CN113252178A - Point-by-point pixel error calibration method for infrared module - Google Patents
Point-by-point pixel error calibration method for infrared module Download PDFInfo
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- CN113252178A CN113252178A CN202110508582.4A CN202110508582A CN113252178A CN 113252178 A CN113252178 A CN 113252178A CN 202110508582 A CN202110508582 A CN 202110508582A CN 113252178 A CN113252178 A CN 113252178A
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- 238000000034 method Methods 0.000 title claims abstract description 12
- 239000011159 matrix material Substances 0.000 claims description 11
- 238000012937 correction Methods 0.000 claims description 7
- 238000009529 body temperature measurement Methods 0.000 abstract description 14
- 238000003331 infrared imaging Methods 0.000 abstract description 9
- 238000003384 imaging method Methods 0.000 description 4
- 230000005855 radiation Effects 0.000 description 4
- 238000010586 diagram Methods 0.000 description 3
- 230000007613 environmental effect Effects 0.000 description 3
- 238000004519 manufacturing process Methods 0.000 description 2
- 230000002265 prevention Effects 0.000 description 2
- 238000012795 verification Methods 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 1
- 239000008358 core component Substances 0.000 description 1
- 230000005670 electromagnetic radiation Effects 0.000 description 1
- 230000000149 penetrating effect Effects 0.000 description 1
- 230000002093 peripheral effect Effects 0.000 description 1
- 238000005070 sampling Methods 0.000 description 1
- 238000012216 screening Methods 0.000 description 1
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Classifications
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01J—MEASUREMENT OF INTENSITY, VELOCITY, SPECTRAL CONTENT, POLARISATION, PHASE OR PULSE CHARACTERISTICS OF INFRARED, VISIBLE OR ULTRAVIOLET LIGHT; COLORIMETRY; RADIATION PYROMETRY
- G01J5/00—Radiation pyrometry, e.g. infrared or optical thermometry
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01J—MEASUREMENT OF INTENSITY, VELOCITY, SPECTRAL CONTENT, POLARISATION, PHASE OR PULSE CHARACTERISTICS OF INFRARED, VISIBLE OR ULTRAVIOLET LIGHT; COLORIMETRY; RADIATION PYROMETRY
- G01J5/00—Radiation pyrometry, e.g. infrared or optical thermometry
- G01J5/80—Calibration
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01J—MEASUREMENT OF INTENSITY, VELOCITY, SPECTRAL CONTENT, POLARISATION, PHASE OR PULSE CHARACTERISTICS OF INFRARED, VISIBLE OR ULTRAVIOLET LIGHT; COLORIMETRY; RADIATION PYROMETRY
- G01J5/00—Radiation pyrometry, e.g. infrared or optical thermometry
- G01J2005/0077—Imaging
Abstract
The invention discloses a point-by-point pixel error calibration method for an infrared module, and belongs to the technical field of temperature measurement. The method adopts an infrared module with the resolution of nxm to detect a constant temperature source with the temperature of T; each pixel position of the infrared module detects a constant temperature source and records the temperature, and then the temperature deviation of each pixel position is calculated and stored. The invention improves the accuracy and stability of temperature measurement of the infrared imaging human body surface temperature measurement system.
Description
Technical Field
The invention relates to the technical field of temperature measurement, in particular to a point-by-point pixel error calibration method for an infrared module.
Background
The infrared imaging module is a main device of an infrared imaging temperature measurement system, and a core component of the infrared imaging module is called a Focal Plane Array (FPA) and is similar to a CCD/CMOS chip. One micro scene element corresponds to one pixel on the array when sampling. The infrared focal plane array detector integrates the incident infrared energy and then converts the integrated infrared energy into an electrical signal for use by the controller. At present, due to the influence of multiple aspects such as manufacturing process, use environment, module lens, focal length adjustment and the like, even on a background with uniform temperature, output signals generated by all pixels in a focal plane background are inconsistent, namely the nonuniformity of an infrared focal plane array device.
From the production process, it is difficult and expensive to reduce the non-uniformity of the focal plane array simply from the viewpoint of improving the quality of the focal plane array. Therefore, most infrared imaging modules at home and abroad have the problems of low temperature measurement precision and unstable temperature measurement result, so that the infrared imaging modules have a large false alarm and misjudgment phenomenon in the aspects of medical treatment, prevention and control, epidemic prevention and other auxiliary screening, and the temperature measurement accuracy basically cannot meet the use requirement of medical grade. At present, most of temperature measurement systems adopting infrared imaging modules are mainly used in the middle area with better quality of a focal plane array in the market. The method does not realize effective utilization of pixels on the queue array, and cannot greatly improve the accuracy of temperature measurement.
Disclosure of Invention
In view of the above, the present invention provides a method for calibrating a pixel error point by point for an infrared module. The method improves the accuracy and stability of temperature measurement of the infrared imaging human body surface temperature measurement system.
In order to achieve the purpose, the technical scheme adopted by the invention is as follows:
a point-by-point pixel error calibration method for an infrared module comprises the following steps:
fixing an infrared module with the resolution of nxm on a high-precision holder, wherein n is more than or equal to 1, and m is more than or equal to 1;
placing a constant temperature source with the temperature of T in front of the infrared module, and detecting the constant temperature source through an infrared module, wherein T is more than or equal to 20 ℃ and less than or equal to 35 ℃;
rotating the holder to enable the constant-temperature source to form an image at each pixel position on a focal plane array detector of the infrared module, and recording the temperature t (x, y) at the pixel position (x, y) to obtain a temperature matrix A;
in the formula, x is more than or equal to 1 and less than or equal to m, and y is more than or equal to 1 and less than or equal to n;
step four, calculating the temperature deviation delta T (x, y) at the pixel position (x, y) to be T-T (x, y) according to the temperature T of the constant temperature source and the temperature T (x, y) at the pixel position (x, y), and outputting a temperature deviation matrix ADeviation of，
Step five, the deviation matrix ADeviation ofAnd storing the correction parameters of the infrared module.
The invention adopts the technical scheme to produce the beneficial effects that:
the invention adopts an error correction mode, detects and stores the correction parameters of the infrared module in advance, and improves the environmental adaptability and the temperature measurement precision of the infrared module.
Drawings
Fig. 1 is a schematic diagram of imaging of an infrared module in an embodiment of the invention.
FIG. 2 is a diagram illustrating horizontal shifting of thermometric pixel bits according to an embodiment of the present invention.
FIG. 3 is a schematic diagram of the vertical movement of the thermometric pixel bits in the embodiment of the present invention.
Detailed Description
The present invention will be further described with reference to the accompanying drawings and specific embodiments.
A point-by-point pixel error calibration method for an infrared module comprises the following steps:
fixing an infrared module with the resolution of nxm on a high-precision holder, wherein n is more than or equal to 1, and m is more than or equal to 1;
placing a constant temperature source with the temperature of T in front of the infrared module, and detecting the constant temperature source through an infrared module, wherein T is more than or equal to 20 ℃ and less than or equal to 35 ℃;
rotating the holder to enable the constant-temperature source to form an image at each pixel position on a focal plane array detector of the infrared module, and recording the temperature t (x, y) at the pixel position (x, y) to obtain a temperature matrix A;
in the formula, x is more than or equal to 1 and less than or equal to m, and y is more than or equal to 1 and less than or equal to n;
step four, calculating the temperature deviation delta T (x, y) at the pixel position (x, y) to be T-T (x, y) according to the temperature T of the constant temperature source and the temperature T (x, y) at the pixel position (x, y), and outputting a temperature deviation matrix ADeviation of，
Step five, the deviation matrix ADeviation ofAnd storing the correction parameters of the infrared module.
The following is a more specific example:
each pixel on the infrared module can be regarded as a non-contact temperature detector. An object whose temperature is above absolute zero emits electromagnetic radiation outwardly from its surface and this radiation is proportional to the intrinsic temperature of the object. After penetrating through the atmosphere, the radiation is collected on the detector through the lens of the infrared module. The detector then generates an electrical signal proportional to the radiation. The signal is amplified and converted into a detected temperature value.
Referring to fig. 1, in this embodiment, a constant temperature source is placed in front of the infrared module as the object to be measured. The temperature of the constant temperature source is T-25 ℃, and the energy radiated by the constant temperature source reaches the focal plane array detector in the infrared module through the lens.
The infrared imaging module is fixed on the high-precision holder, and the holder is controlled to rotate in the horizontal direction through instructions. When the holder rotates horizontally, the imaging position of the constant-temperature source on the focal plane array detector moves along the horizontal direction, referring to fig. 2.
Similarly, when the holder rotates up and down, the imaging position of the constant-temperature source on the focal plane array detector moves along the vertical direction, referring to fig. 3.
Through the mode, the imaging of the constant temperature source at any pixel position of the focal plane can be controlled by sending an instruction to the holder. When the constant temperature source is imaged at a certain pixel position (x, y) of the detector, the measured temperature of the position output by the detector is t (x, y). The resolution of the infrared module to be calibrated is N × M, that is to say, the scale of the infrared focal plane array is N × M. All pixel positions on the detector are measured one by one, and a temperature matrix can be output:
in the formula, x is more than or equal to 1 and less than or equal to m, and y is more than or equal to 1 and less than or equal to n;
since the temperature T of the constant temperature source of the measured object is constant, the temperature matrix A should theoretically be a constant value. However, due to the influence of various factors, the temperature of the central area of the array detector is relatively close in practical use, and the peripheral temperature has large error. Calculating the temperature deviation delta T at the pixel bit (x, y) as T-T according to the temperature T of the constant temperature source and the temperature T at the pixel bit (x, y), and outputting a temperature deviation matrix ADeviation of，
In the formula, Δ t (x, y) represents a temperature deviation at the pixel bit (x, y); x is more than or equal to 1 and less than or equal to m, and y is more than or equal to 1 and less than or equal to n;
practice proves that the deviation value of each pixel of the detector is basically not influenced by environmental factors. Therefore, the deviation array A can be usedDeviation ofStored as a constant and used as a calibration for the infrared moduleA positive parameter.
During actual use, an infrared radiation signal emitted by a human body or an object reaches a certain pixel of the infrared module, and the temperature value measured by the pixel has an error of delta t, so that the error can be automatically compensated through the control system, and the compensated temperature value can be regarded as the real temperature of the object.
The error correction method provided by the invention is used for carrying out a large amount of reliability verification in practical use. On the surface of a verification result, the error correction algorithm can effectively improve the environmental adaptability and the temperature measurement accuracy of the infrared module.
Claims (1)
1. A point-by-point pixel error calibration method for an infrared module is characterized by comprising the following steps:
fixing an infrared module with the resolution of nxm on a high-precision holder, wherein n is more than or equal to 1, and m is more than or equal to 1;
placing a constant temperature source with the temperature of T in front of the infrared module, and detecting the constant temperature source through an infrared module, wherein T is more than or equal to 20 ℃ and less than or equal to 35 ℃;
rotating the holder to enable the constant-temperature source to form an image at each pixel position on a focal plane array detector of the infrared module, and recording the temperature t (x, y) at the pixel position (x, y) to obtain a temperature matrix A;
in the formula, x is more than or equal to 1 and less than or equal to m, and y is more than or equal to 1 and less than or equal to n;
step four, calculating the temperature deviation delta T (x, y) at the pixel position (x, y) to be T-T (x, y) according to the temperature T of the constant temperature source and the temperature T (x, y) at the pixel position (x, y), and outputting a temperature deviation matrix ADeviation of，
Step five, the deviation matrixADeviation ofAnd storing the correction parameters of the infrared module.
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| CN202110508582.4A CN113252178A (en) | 2021-05-11 | 2021-05-11 | Point-by-point pixel error calibration method for infrared module |
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| CN202110508582.4A CN113252178A (en) | 2021-05-11 | 2021-05-11 | Point-by-point pixel error calibration method for infrared module |
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