CN104729718A - Processing system and method used for NETD of infrared imaging system - Google Patents

Abstract

The invention relates to a processing system and method used for an NETD of an infrared imaging system. The processing system comprises a parameter setting module, a data collecting module, an image display module, a state display module, an NETD computing module, a storage module and the like. The parameter setting module is used for setting a temperature value of a standard radiation source, collecting frequency N and a random pixel number M. The data collecting module is used for collecting data, and the storage module is used for storing the data. The computing module is mainly used for computing an average gray-value, mean-square noise and the NETD of the collected data. The state display module is used for displaying a current running state. The image display module is used for displaying a current grayscale image. According to the processing system and method, the NETD of the infrared imaging system can be obtained without complex NETD testing equipment or professional operating staff.

Description

A kind of disposal system for infrared imaging system NETD and method

Technical field

The invention belongs to infrared imaging system field tests, relate to a kind of disposal system for infrared imaging system NETD (noise equivalent temperature difference) and method.

Background technology

The performance parameter of laboratory evaluation infrared imaging system, can be divided into two classes: i.e. subjective performance parameter, and they are obtained by eye-observation by observer, comprises minimum resolvable temperature difference (MRTD) and minimum detectable temperature difference (MDTD); Another kind of is objective performance parameter, it is obtained by actinometry or electric parameter measurement, there is the parameter of reflected signal transmission characteristic (as signal transmission, spectrum transmission, geometry transmission, strong signal response, LF-response, system time response), the parameter (as modulation transfer function, phase transfer function) of reflection optical transfer characteristic, the parameter (as noise equivalent temperature difference NETD, spatial non-uniformity) etc. of reflection noise equivalent characteristic.NETD (noise equivalent temperature difference) is the important objective evaluation index of thermal imaging system sensitivity, can be used for the detection range predicting little temperature difference point target, thus the conversion of actualizing technology mark sense tactics index.MRTD is the subjective assessment standard of thermal imaging system sensitivity and resolution.NETD and MRTD is the topmost performance evaluation parameters of current thermal imaging system, because MRTD test is completed by four bar targets on eye-observation monitor.The impact of test person subjective factor is subject in test process.Must be undertaken by the several personnel through professional training.Thus the NETD as objective examination's parameter is more approved.

NETD is system when observing test pattern, and the peak signal that reference electronic filter output produces and root mean square noise are than the temperature difference of black matrix object and background in standard test images when being 1.According to definition, the measured equation of NETD is:

$\mathrm{NETD}=\frac{\mathrm{\ΔT}}{\mathrm{Vs}/\mathrm{Vn}}---\left(1\right)$

In formula, Δ T is the temperature difference of object and background; Vs is signal voltage value; Vn is root mean square noise.

At present, the acquisition pattern of NETD has two kinds, and one is theory calculate, and another kind uses special testing apparatus to carry out system testing.Wherein the formula of theory calculate employing is such as formula shown in (2):

$\mathrm{NETD}=\frac{4F^2}{{\left(2A_d{\mathrm{\τ}}_d\right)}^{1/2}{\mathrm{\τ}}_a{\mathrm{\τ}}_0{D}^{*}(\mathrm{\ΔM}/\mathrm{\ΔT})}---\left(2\right)$

In formula: F is optical system F number; A _dfor the area of single pixel; τ _dfor the residence time of detector; τ _afor atmospheric transmittance; τ ₀for optical transmittance; D ^*for detector spectrum detectivity; Δ M/ Δ T is differential radiancy.Because the method relates to numerous parameters of system transmission characteristic, so be a kind of theoretic computing method, still there is certain error with the measurement of reality.

The measuring method using special test equipment infrared imaging system is placed in effective image-forming range, parallel light tube, black matrix, target, image data processing software is utilized to test, Fig. 2 is exactly the composition frame chart of special test equipment, the method is real measuring method, but need special testing apparatus and tester and enough spaces, particularly when infrared imaging system volume is larger, test bothers very much, and dirigibility is not strong.

Summary of the invention

The technical matters that the present invention solves is: overcome prior art deficiency, a kind of disposal system for infrared imaging system noise equivalent temperature difference and method are proposed, a kind of method of testing of new noise equivalent temperature difference is found between theory calculate and special test equipment, the noise equivalent temperature difference calculating infrared imaging system that can be authentic and valid, do not need again special test to survey standby, just can complete in laboratory.Thus realize its dirigibility, versatility.

The present invention includes following technical scheme: a kind of disposal system and method being used for infrared imaging system NETD (noise equivalent temperature difference), comprises parameter setting module, data acquisition module, image display, state display module, NETD computing module, storage module;

Parameter setting module, is used for arranging the number M of the temperature value of calibrated radiation source, systemic resolution, times of collection N, stochastic sampling point;

When Standard Ratio source temperature to be set to T1, to stablize to T1 until state display module displays temperature by parameter setting module, gather the two-dimensional image data of first group of N radiation source and be stored in storage module, showing the gray level image of first group of N radiation source simultaneously in image display;

The view data of data collecting module collected first group of N radiation source, and the average gray value Vs1 of a certain pixel and mean square noise Vn1 in the view data stochastic sampling point M of this first group of N the radiation source calculated in view data according to this first group of N radiation source, then current operation is repeated, until calculate M stochastic sampling point average gray value and mean square noise, and shown by state display module;

When Standard Ratio source temperature is set to T2 by parameter setting module, and T2 > T1, stablize to T2 until state display module displays temperature, gather the two-dimensional image data of second group of N radiation source and be stored in storage module, showing the gray level image of second group of N radiation source simultaneously in image display;

The view data of data collecting module collected second group of N radiation source, and the average gray value Vs2 of a certain pixel and mean square noise Vn2 in the view data stochastic sampling point M of this second group of N the radiation source calculated in view data according to this second group of N radiation source, then current operation is repeated, until calculate M stochastic sampling point average gray value and mean square noise, and shown by state display module;

NETD computing module, according to noise equivalent temperature difference computing formula NETD=△ T/ (△ Vs/ △ Vn), calculate the noise equivalent temperature difference of this stochastic sampling point, in formula, △ T is the value of T2-T1, and △ Vs is the value of Vs2-Vs1, and △ Vn is the value of Vn2-Vn1;

Averaging to the NETD of M stochastic sampling point, is exactly the NETD of system, and shows final result of calculation.

A kind of disposal route being used for infrared imaging system NETD (noise equivalent temperature difference), comprises the following steps:

(1) Standard Ratio source temperature is set to T1, times of collection is set to N, the number of stochastic sampling point is set to M;

(2) after temperature stabilization to T1, gather the two-dimensional image data of N radiation source and store;

(3) view data of N the radiation source preserved by step (2), the average gray value Vs1 of a certain pixel and mean square noise Vn1 in view data M sampled point of calculation procedure (2) N radiation source, then current operation is repeated, until calculate M stochastic sampling point average gray value and mean square noise;

(4) Standard Ratio source temperature is set to T2, and T2 > T1, after temperature stabilization to T2, gather the view data of N radiation source and store;

(5) view data of N the radiation source preserved by step (4), the average gray value Vs2 of a certain pixel and mean square noise Vn2 in view data M sampled point of calculation procedure (4) N radiation source, then current operation is repeated, until calculate M stochastic sampling point average gray value and mean square noise;

(6) according to noise equivalent temperature difference computing formula NETD=△ T/ (△ Vs/ △ Vn), calculate the noise equivalent temperature difference of this sampled point, in formula, △ T is the value of T2-T1, and △ Vs is the value of Vs2-Vs1, and △ Vn is the value of Vn2-Vn1;

(7) NETD of multi-point sampling is averaged, obtain the noise equivalent temperature difference NETD of infrared imaging system to be measured.

Described N is 0 to 128, M is 0 to 32, can improve arithmetic speed, effectively can reduce statistical error again, improves measuring accuracy.

The present invention's beneficial effect is compared with prior art:

(1) method of testing of infrared imaging system noise equivalent temperature difference mainly uses large-scale special test equipment to measure at present, as the test products of SBIR, EOI company of the U.S., French HGH company, CI company of Israel, need the operating personnel etc. of special software for calculation and special test site and specialty, and testing cost is higher, the present invention does not need the operating personnel of special test site and specialty, only need the blackbody radiation source of standard just can complete in laboratory, substantially do not need extra cost.

(2) the present invention derives in the definition of noise equivalent temperature difference, by effective demarcation of black-body reference and choosing flexibly of random point, particularly multiple spot is averaged, and effectively can reduce error, makes result of calculation more close to the actual value of noise equivalent temperature difference.

(3) the present invention compares with complicated theory calculate, there is operability and authenticity, because theory calculate needs to relate to the parameter such as atmospheric transmittance, differential radiancy, all need just can provide under given conditions, major part is the valuation under certain condition, this just brings very large error to theory calculate, so reference when theory calculate can only be system.

(4) algorithm of the present invention is simple, easy to use, does not need the training of specialty just can operate, is more suitable for promotion and application.

Accompanying drawing explanation

Fig. 1 is the workflow diagram of the present invention for infrared imaging system noise equivalent temperature difference computing method;

Fig. 2 is large-scale dedicated testing platform;

Fig. 3 is test platform of the present invention;

Fig. 4 is NETD computing system composition frame chart of the present invention.

Embodiment

Just by reference to the accompanying drawings specific embodiment of the invention is further described below:

The present invention proposes a kind of disposal system for infrared imaging system NETD (noise equivalent temperature difference) and method, and the method in the abundant current existing method of testing of contrast, draws by constantly summing up and putting into practice.In order to complete the calculating of noise equivalent temperature difference, need to build a set of test platform, this platform specifically comprises standard black body radiation source, focal plane subassembly, image capturing system, and its composition frame chart as shown in Figure 3.

Fig. 4 is NETD disposal system composition frame chart of the present invention, and it comprises parameter setting module, data acquisition module, image display, state display module, NETD computing module, storage module.

Parameter setting module comprises resolution setting, sampling number N is arranged, stochastic sampling point number M is arranged, temperature is arranged, and its intermediate-resolution arranges the resolution being used for arranging current infrared imaging system, form: x × y; Times of collection N arranges the number of times being used for arranging each temperature value and will gathering; Stochastic sampling number M arranges and is used for arranging the current pixel number that will gather, and is provided with rear system and automatically can selects the individual random pixel of M, such as pixel 6, pixel 9, pixel 33 etc.; Temperature arranges and is used for arranging the current temperature value that will gather.Whether the temperature that simultaneously state display module can show setting is stablized, by data acquisition module, current temperature is gathered after stable, image display shows current gray level image, average gray value and the mean square noise of rear direct calculating M stochastic sampling point are gathered, and show result of calculation stored in storage module by state display module, repeat aforesaid operations once, the last NETD being drawn infrared imaging system by NETD computing module by the mean value getting M collection point, and result of calculation is shown in state display module.

Specific works flow process of the present invention is as shown in Figure 1:

When Standard Ratio source temperature to be set to T1, to stablize to T1 until state display module displays temperature by parameter setting module, gather the two-dimensional image data of first group of N radiation source and be stored in storage module, showing the gray level image of first group of N radiation source simultaneously in image display;

The view data of data collecting module collected first group of N radiation source, and the average gray value Vs1 of a certain pixel and mean square noise Vn1 in the view data stochastic sampling point M of this first group of N the radiation source calculated in view data according to this first group of N radiation source, then current operation is repeated, until calculate M stochastic sampling point average gray value and mean square noise, and shown by state display module:

If the gray-scale value of different images data same point (i, j) (0<i≤x, 0<j≤y) is respectively Vs1 _ijT1, Vs2 _ijT1, Vs3 _ijT1vsN _ijT1, in computed image data certain some the average gray value of (i, j) and mean square noise be respectively:

$\stackrel{\&OverBar;}{{\mathrm{Vs}}_{\mathrm{ijT}1}}=\frac{{\mathrm{Vs}1}_{\mathrm{ijT}1}+{\mathrm{Vs}2}_{\mathrm{ijT}1}+{\mathrm{Vs}3}_{\mathrm{ijT}1}......+{\mathrm{VsN}}_{\mathrm{ijT}1}}{N}$

${\mathrm{Vn}}_{\mathrm{ijT}1}=\frac{1}{N}\sqrt{{({\mathrm{Vs}1}_{\mathrm{ijT}1}-{\mathrm{Vs}}_{\mathrm{ijT}1})}^2+{({\mathrm{Vs}2}_{\mathrm{ijT}1}-{\mathrm{Vs}}_{\mathrm{ijT}1})}^2......+{({\mathrm{VsN}}_{\mathrm{ijT}1}-{\mathrm{Vs}}_{\mathrm{ijT}1})}^2}$

When Standard Ratio source temperature is set to T2 by parameter setting module, and T2 > T1, stablize to T2 until state display module displays temperature, gather the two-dimensional image data of second group of N radiation source and be stored in storage module, showing the gray level image of second group of N radiation source simultaneously in image display;

The view data of data collecting module collected second group of N radiation source, and the average gray value Vs2 of a certain pixel and mean square noise Vn2 in the view data stochastic sampling point M of this second group of N the radiation source calculated in view data according to this second group of N radiation source, then current operation is repeated, until calculate M stochastic sampling point average gray value and mean square noise, and shown by state display module:

If the gray-scale value of different images data same point (i, j) is respectively Vs1 _ijT2, Vs2 _ijT2, Vs3 _ijT2vsN _ijT2, in computed image data certain some the average gray value of (i, j) and mean square noise be respectively:

$\stackrel{\&OverBar;}{{\mathrm{Vs}}_{\mathrm{ijT}2}}=\frac{{\mathrm{Vs}1}_{\mathrm{ijT}2}+{\mathrm{Vs}2}_{\mathrm{ijT}2}+{\mathrm{Vs}3}_{\mathrm{ijT}2}......+{\mathrm{VsN}}_{\mathrm{ijT}2}}{N}$

${\mathrm{Vn}}_{\mathrm{ijT}2}=\frac{1}{N}\sqrt{{({\mathrm{Vs}1}_{\mathrm{ijT}2}-{\mathrm{Vs}}_{\mathrm{ijT}2})}^2+{({\mathrm{Vs}2}_{\mathrm{ijT}2}-{\mathrm{Vs}}_{\mathrm{ijT}2})}^2......+{({\mathrm{VsN}}_{\mathrm{ijT}2}-{\mathrm{Vs}}_{\mathrm{ijT}2})}^2}$

Then, calculate the noise equivalent temperature difference of this point, and show in state display module:

${\mathrm{NETD}}_{\mathrm{ij}}=\frac{T2-T1}{(\stackrel{\&OverBar;}{{\mathrm{Vs}}_{\mathrm{ijT}2}}-\stackrel{\&OverBar;}{{\mathrm{Vs}}_{\mathrm{ijT}1}})/\frac{{\mathrm{Vn}}_{\mathrm{ijT}1}+{\mathrm{Vn}}_{\mathrm{ijT}2}}{2}}=\frac{(T2-T1)\&times;({\mathrm{Vn}}_{\mathrm{ijT}1}+{\mathrm{Vn}}_{\mathrm{ijT}2})}{2(\stackrel{\&OverBar;}{{\mathrm{Vs}}_{\mathrm{ijT}2}}-\stackrel{\&OverBar;}{{\mathrm{Vs}}_{\mathrm{ijT}1}})}$

Finally, calculating the noise equivalent temperature difference that the noise equivalent temperature difference of M difference is averaged the system of obtaining is:

$\mathrm{NETD}=\frac{{\mathrm{NETD}}_{\mathrm{ij}}+{\mathrm{NETD}}_{\mathrm{kh}}+......{\mathrm{NETD}}_{\mathrm{uv}}}{M}$

Wherein NETD _ij, NETD _kh, NETD _uvthe noise equivalent temperature difference of difference, and 0<i≤x, 0<j≤y; 0<k≤x, 0<h≤y; 0<u≤x, 0<v≤y.

In the disposal route of the above-mentioned noise equivalent temperature difference for infrared imaging system, N is the integer of 0 to 128, and M is the integer of 0 to 32.

The above; be only the embodiment of the best of the present invention, but this bright protection domain is not limited thereto, is anyly familiar with those skilled in the art in the technical scope of this bright exposure; the change that can expect easily and replacement, all should be encompassed within protection scope of the present invention.

The unspecified part of the present invention belongs to general knowledge as well known to those skilled in the art.

Claims (3)

1. for a disposal system of infrared imaging system NETD, it is characterized in that: comprise parameter setting module, data acquisition module, image display, state display module, NETD computing module, storage module;

Parameter setting module, is used for arranging the number M of the temperature value of calibrated radiation source, systemic resolution, times of collection N, stochastic sampling point;

When Standard Ratio source temperature to be set to T1, to stablize to T1 until state display module displays temperature by parameter setting module, gather the two-dimensional image data of first group of N radiation source and be stored in storage module, showing the gray level image of first group of N radiation source simultaneously in image display;

The view data of data collecting module collected first group of N radiation source, and the average gray value Vs1 of a certain pixel and mean square noise Vn1 in the view data stochastic sampling point M of this first group of N the radiation source calculated in view data according to this first group of N radiation source, then current operation is repeated, until calculate M stochastic sampling point average gray value and mean square noise, and shown by state display module;

When Standard Ratio source temperature is set to T2 by parameter setting module, and T2 > T1, stablize to T2 until state display module displays temperature, gather the two-dimensional image data of second group of N radiation source and be stored in storage module, showing the gray level image of second group of N radiation source simultaneously in image display;

The view data of data collecting module collected second group of N radiation source, and the average gray value Vs2 of a certain pixel and mean square noise Vn2 in the view data stochastic sampling point M of this second group of N the radiation source calculated in view data according to this second group of N radiation source, then current operation is repeated, until calculate M stochastic sampling point average gray value and mean square noise, and shown by state display module;

NETD computing module, according to noise equivalent temperature difference computing formula NETD=△ T/ (△ Vs/ △ Vn), calculate the noise equivalent temperature difference of this stochastic sampling point, in formula, △ T is the value of T2-T1, and △ Vs is the value of Vs2-Vs1, and △ Vn is the value of Vn2-Vn1;

Averaging to the NETD of M stochastic sampling point, is exactly the NETD of system, and shows final result of calculation.

2. for a disposal route of infrared imaging system NETD, it is characterized in that: comprise the following steps:

(1) Standard Ratio source temperature is set to T1, times of collection is set to N, the number of stochastic sampling point is set to M;

(2) after temperature stabilization to T1, gather the two-dimensional image data of N radiation source and store;

(3) view data of N the radiation source preserved by step (2), the average gray value Vs1 of a certain pixel and mean square noise Vn1 in view data M sampled point of calculation procedure (2) N radiation source, then current operation is repeated, until calculate M stochastic sampling point average gray value and mean square noise;

(4) Standard Ratio source temperature is set to T2, and T2 > T1, after temperature stabilization to T2, gather the view data of N radiation source and store;

(5) view data of N the radiation source preserved by step (4), the average gray value Vs2 of a certain pixel and mean square noise Vn2 in view data M sampled point of calculation procedure (4) N radiation source, then current operation is repeated, until calculate M stochastic sampling point average gray value and mean square noise;

(6) according to noise equivalent temperature difference computing formula NETD=△ T/ (△ Vs/ △ Vn), calculate the noise equivalent temperature difference of this sampled point, in formula, △ T is the value of T2-T1, and △ Vs is the value of Vs2-Vs1, and △ Vn is the value of Vn2-Vn1;

(7) NETD of multi-point sampling is averaged, obtain the noise equivalent temperature difference NETD of infrared imaging system to be measured.

3. a kind of disposal route for infrared imaging system NETD as claimed in claim 2, it is characterized in that: in described step (5), N is 0 to 128, M is 0 to 32, can improve arithmetic speed, effectively can reduce statistical error again, improve measuring accuracy.