging apparatus having a multi-point temperature correction function and a temperature correction method using the same, and more particularly, after measuring a distance to a target object using a plurality of infrared image sensors, The present invention relates to a thermal imaging apparatus having a temperature correction function for correcting a temperature according to a distance measured for each measurement object and displaying the same on a screen, and a temperature correction method using the same.

In general, a thermal imaging camera is a device that detects infrared energy from an object to be photographed to measure temperature and outputs and monitors the measured temperature as an image or video. Unlike this, the device focuses on temperature measurement.

Since the thermal imaging camera is a device focused on temperature measurement, the temperature value measured by the thermal imaging camera is one of the most important factors.

The data input from the thermal imaging camera is digital data, and since the input data is not an absolute temperature value, a work that needs to be corrected for the actual temperature is required.

Various input parameters are used in the correction process, and the input factors may include emissivity, atmospheric transmittance, window transmittance, window reflectance, and the like as shown in FIG. 1.

Table 1 shows the characteristics of representative input factors that affect the calibration process.

Input argument characteristic Emissivity Heat release rate from the surface of the object under test (value from 0.3 to 1 depending on surface material) Atmospheric transmittance Fluctuation factor dust, humidity, distance, and reflection between the object under test and the thermal image sensor, the biggest factor is distance. Distance acts as the gain value of the formula Window transmittance Rate of heat source passing through the lens and protective window in front of the thermal sensor (fixed value)

In order to measure temperature using a thermal imaging camera, the three input parameters of Table 1 must be set in the camera to obtain reliable temperature data. Here, the emissivity can be pre-populated with characteristics according to the surface material of the object under test. The window transmittance can be set by calibration at the time of manufacturing the camera.

However, the air permeability should be set separately for each distance if multiple objects are located at different distances.

That is, even if a plurality of subjects have the same temperature, if the distance between the thermal imaging camera and the subject is different, the measured temperature value is different, and even if the subjects have the same temperature, the subject close to the camera will be The temperature value is displayed high, and the subject far from the camera is displayed at a low temperature value.

The reason for this is that the amount of air through which light (infrared rays) can transmit varies according to the distance between the thermal imaging camera and the object under test, and the amount of radiation and reflection varies depending on the amount of air through which light (infrared rays) transmits. Because it can.

Therefore, in the related art, when a plurality of objects to be measured are located at different distances as shown in FIG. 2, there is a troublesome problem of correcting the temperature by setting an air transmittance separately for each distance.

Korean Registered Patent Publication No. 10-0200672 (Notice date 1999.06.15.) Korean Patent Publication No. 10-2014-0117745 (Publication date 2014.10.08.) Korean Registered Patent Publication No. 101833137 (Notice date 2018.02.28.)

The present invention has been made to solve the above-described problem, by installing a plurality of infrared image sensor in a stereo method to measure the distance between the camera and the object to be measured, and performs individual temperature correction according to the measured distance for each object It is an object of the present invention to provide a thermal imaging apparatus having a multi-point temperature correction function and a temperature correction method using the same.

Another object of the present invention is a column having a multi-point temperature correction function for displaying the object under test with a temperature value corresponding to the corrected temperature when the individual temperature correction is made according to the distance measured for each object to be measured. An image camera device and a temperature correction method using the same are provided.

According to an embodiment of the present invention, a thermal imaging camera apparatus having a multi-point temperature correction function includes a plurality of infrared image sensors installed at regular intervals, and through each infrared image sensor. A thermal camera unit for acquiring a thermal image; After detecting at least one or more to-be-measured object from each of the image data input from the thermal imaging camera unit, measuring the distance between the camera and each object to be measured, and correcting the temperature according to the measured distance for each object A thermal image processing unit; And a thermal image data monitoring unit for transmitting the temperature data corrected by the thermal image data processing unit to an output device.

In one embodiment of the present invention, the thermal image data processing unit receives the image data obtained through the respective infrared image sensor from the thermal imager to detect a temperature value for each pixel, and detected temperature value A measurement object detecting unit which detects at least one measurement object by using; A distance measuring unit configured to select one coordinate as a specific coordinate for each target object detected by the target object detection unit, and measure a distance between the camera and each target object using the selected specific coordinates; And a temperature correction unit extracting a correction coefficient for each target object according to the distance measured for each target object by the distance measuring unit, and correcting a temperature for each target object using the correction coefficient extracted for each target object. It is preferable to make it.

In one embodiment of the present invention, the object detecting unit detects at least one or more objects under measurement using the detected temperature value, when the data of a temperature value different from the background temperature value is input, it is separated from the background The object to be detected is preferably detected by using any one of a background removal technique for detecting the object under measurement and a motion detection technique for detecting the object with the object under continuous motion.

In one embodiment of the present invention, the distance measuring unit, it is preferable to apply the selected specific coordinates to the triangulation technique to measure the distance between the camera and each object to be measured.

In one embodiment of the present invention, the distance measuring unit is a parallel type measuring the distance by using the distance between the infrared image sensor and the position difference of the measured object shown in the image obtained from the plurality of infrared image sensor installed to face the front It is preferable to measure the distance between the camera and each subject by using any one of a technique, a crossover technique of measuring the distance using the angle of a plurality of infrared image sensors whose angle is adjusted so that the subject is centered. Do.

On the other hand, the temperature correction method using a thermal imaging apparatus having a multi-point temperature correction function according to an embodiment of the present invention, the thermal imaging image using a plurality of infrared image sensor which is installed at regular intervals Obtaining; The thermal image data processor detects at least one object from each image data input from the thermal camera, and measures a distance between the camera and each object, and measures the distance measured for each object. Correcting the temperature according to the measurement target object; And outputting the temperature data corrected by the thermal image data processor to the screen by the thermal image data monitoring unit.

In one embodiment of the present invention, the step of correcting the temperature, the image data obtained from each of the infrared image sensor in the target object detection unit of the thermal image data processing unit receives the image data from the thermal imaging camera unit to each pixel Detecting at least one temperature value, and detecting at least one subject under test using the detected temperature value; Selecting one coordinate for each of the detected target objects by the distance measuring unit of the thermal image data processor, and measuring a distance between the camera and each target object using the selected coordinates; And extracting a correction coefficient for each target object according to the distance measured for each target object by the temperature correction unit of the thermal image data processor, and correcting a temperature for each target object using the correction coefficient extracted for each target object. It is preferable that a step comprising.

Thermal imaging apparatus having a multi-point temperature correction function and a temperature correction method using the same according to the present invention, by installing a plurality of thermal imaging camera in a stereo method to measure the distance between the camera and the subject under measurement, measured by each subject By performing the individual temperature corrections according to the distances obtained, reliable temperature data can be obtained.

In addition, the object under test can be displayed on the screen by the temperature value of the individual temperature correction.

1 is a diagram illustrating an input factor used for temperature correction of a thermal imaging apparatus.
FIG. 2 is a diagram for describing atmospheric transmittance according to a distance between a thermal imaging camera and a target object.
3 is a view schematically showing the configuration of a thermal imaging apparatus having a multi-point temperature correction function according to an embodiment of the present invention.
4 is a view for explaining the correlation between the installation interval and the distance measurement range between the thermal imaging camera applied to the present invention.
FIG. 5 is a diagram for describing a background removing technique in the object detecting technique applied to the present invention.
6 is a view for explaining a motion detection technique of the object detection technique applied to the present invention.
7 is a diagram illustrating specific coordinates of an object to be applied to the present invention by way of example.
8 is a view for explaining a triangulation technique of the distance detection technique applied to the present invention.
9 is a view for explaining a parallel technique of the distance detection technique applied to the present invention.
FIG. 10 is a view schematically showing information processed and output by a thermal image data processor according to the present invention.
11 is a flowchart illustrating a temperature correction method using a thermal imaging apparatus having a multi-point temperature correction function according to an embodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION The following detailed description of the invention refers to the accompanying drawings that show, by way of illustration, specific embodiments in which the invention may be practiced. These embodiments are described in sufficient detail to enable those skilled in the art to practice the invention. It is to be understood that the various embodiments of the invention are different but need not be mutually exclusive. For example, certain shapes, structures, and characteristics described herein may be embodied in other embodiments without departing from the spirit and scope of the invention in connection with one embodiment. In addition, it is to be understood that the location or arrangement of individual components within each disclosed embodiment may be changed without departing from the spirit and scope of the invention. Accordingly, the following detailed description is not to be taken in a limiting sense, and the scope of the present invention, if properly described, is defined only by the appended claims, along with the full range of equivalents to which such claims are entitled. Like reference numerals in the drawings refer to the same or similar functions throughout the several aspects.

Hereinafter, a thermal imaging apparatus having a multi-point temperature correction function and a temperature correction method using the same will be described in detail with reference to the accompanying drawings.

3 is a view schematically showing the configuration of a thermal imaging apparatus having a multi-point temperature correction function according to an embodiment of the present invention.

As shown in FIG. 3, the thermal imaging apparatus 100 having a multi-point temperature correction function according to an embodiment of the present invention includes a thermal imaging camera unit 110, a data transmission / reception unit 120, and thermal image data. It may include a processing unit 130, thermal image data monitoring unit 140.

The thermal imager 110 measures an infrared energy emitted by a subject and outputs an image of the surface temperature to a specific range of values (for example, a value between 0 and 255), and outputs the plurality of infrared images. It may comprise a sensor (preferably two infrared image sensors) 111, a thermal image sensor 113, the A / D converter 115.

Each infrared image sensor 111 passes through infrared rays emitted from the object under test to obtain a thermal image.

The plurality of infrared image sensors 111 may be installed at a predetermined distance between left and right.

As described above, when the infrared image sensor 111 is installed at a certain distance, the infrared image sensor 111 is input from an image (or image) input when the two infrared image sensors 111 look at the same object under test. Due to the distance therebetween, the position of the object to be measured is different from each other, and the distance between the infrared image sensor 111 and the object to be measured is measured using a difference value of the position generated as described above.

That is, the closer the distance between the infrared image sensor 111 and the object under measurement is, the larger the position difference value of the subjects input to the two infrared image sensors 111 becomes, and the infrared image sensor 111 and the object under measurement are larger. As the distance between them increases, the position difference value of the subjects input to the two infrared image sensors 111 becomes smaller, and the distance between the infrared image sensor 111 and the subject is measured.

The range in which the distance can be measured may vary according to the installation intervals of the plurality of infrared image sensors 111.

As shown in FIG. 4, it can be seen that the installation interval b is smaller in the distance measurement range than the installation interval a between the infrared image sensors 111 having the same viewing angle (installation interval a <installation interval b).

Therefore, the spacing between the infrared image sensors 111 is very important.

In addition, the range in which the distance can be measured may vary depending on the viewing angle of the lens, and the narrower the viewing angle of the lens, the narrower the range of measurement, and the wider the viewing angle of the lens, the wider the range of measurement.

As described above, since the installation interval between the infrared image sensors 111 may act as a variable, it is preferable not to change the interval between the infrared image sensors 111 once set, and if necessary, the calculated value according to the change. Since this is different, the coefficient value for the distance calculation must also be changed.

The thermal image sensor 113 detects infrared rays from the thermal image images acquired by the plurality of infrared image sensors 111 and converts the infrared rays into electrical signals.

In one embodiment of the present invention, the thermal image sensor 113 may have a focal plane array (FPA) structure in which a plurality of pixels (pixels) are configured in a two-dimensional array, but is not limited thereto.

When the thermal image sensor 113 has the FPA structure as described above, the thermal image sensor 113 detects the magnitude of the infrared energy for each pixel determined according to the resolution of the FPA, and outputs a value corresponding thereto.

The A / D converter 115 converts the output value of the electrical signal output from the thermal image sensor 113 into a digital signal, and transfers the output value converted into the digital signal to the data transceiver 120.

Here, the thermal image sensor 113 and the A / D converter 115 may be implemented by being mounted separately in a separate equipment housing for each infrared image sensor 111, or each infrared image sensor (in one equipment housing) Both the thermal image sensor 113 and the A / D converter 115 for the 111 may be mounted and implemented.

The data transmission / reception unit 120 receives data from the thermal imaging camera unit 110 and stores the data in a buffer or transmits various commands received from the microprocessor unit (MPU) to the thermal imaging camera unit 110. Here, serial communication is mainly used for data transmission and reception, but parallel communication may be used in some cases.

Since the data received from the thermal camera unit 110 is mainly image (or image) data, the data is configured in a fairly large packet or payload unit.

Therefore, it is desirable to select a communication device or MPU having an appropriate buffer size and processing speed.

The thermal image processing unit 130 detects at least one or more measurement targets from the image data received from the thermal imaging camera unit 110, and then measures and measures the distance between the thermal imaging device 100 and the measurement target. Calibrate the temperature for each subject under the distance specified.

The thermal image processor 130 may include a target object detector 131, a distance measurer 133, and a temperature corrector 135.

The object detecting unit 131 receives image data acquired through each infrared image sensor 111 from the thermal imaging camera unit 110, detects a temperature value for each pixel, and uses the detected temperature value. Detect at least one subject. Here, the temperature value used to detect the object to be measured may be a raw result temperature data or a temperature result value corrected by a temperature correction formula.

The target object detecting unit 131 detects the target object by using the detected temperature value, but detects the target object by using a background removal technique or a motion detection technique.

As illustrated in FIG. 5, the background removing technique processes data accumulated in a predetermined threshold range as a background, and when data having a temperature value different from that of the background is input, is separated from the background and detected as a subject under measurement.

The motion detection technique detects an object under measurement when an object in the form of a continuously moving block occurs as shown in FIG. 6.

When at least one object is detected by the object detecting unit 131, the distance measuring unit 133 selects one coordinate as a specific coordinate for each detected object and uses the selected specific coordinates. Measure the distance between the camera and each subject.

Herein, as a method of selecting specific coordinates, as shown in FIG. 7, after blocking a target object, coordinates of a specific position such as the coordinates of one of the corners or the center coordinates of the block may be selected as the specific coordinates. Can be.

In addition, the maximum temperature point of the detected target object (if the temperature correction is well done, since the position of the maximum temperature point will be almost the same) can be selected as a specific coordinate.

Here, instead of the specific coordinates, a specific block of small pixel units (eg, 2 × 2) including the specific coordinates may be used.

When a specific coordinate (or a specific block) is selected, the distance measuring unit 133 applies the triangulation technique as shown in FIG. 8 using the selected specific coordinate (or specific block) to apply the thermal imaging apparatus 100. And the distance between each target object (target). That is, the angle between each infrared image sensor 111 and the measured object calculated using the distance interval between the two infrared image sensors 111 and the position of the measured object in the image acquired by the two infrared image sensors 111 is determined. The distance between the thermal imaging camera device 100 and the object under test is measured.

The distance measuring unit 133 may measure the distance between the thermal imaging apparatus 100 and the object to be measured using a parallel technique or a cross technique according to a camera installation method.

In the parallel technique, as shown in FIG. 9, the plurality of infrared image sensors 111 are installed to face side by side, and the distance and the position between the infrared image sensors 111 are fixed so that the images of the two infrared image sensors 111 are fixed. The distance between the thermal imaging apparatus 100 and the object to be measured is measured through a series of calculations using the position difference between the object to be measured (target) and the distance between the two infrared image sensors 111. As described above, when the distance between the thermal imaging apparatus 100 and the object to be measured is measured through a parallel technique, the installation angle of the infrared image sensor 111 may be installed at an angle depending on the situation. The reference angle of the installation of the infrared image sensor 111 is preferably installed so that the infrared image sensor 111 faces the front side by side when the monitoring target of the target object is narrow, and the infrared image sensor 111 is wide when the monitoring range is wide. It is preferable to install the angle obliquely inward.

Unlike the parallel technique, the cross technique uses a physically adjusted angle of the infrared image sensor 111 to physically adjust the angle of the infrared image sensor 111 so that the subject always appears in the center of the image. The distance between the image camera device 100 and the object under test is measured.

The temperature corrector 135 corrects the temperature by applying an input factor to a temperature correction formula using emissivity, atmospheric transmittance, window transmittance, and the like, and extracts a correction coefficient for each object to be measured according to the distance measured by the distance measurer 133. The temperature is corrected for each subject using the correction coefficient extracted for each subject.

The above-described thermal image data processing unit 130 detects a temperature for each pixel in the image data received from the thermal image camera unit 110 through the data transmission and reception unit 120 as shown in FIG. Measures the distance between the camera and the object to be used, and extracts various information (e.g., image (or image) data, coordinates having a maximum temperature value, coordinates having a minimum temperature value, etc.) for output to an output device Perform arithmetic processing to

The thermal image processing unit 130 preferably supports a high processing speed for processing a large storage space and image data, and performing a real-time calculation for measuring a distance between a camera and a target object.

The thermal image data monitoring unit 140 transmits the temperature data corrected by the thermal image data processing unit 130 and the image (or image) data processed by the thermal image data processing unit 130 to the output device.

Here, when the output device is a monitor screen, the detected target object is displayed on one screen, and the thermal target data processor 130 displays the target object with the temperature value corrected for each target object. Accordingly, when a plurality of subjects have the same temperature to each other, even if each subject is located at a different distance from the camera, the same temperature value (color) is displayed on the screen.

The format of the data packet (or payload) may vary according to the interface of the output device, or the provided user interface (UI) may be used.

11 is a flowchart illustrating a temperature correction method using a thermal imaging apparatus having a multi-point temperature correction function according to an embodiment of the present invention, and a column having a multi-point temperature correction function according to an embodiment of the present invention. Since the temperature correction method using the image camera device proceeds on substantially the same configuration as the thermal image camera device 100 having the multi-point temperature correction function shown in FIG. 3, the same configuration as the thermal image camera device 100 of FIG. The same reference numerals are given to the elements, and repeated descriptions will be omitted.

First, the thermal camera unit 110 acquires a thermal image through a plurality of infrared image sensors (preferably two infrared image sensors) 111 installed at regular intervals (S10).

The thermal image obtained in step S10 may be implemented as two-dimensional image data.

The thermal image obtained through the step S10 is applied to the thermal image data processor 130 through the data transceiver 120.

As described above, the object detecting unit 131 of the thermal image data processing unit 130 that receives the thermal image through the data transmitting and receiving unit 120 detects a temperature value for each pixel (S20).

The target object is detected using the detected temperature value (S30).

In step S30, the object to be detected 131 processes the data accumulated in a predetermined threshold range as a background, and when data having a temperature value different from the background temperature is input, the detected object is separated from the background to be detected as the object to be measured. When an object in the form of a background removal technique or a continuously moving block is generated, the target object may be detected using any one of a motion detection technique for detecting the object as the target object.

When at least one target object is detected through step S30, the distance measuring unit 133 of the thermal image processing unit 130 specifies one coordinate for each target object detected through step S30. The distance between the camera and each subject is measured using the selected specific coordinates (S40).

In step S40, the distance measuring unit 133 blocks the detected object, and then selects or detects a coordinate of a specific position such as a coordinate of one of the corners or the center coordinates of the block. The maximum temperature point of the measured object can be selected in specific coordinates.

In addition, the distance measuring unit 133 may use a specific block of a small pixel unit (for example, 2 × 2) including the specific coordinates instead of the specific coordinates.

As such, when a specific coordinate (or a specific block) is selected, the distance measuring unit 133 measures a distance between the camera 111 and the target object by applying a triangulation technique using the selected specific coordinate (or specific block). Alternatively, the distance between the camera 111 and the object to be measured is measured by using a parallel technique or a cross technique according to a camera installation method.

When the distance between the camera 111 and each of the target objects is measured through the above step S40, the temperature correcting unit 135 of the thermal image data processing unit 130 is measured according to the distance measured in the above step S40. The correction coefficients are extracted for each target, and the temperature is corrected for each target object using the extracted correction coefficients (S50).

When the temperature is corrected for each target object through the above step S50, the thermal image data monitoring unit 140 outputs the corrected temperature data and the image (or image) data to the output device (S60).

In the above step S60, when the output device is a monitor screen, the target object is displayed on the monitor screen with the temperature value corrected for each subject. Accordingly, when a plurality of subjects have the same temperature, even if each subject is located at a different distance from the camera, the temperature is corrected for each subject so that the plurality of subjects have the same temperature value (color on the monitor screen). Is indicated by).

Although described above with reference to the embodiments, those skilled in the art will understand that the present invention can be variously modified and changed without departing from the spirit and scope of the invention described in the claims below. Could be.

100. a thermal imaging camera device, 110. a thermal imaging camera unit,
111. infrared image sensor, 113. thermal image sensor,
115. A / D converter, 120. Data transceiver
130. a thermal image processing unit, 131. a subject-detector detection unit,
133. Distance measurement unit, 135. Temperature correction unit,
140. Thermal image monitoring unit

Claims (7)

A thermal imaging camera unit including a plurality of infrared image sensors installed at regular intervals and acquiring a thermal image through each infrared image sensor;
After detecting at least one or more to-be-measured object from each of the image data input from the thermal imaging camera unit, measuring the distance between the camera and each object to be measured, and correcting the temperature according to the measured distance for each object A thermal image processing unit; And
And a thermal image data monitoring unit for transmitting the temperature data corrected by the thermal image data processing unit to an output device.
The thermal image processing unit,
A target object that receives image data obtained through each infrared image sensor from the thermal camera unit, detects a temperature value for each pixel, and detects at least one or more subjects using the detected temperature value Detection unit;
A distance measuring unit configured to select one coordinate as a specific coordinate for each target object detected by the target object detection unit, and measure a distance between the camera and each target object using the selected specific coordinates; And
A temperature correction unit extracting a correction coefficient for each target object according to the distance measured by the target object in the distance measuring unit, and correcting a temperature for each target object using the correction coefficient extracted for each target object; Done,
The distance measuring unit,
After blocking the object to be detected for each of the detected objects, the coordinates of any one of the center coordinates or four corners of the block are selected as specific coordinates, and the camera and each object are selected using the selected specific coordinates. Measure the distance between the measuring objects,
The output device,
And a multi-point temperature correction function for displaying the object under temperature corrected for each object in the thermal image data processing unit. delete The method of claim 1,
The measurement object detecting unit,
Detecting at least one or more to-be-measured object using the detected temperature value, if the data of the temperature value different from the background temperature is input, the background removal technique for detecting it as a subject by separating it from the background, The thermographic camera apparatus having the multi-point temperature correction function which detects the target object by using any one of a motion detection technique which detects the object with the target object when it occurs. The method of claim 1,
The distance measuring unit,
And applying the selected specific coordinates to a triangulation technique to measure the distance between the camera and each object under test. The method of claim 1,
The distance measuring unit,
A parallel technique of measuring the distance by using the distance between the infrared light sensor and the position of the object in the image acquired by the plurality of infrared image sensors installed facing the front, and adjusting the angle so that the object appears in the center. A thermal imaging camera device having a multi-point temperature correction function for measuring a distance between a camera and each object under test using any one of a crossover technique of measuring a distance using angles of a plurality of infrared image sensors. Acquiring a thermal image by using a plurality of infrared image sensors installed at regular intervals of the thermal camera;
The object detecting unit of the thermal image processing unit receives image data obtained from each infrared image sensor from the thermal camera unit, detects a temperature value for each pixel, and uses at least one detected temperature value to detect the temperature value. Detecting the subject under test;
Selecting one coordinate for each of the detected target objects by the distance measuring unit of the thermal image data processor, and measuring a distance between the camera and each target object using the selected coordinates;
Extracting, by the temperature correction unit of the thermal image data processor, a correction coefficient for each object according to the distance measured for each object, and correcting a temperature for each object by using the correction coefficient extracted for each object. ; And
A thermal image data monitoring unit, transmitting the temperature data corrected for each object to be measured by the thermal image data processor to an output device, and displaying, by the output device, the temperature object corrected for each object to be measured; Including,
In the distance measuring unit of the thermal image processing unit, selecting one coordinate for each detected object and measuring the distance between the camera and each object using the selected coordinates,
After blocking the target object for each of the detected objects in the distance measuring unit of the thermal image data processing unit, a coordinate of any one of the center coordinates or four corners of the block is selected as a specific coordinate, A temperature correction method using a thermal imaging apparatus having a multi-point temperature correction function, which is a step of measuring a distance between a camera and each object under test using specific coordinates. delete

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