CN112781724B - Detector non-uniformity real-time correction method, system and medium based on two-point method - Google Patents
Detector non-uniformity real-time correction method, system and medium based on two-point method Download PDFInfo
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Abstract
The invention provides a method, a system and a medium for correcting the nonuniformity of a detector in real time based on a two-point method, which relate to the technical field of terahertz imaging and comprise the following steps: step 1: adding a constant temperature device in the focal range of the detector; step 2: eliminating noise of the detector by adopting a multi-frame averaging method, storing multiple frames, then calculating an average value, and carrying out non-uniformity correction; and step 3: correcting each path of detector by using a two-point method, wherein the two reference values are the temperature of a high-temperature area and the temperature of a low-temperature area respectively; and 4, step 4: calculating the calibration result of each path of detector in real time, and solving the problem of drift of the detector caused by long-time operation; and 5: and judging whether the constant temperature device is shielded by the detected target in real time, and if the constant temperature device is shielded, not using the frame for correction calculation. The terahertz detector can improve the imaging quality of the detector, eliminates the influence of environmental temperature factors on terahertz imaging to the maximum extent, and does not reduce the imaging quality along with the long-time operation of the security detector.
Description
Technical Field
The invention relates to the technical field of terahertz imaging, in particular to a method, a system and a medium for correcting detector nonuniformity in real time based on a two-point method.
Background
As a section of electromagnetic spectrum resource which is not used by human beings in a large scale, the terahertz wave has extremely rich interaction effect between electromagnetic waves and substances, and has wide application prospect not only in the field of basic research but also in a plurality of technical fields such as security inspection imaging, radar, communication, astronomy, atmospheric observation, biomedicine and the like.
Due to the influences of factors such as unevenness of semiconductor materials for manufacturing devices, mask errors, defects and processes, the output amplitude of the terahertz detector is uneven, and due to the uneven existence of the unevenness, the obtained image signals are blurred and distorted, and have serious light and shade stripes, and even cannot be imaged. The conventional correction method is a one-point correction method, and the reference source is generally an imaging background.
For the prior art, the defect of the one-point correction method is that the farther from the correction point, the larger the residual nonuniformity after correction, and especially when larger noise exists, the problem is particularly obvious; the background is used as a reference source and is greatly influenced by the ambient temperature. In addition, if real-time correction is not performed, after long-time operation, a correction result diverges, and terahertz imaging quality is reduced.
Disclosure of Invention
Aiming at the defects in the prior art, the invention aims to provide a method, a system and a medium for correcting the nonuniformity of a detector in real time based on a two-point method, which can improve the imaging quality of the detector, eliminate the influence of environmental temperature factors on terahertz imaging to the greatest extent and prevent the imaging quality from being reduced along with the long-time running of a security check instrument.
According to the detector non-uniformity real-time correction method, system and medium based on the two-point method, the scheme is as follows:
in a first aspect, a two-point method-based detector non-uniformity real-time correction method is provided, and the method includes:
a constant temperature device is added in the focal length range of the detector and is divided into a high-temperature area and a low-temperature area, and the width of the constant temperature device is larger than the width of a view field of the detector;
eliminating noise of the detector by adopting a multi-frame averaging method, enabling the output value of the detector to be smoother, and after storing multiple frames, calculating an average value and carrying out non-uniformity correction;
correcting each path of detector by using a two-point method, wherein the two reference values are the temperature of a high-temperature area and the temperature of a low-temperature area respectively;
calculating the calibration result of each path of detector in real time, and solving the problem of drift of the detector caused by long-time operation;
and judging whether the constant temperature device is shielded by the detected target in real time, and if the judgment result is shielded, not using the frame for correction calculation.
Preferably, the step of eliminating noise of the detector by using a multi-frame averaging method includes:
firstly, the gain factor K is obtained according to the following formula i And offset b i ：
Wherein V i (1) Indicating the output value, V, of each detector in the low-temperature region i (2) The output values of all paths of detectors in the high-temperature area are represented, T1 represents the temperature value of the low-temperature area, and T2 represents the temperature value of the low-temperature area;
the gain factor K can be obtained by using the formula i And offset b i ，
Preferably, the step of calibrating each of the detectors by using a two-point method includes:
firstly, gain factor K is obtained i And offset b i ；
A gain factor K i And offset b i The multiplication and addition operations are performed on the detector output values.
In a second aspect, a two-point method based real-time detector nonuniformity correction system is provided, which includes:
module 1: a constant temperature device is added in the focal length range of the detector and is divided into a high temperature area and a low temperature area, and the width of the constant temperature device is larger than the width of a view field of the detector;
and (3) module 2: eliminating noise of the detector by adopting a multi-frame averaging method, enabling the output value of the detector to be smoother, and after storing multiple frames, calculating an average value and carrying out non-uniformity correction;
and a module 3: correcting each path of detector by using a two-point method, wherein the two reference values are the temperature of a high-temperature area and the temperature of a low-temperature area respectively;
and (4) module: calculating the calibration result of each path of detector in real time, and solving the problem of drift of the detector caused by long-time operation;
and a module 5: and judging whether the constant temperature device is shielded by the detected target in real time, and if the judgment result is shielded, not using the frame for correction calculation.
Preferably, the module 2 comprises:
firstly, the gain factor K is obtained according to the following formula i And offset b i ：
Wherein V i (1) Indicating the output value, V, of each detector in the low-temperature region i (2) The output values of all paths of detectors in the high-temperature area are represented, T1 represents the temperature value of the low-temperature area, and T2 represents the temperature value of the low-temperature area;
the gain factor K can be obtained by using the formula i And offset b i ，
Preferably, the module 3 comprises:
firstly, gain factor K is obtained i And offset b i ；
A gain factor K i And offset b i And multiplying and adding the output values of the detectors.
Compared with the prior art, the invention has the following beneficial effects:
1. the imaging quality of the detector is greatly improved;
2. the influence of environmental factors on terahertz imaging can be eliminated to the greatest extent;
3. the imaging quality is not reduced along with the long-time operation of the security check instrument.
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Other features, objects and advantages of the invention will become more apparent upon reading of the detailed description of non-limiting embodiments with reference to the following drawings:
fig. 1 is a view of a thermostat.
Detailed Description
The present invention will be described in detail with reference to specific examples. The following examples will assist those skilled in the art in further understanding the invention, but are not intended to limit the invention in any way. It should be noted that it would be obvious to those skilled in the art that various changes and modifications can be made without departing from the spirit of the invention. All falling within the scope of the present invention.
The embodiment of the invention provides a method for correcting the nonuniformity of a detector in real time based on a two-point method, which is shown in figure 1. The temperature in the high temperature zone is constant at 40 ℃ and the temperature in the low temperature zone is constant at 25 ℃.
Secondly, eliminating the noise of the detector by adopting a multi-frame averaging method to ensure that the detector is in a noise-free stateThe output value is smoother, after a plurality of frames, such as 180 frames, are stored, then the average value is calculated, and the non-uniformity correction is carried out. Firstly, the gain factor K is obtained according to the following formula i And offset b i ：
Wherein V i (1) The output values of all the detectors in the low-temperature area are represented; v i (2) Representing the output values of all paths of detectors in the high-temperature area; t1 represents the temperature value of the low temperature zone, which is constant at 25 ℃ in the present embodiment; t2 represents a temperature value of the low temperature region, which is constant at 40 ℃ in this embodiment. The gain factor K can be obtained according to the formula i And offset b i ：
And correcting each path of detector by using a two-point method, wherein the two reference values are the temperature of a high-temperature area and the temperature of a low-temperature area respectively. The method can reduce the dependence of the detector on the ambient temperature to the maximum extent, so that the detection effect can be optimal under different ambient temperatures.
Gain factor K is obtained through calculation i And offset b i And then, calculating the calibration result of each path of detector in real time, and solving the problem that the detector drifts when running for a long time. And finally, the detected target possibly shields the constant temperature device after entering the field of view of the security check instrument, the method can judge whether the constant temperature device is shielded by the detected target in real time, if the judgment result is shielded, the frame is not used for correction calculation, and real-time correction can be carried out simultaneously with security check without influencing the correction accuracy.
The embodiment of the invention provides a two-point method-based detector non-uniformity real-time correction method, which can greatly improve the imaging quality of a detector, can eliminate the influence of environmental factors on terahertz imaging to the greatest extent, and can not reduce the imaging quality along with the long-time running of a security inspection instrument.
Those skilled in the art will appreciate that, in addition to implementing the system and its various devices, modules, units provided by the present invention as pure computer readable program code, the system and its various devices, modules, units provided by the present invention can be fully implemented by logically programming method steps in the form of logic gates, switches, application specific integrated circuits, programmable logic controllers, embedded microcontrollers and the like. Therefore, the system and various devices, modules and units thereof provided by the invention can be regarded as a hardware component, and the devices, modules and units included in the system for realizing various functions can also be regarded as structures in the hardware component; means, modules, units for performing the various functions may also be regarded as structures within both software modules and hardware components for performing the method.
The foregoing description of specific embodiments of the present invention has been presented. It is to be understood that the present invention is not limited to the specific embodiments described above, and that various changes or modifications may be made by one skilled in the art within the scope of the appended claims without departing from the spirit of the invention. The embodiments and features of the embodiments of the present application may be combined with each other arbitrarily without conflict.
Claims (3)
1. A two-point method-based detector nonuniformity real-time correction method is characterized by comprising the following steps:
step 1: a constant temperature device is added in the focal length range of the detector and is divided into a high-temperature area and a low-temperature area, and the width of the constant temperature device is larger than the width of a view field of the detector;
step 2: eliminating noise of the detector by adopting a multi-frame averaging method, enabling the output value of the detector to be smoother, and after storing multiple frames, calculating an average value and carrying out non-uniformity correction;
and step 3: correcting each path of detector by using a two-point method, wherein the two reference values are the temperature of a high-temperature area and the temperature of a low-temperature area respectively;
and 4, step 4: calculating the calibration result of each path of detector in real time, and solving the problem of drift of the detector caused by long-time operation;
and 5: judging whether the constant temperature device is shielded by the detected target in real time, and if the judgment result is that the constant temperature device is shielded, not using the frame for correction calculation;
the step 2 comprises the following steps:
firstly, the gain factor K is obtained according to the following formula i And offset b i ：
Wherein V i (1) Indicating the output value, V, of each detector in the low-temperature region i (2) The output values of all paths of detectors in the high-temperature area are represented, T1 represents the temperature value of the low-temperature area, and T2 represents the temperature value of the low-temperature area;
the gain factor K can be obtained by using the formula i And offset b i ，
The step 3 comprises the following steps:
step 3-1: first, gain factor K is obtained i And offset b i ；
Step 3-2: a gain factor K i And offset b i Multiplying and adding the output values of the detectors;
the detector is a terahertz detector.
2. A two-point method based detector non-uniformity real-time correction system, the system comprising:
module 1: a constant temperature device is added in the focal length range of the detector and is divided into a high-temperature area and a low-temperature area, and the width of the constant temperature device is larger than the width of a view field of the detector;
and (3) module 2: eliminating noise of the detector by adopting a multi-frame averaging method, enabling the output value of the detector to be smoother, and after storing multiple frames, calculating an average value and carrying out non-uniformity correction;
and a module 3: correcting each path of detector by using a two-point method, wherein the two reference values are the temperature of a high-temperature area and the temperature of a low-temperature area respectively;
and a module 4: calculating the calibration result of each path of detector in real time, and solving the problem of drift of the detector caused by long-time operation;
and a module 5: judging whether the constant temperature device is shielded by the detected target in real time, and if the judgment result is that the constant temperature device is shielded, not using the frame for correction calculation;
the module 2 comprises:
firstly, the gain factor K is obtained according to the following formula i And offset b i ：
Wherein V i (1) Indicating the output value, V, of each detector in the low-temperature region i (2) The output values of all paths of detectors in the high-temperature area are represented, T1 represents the temperature value of the low-temperature area, and T2 represents the temperature value of the low-temperature area;
the gain factor K can be obtained by using the formula i And offset b i ，
The module 3 comprises:
firstly, gain factor K is obtained i And offset b i ；
A gain factor K i And offset b i Multiplying and adding the output values of the detectors;
the detector is a terahertz detector.
3. A computer-readable storage medium, in which a computer program is stored which, when being executed by a processor, carries out the steps of the method as claimed in claim 1.
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| CN108240863A (en) * | 2016-12-23 | 2018-07-03 | 南京理工大学 | For real-time 2 asymmetric correction methods of Uncooled infrared camera |
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| IL173418A (en) * | 2006-01-29 | 2013-10-31 | Rafael Advanced Defense Sys | Non-uniformity correction of images generated by focal plane arrays of photodetectors |
| US9936106B2 (en) * | 2015-11-12 | 2018-04-03 | Sensors Unlimited, Inc. | Pixel non-uniformity correction |
| CN106644078A (en) * | 2016-12-30 | 2017-05-10 | 电子科技大学 | Terahertz image non-uniformity correction method |
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| CN105466563A (en) * | 2014-09-09 | 2016-04-06 | 南京理工大学 | Infrared thermal imager inhomogeneity two-point correction module and method |
| CN108240863A (en) * | 2016-12-23 | 2018-07-03 | 南京理工大学 | For real-time 2 asymmetric correction methods of Uncooled infrared camera |
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| 红外焦平面阵列响应度非均匀性的校正算法;蔡建荣等;《红外》;20070228;第28卷(第2期);全文 * |
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