CN104580894A - Multi-point correction method and system for infrared focal plane - Google Patents

Abstract

The invention belongs to the technical field of image processing, and particularly relates to a multi-point correction method for an infrared focal plane. The method comprises steps as follows: step 1, an infrared focal plane detector acquires images of different temperature black bodies at the working temperature in every other 5 DEG C and uses the images as background images; step 2, a shutter is started, a related parameter of a shutter image is acquired, and a shutter correction parameter is acquired with the following formula shown in the specification according to the background images, wherein delta O is the shutter correction parameter, the related parameter of the shutter image comprises the mean value Xs of a shutter image Xs and the shutter image, Bi is the i<th> background image, Bi is the mean value of the background images, Ks is a gain correction parameter corresponding to the shutter image, and Ks is the mean value of the Ks; step 3, according to the shutter correction parameter delta O, a gain correction parameter K and a bias correction parameter Bj which correspond to an object image are introduced into the following formula shown in the specification for two-point correction, and a corrected image Y is calculated, wherein X is the to-be-corrected image, Y is the corrected image, delta O is the shutter correction parameter, Bj is the j<th> background image, and K is the gain correction image.

Description

A kind of multi-point correcting method of infrared focus plane and system

Technical field

The invention belongs to technical field of image processing, particularly relate to a kind of multi-point correcting method and system of infrared focus plane.

Background technology

Infrared focal plane array image-forming system is highly sensitive owing to having, volume is little, compact conformation, operating distance is far away, anti-interference good, penetrate flue dust haze ability strong, can the advantage such as all weather operations, become the trend of Development of Infrared Thermal Imaging Technology, and gazing type infrared focal plane array the main flow sensitive detection parts of following infra-red thermal imaging system development are become.

Based on these excellent features of infrared imaging system, it has been widely used in various military affairs (as early warning, detecting and tracking, Imaging Guidance etc.) and civil (as scientific research, remote sensing, industry monitoring, medical science etc.) field.Infrared Detectors is exactly a kind of device sightless infrared emanation being converted into visible or measurable signal, and it is one of element of most critical in infrared system.Large-scale infrared focal plane array device is a class infrared detector the most advanced now, is the class Infrared Detectors all given priority to both at home and abroad.Infrared focal plane array has the function to sensitive for infrared radiation and signal transacting simultaneously, the response signal of probe units all in device can be converted to orderly picture signal export by the reading circuit of device.And the existence of infrared focal plane array heterogeneity greatly reduces temperature resolution and the image quality of imaging system, therefore concerning high-quality infra-red thermal imaging system, Nonuniformity Correction is one of the most key image processing techniques.

But, there is diversified infrared focal plane array heterogeneity bearing calibration at home and abroad, two large classes roughly can be divided into based on reference source and the Nonuniformity Correction based on scene according to the method difference that correction coefficient obtains.A wherein point calibration, two point correction and Supplements etc. are that maturation is also the class correcting algorithm the most generally used the most based on the correcting algorithm of reference source, but these algorithms are only applicable to the linear response district detected, nonlinear response regional correction is all subject to the impact of infrared focal plane array image-forming mission nonlinear response, when the change of the ambient temperature of infrared focal plane array image-forming system and working temperature, the operating state of infrared focal plane array device also changes thereupon, calibration result will be deteriorated, thus affect Nonuniformity Correction precision, usual needs are periodically calibrated, and not there is adaptively correcting ability, therefore be difficult to tackle environment complicated and changeable.

Summary of the invention

The object of the present invention is to provide a kind of multi-point correcting method of infrared focus plane, be intended to solve existing infrared focal plane array and there is intrinsic heterogeneity, namely when identical homogeneous radiation inputs, the response of each probe unit of infrared focal plane array exports inconsistent.And conventional at present a point calibration, two point correction and Supplements, all be subject to the impact of infrared focal plane array image-forming mission nonlinear response, when the change of the ambient temperature of infrared focal plane array image-forming system and working temperature, the operating state of infrared focal plane array device also changes thereupon, causes the precision of correction and ability to be all deteriorated.

The technical scheme that the present invention solves the problems of the technologies described above is as follows: a kind of multi-point correcting method of infrared focus plane, comprises the steps:

Step 1, infrared focal plane detector, in operating temperature range, gathers the image image as a setting of different temperatures black matrix every 5 DEG C;

Step 2, starts shutter, obtains shutter image relevant parameter, and is inserted in following formula acquisition shutter corrected parameter according to background image,

$\mathrm{\&Delta;O}=(X_s-B_i)-({\stackrel{\&OverBar;}{X}}_s-{\stackrel{\&OverBar;}{B}}_i)\&times;\frac{\stackrel{\&OverBar;}{K_s}}{K_s}$

Wherein, Δ O is shutter corrected parameter, B _ithe i-th width background image, be the average of background image, shutter image relevant parameter comprises shutter image X _swith the average of shutter image k _sthe gain calibration parameter that shutter image is corresponding, k _saverage;

Step 3, according to shutter corrected parameter Δ O, introduces target image corresponding gain calibration parameter K and bias correction parameter B _jput school and carry out two point correction, substitute into following formula, image Y after calculation correction,

Wherein, X is the image of precorrection, and Y is the image after correcting, and Δ O is shutter corrected parameter, B _jbe jth width background image, K is gain calibration parameter.

On the basis of technique scheme, the present invention can also do following improvement.

Further, in described step 1, the scope of working temperature is-20 DEG C ~ 80 DEG C.

Further, details are as follows for described step 1:

The temperature of described black matrix covers the temperature range of detector Observable scene, temperature interval every 5 DEG C from low to high, background image is corresponding B respectively ₁, B ₂, B ₃... B _n, the average of background image is respectively $\stackrel{\&OverBar;}{B_1},\stackrel{\&OverBar;}{B_2},$ $\stackrel{\&OverBar;}{B_3},\&CenterDot;\&CenterDot;\&CenterDot;\&CenterDot;\&CenterDot;\&CenterDot;\stackrel{\&OverBar;}{B_n},$ And $\stackrel{\&OverBar;}{B_1}<\stackrel{\&OverBar;}{B_2}<\stackrel{\&OverBar;}{B_3}<\&CenterDot;\&CenterDot;\&CenterDot;\&CenterDot;\&CenterDot;\&CenterDot;<\stackrel{\&OverBar;}{B_n}.$

Further, the gain calibration parameter K that in described step 2, shutter image is corresponding _s, be specially:

When shutter timing determines place temperature range, obtain the image X of shutter _s, and calculate the average of shutter image relatively with the average of background image, determine be positioned at interval the bias correction parameter that then shutter image is corresponding is B _i, the gain calibration parameter that shutter image is corresponding is $K_s=({\stackrel{\&OverBar;}{B}}_{i+1}-{\stackrel{\&OverBar;}{B}}_i)/(B_{i+1}-B_i).$

Further, described step 2 specifically also comprises:

To shutter image X _scarry out two point correction, obtain shutter image X _simage Δ Y after two point correction _s, then Y _s=(X _s-B _i) × K _s; Wherein, B _ithe i-th width background image, and according to image Δ Y after two point correction _sobtain the offset Δ Y after correcting _s, wherein, y _saverage; Substitute into following formula, calculate shutter corrected parameter Δ O:

$\mathrm{\&Delta;O}=\frac{\mathrm{\&Delta;}{Y}_S}{K_s}$ Be transformed to $\mathrm{\&Delta;O}=(X_s-B_i)-({\stackrel{\&OverBar;}{X}}_s-{\stackrel{\&OverBar;}{B}}_i)\&times;\frac{\stackrel{\&OverBar;}{K_s}}{K_s}$

In formula, Δ O is shutter corrected parameter, Δ Y _sfor the image after two point correction, K _sfor the gain calibration parameter that shutter image is corresponding, k _saverage, X _sfor shutter image, for the average of shutter image, B _ithe i-th width background image, it is the average of background image.

Further, described step 3 specifically comprises as follows:

According to the target image place temperature range of precorrection, calculate the average of target image relatively with the average of background image, determine be positioned at interval bias correction parameter then corresponding to target image is B _j, gain calibration parameter is then, two point correction is carried out to target image, substitutes into following formula, image Y after calculation correction:

Wherein, X is the image of precorrection, and Y is the image after correcting, and Δ O is shutter corrected parameter, B _jbe jth width background image, K is gain calibration parameter.

Another object of the present invention is to the system of the Supplements that a kind of infrared focus plane is provided, comprising:

Collecting unit, in operating temperature range, gathers the image image as a setting of different temperatures black matrix every 5 DEG C;

Computing unit, for starting shutter, obtains shutter image relevant parameter, and is inserted in following formula acquisition shutter corrected parameter according to background image,

$\mathrm{\&Delta;O}=(X_s-B_i)-({\stackrel{\&OverBar;}{X}}_s-{\stackrel{\&OverBar;}{B}}_i)\&times;\frac{\stackrel{\&OverBar;}{K_s}}{K_s}$

Wherein, Δ O is shutter corrected parameter, B _ithe i-th width background image, be the average of background image, shutter image relevant parameter comprises shutter image X _swith the average of shutter image k _sthe gain calibration parameter that shutter image is corresponding, k _saverage;

Correcting unit, for according to shutter corrected parameter Δ O, introduces target image corresponding gain calibration parameter K and bias correction parameter B _jput school and carry out two point correction, substitute into following formula, image Y after calculation correction,

Wherein, X is the image of precorrection, and Y is the image after correcting, and Δ O is shutter corrected parameter, B _jbe jth width background image, K is gain calibration parameter.

Further, described computing unit comprises:

First computation subunit, for starting soon behind the door, according to the shutter image of acquisition and the Average value compare of background image, calculates the gain calibration parameter that shutter image is corresponding;

Second computation subunit, for according to after shutter image two point correction, and the side-play amount after correcting in conjunction with gain calibration parameter acquiring, thus calculate shutter corrected parameter.

Further, described correcting unit comprises:

Obtain subelement, for the target image place temperature range according to precorrection, calculate the average of target image, thus get gain calibration parameter;

Syndrome unit, for according to getting gain calibration parameter, carrying out two point correction to target image, substituting into corresponding formula, calculates image Y after correcting.

The invention has the beneficial effects as follows: by introducing parameters revision, make two point correction become Supplements, nonlinearity can be reduced on the impact correcting result, thus being corrected result more accurately; The present invention realizes simply, operand is minimum, market prospects are wide; Meanwhile, there is good scene adaptive, thus ensure that the validity of calibration result.

Accompanying drawing explanation

Fig. 1 is the flow chart of the multi-point correcting method of a kind of infrared focus plane provided by the invention;

Fig. 2 is the structural representation of the Supplements system of a kind of infrared focus plane provided by the invention.

In accompanying drawing, the list of parts representated by each label is as follows:

21, collecting unit, 22, computing unit, the 221, first computing unit, the 222, second computing unit, 23, correcting unit, 231, obtain subelement, 232, syndrome unit.

Embodiment

In order to make object of the present invention, technical scheme and advantage clearly understand, below in conjunction with drawings and Examples, the present invention is further elaborated.Should be appreciated that specific embodiment described herein only in order to explain the present invention, be not intended to limit the present invention.

Fig. 1 is the flow chart of the multi-point correcting method of a kind of infrared focus plane provided by the invention, and details are as follows:

Step 1, infrared focal plane detector, in operating temperature range, gathers the image image as a setting of different temperatures black matrix every 5 DEG C;

In this example, infrared focus plane arranges light-sensing element array, the infrared ray launched from wireless distant place through optical system imaging on these photo-sensitive cells of system focal plane, detector will receive light signal and is converted to the signal of telecommunication and carries out amplifying, sampling maintenance, by exporting buffering and multiplex system, finally sending to surveillance and forming image.

Preferably, in described step 1, the scope of operational temperature conditions is-20 DEG C ~ 80 DEG C.Can choose the mode of refrigeration mode or non-refrigeration type according to the temperature conditions of work, refrigeration mode mode is higher than the mode accuracy of non-refrigeration type; Also can choose Infrared Detectors according to condition of work is photon detector or thermal detector.

The temperature of described black matrix covers the temperature range of detector Observable scene, temperature interval every 5 DEG C from low to high, background image is corresponding B respectively ₁, B ₂, B ₃b _n, the average of background image is respectively $\stackrel{\&OverBar;}{B_1},\stackrel{\&OverBar;}{B_2},$ $\stackrel{\&OverBar;}{B_3}\&CenterDot;\&CenterDot;\&CenterDot;\&CenterDot;\&CenterDot;\&CenterDot;\stackrel{\&OverBar;}{B_n},$ And $\stackrel{\&OverBar;}{B_1}<\stackrel{\&OverBar;}{B_2}<\stackrel{\&OverBar;}{B_3}<\&CenterDot;\&CenterDot;\&CenterDot;\&CenterDot;\&CenterDot;\&CenterDot;<\stackrel{\&OverBar;}{B_n}.$

Step 2, starts shutter, obtains shutter image relevant parameter, and is inserted in following formula acquisition shutter corrected parameter according to background image,

$\mathrm{\&Delta;O}=(X_s-B_i)-({\stackrel{\&OverBar;}{X}}_s-{\stackrel{\&OverBar;}{B}}_i)\&times;\frac{\stackrel{\&OverBar;}{K_s}}{K_s}$

Wherein, Δ O is shutter corrected parameter, B _ithe i-th width background image, be the average of background image, shutter image relevant parameter comprises: X _s, k _swith wherein X _sshutter image, the average of shutter image, K _sthe gain calibration parameter that shutter image is corresponding, k _saverage;

Preferably, the gain calibration parameter K that in described step 2, shutter image is corresponding _s, be specially:

When shutter timing determines place temperature range, obtain the image X of shutter _s, and calculate the average of shutter image relatively with the average of background image, determine be positioned at interval the bias correction parameter that then shutter image is corresponding is the gain calibration parameter that shutter image is corresponding is $K_s=({\stackrel{\&OverBar;}{B}}_{i+1}-{\stackrel{\&OverBar;}{B}}_i)/(B_{i+1}-B_i).$

Preferably, described step 2 specifically also comprises:

To shutter image X _scarry out two point correction, obtain shutter image X _simage Δ Y after two point correction _s, then Y _s=(X _s-B _i) × K _s; Wherein, B _ithe i-th width background image, and according to image Δ Y after two point correction _sobtain the offset Δ Y after correcting _s, wherein, y _saverage; Substitute into following formula, calculate shutter corrected parameter Δ O,

$\mathrm{\&Delta;O}=\frac{\mathrm{\&Delta;}{Y}_S}{K_s}$ Be transformed to $\mathrm{\&Delta;O}=(X_s-B_i)-({\stackrel{\&OverBar;}{X}}_s-{\stackrel{\&OverBar;}{B}}_i)\&times;\frac{\stackrel{\&OverBar;}{K_s}}{K_s}$

In formula, Δ O is shutter corrected parameter, Δ Y _sfor the image after two point correction, K _sfor the gain calibration parameter that shutter image is corresponding, k _saverage, X _sfor shutter image, for the average of shutter image, B _ithe i-th width background image, it is the average of background image.

Step 3: according to shutter corrected parameter Δ O, introduces target image corresponding gain calibration parameter K and bias correction parameter B _jput school and carry out two point correction, substitute into following formula, image Y after calculation correction,

Y＝[X-(B _j+ΔO)]×K

Wherein, X is the image of precorrection, and Y is the image after correcting, and Δ O is shutter corrected parameter, B _jbe jth width background image, K is gain calibration parameter.

Preferably, described step 3 specifically comprises as follows:

According to the target image place temperature range of precorrection, calculate the average of target image relatively with the average of background image, determine be positioned at interval bias correction parameter then corresponding to target image is B _j, gain calibration parameter is then, two point correction is carried out to target image, substitutes into following formula, image Y after calculation correction:

Wherein, X is the image of precorrection, and Y is the image after correcting, and Δ O is shutter corrected parameter, B _jbe jth width background image, K is gain calibration parameter.

As shown in Figure 2, be a kind of structural representation of Supplements system of infrared focus plane, comprise:

Collecting unit 21, in operating temperature range, gathers the image image as a setting of different temperatures black matrix every 5 DEG C;

Computing unit 22, for starting shutter, obtains shutter image relevant parameter, and is inserted in following formula acquisition shutter corrected parameter according to background image,

$\mathrm{\&Delta;O}=(X_s-B_i)-({\stackrel{\&OverBar;}{X}}_s-{\stackrel{\&OverBar;}{B}}_i)\&times;\frac{\stackrel{\&OverBar;}{K_s}}{K_s}$

Wherein, Δ O is shutter corrected parameter, B _ithe i-th width background image, be the average of background image, shutter image relevant parameter comprises shutter image X _swith the average of shutter image k _sthe gain calibration parameter that shutter image is corresponding, k _saverage;

Correcting unit 23, for according to shutter corrected parameter Δ O, introduces target image corresponding gain calibration parameter K and bias correction parameter B _jput school and carry out two point correction, substitute into following formula, image Y after calculation correction,

Wherein, X is the image of precorrection, and Y is the image after correcting, and Δ O is shutter corrected parameter, B _jbe jth width background image, K is gain calibration parameter.

Preferably, described computing unit 22 comprises:

First computation subunit 221, for starting soon behind the door, according to the shutter image of acquisition and the Average value compare of background image, calculates the gain calibration parameter that shutter image is corresponding;

Second computation subunit 222, for according to after shutter image two point correction, and the side-play amount after correcting in conjunction with gain calibration parameter acquiring, thus calculate shutter corrected parameter.

Preferably, described correcting unit 231 comprises:

Obtain subelement 231, for the target image place temperature range according to precorrection, calculate the average of target image, thus get gain calibration parameter;

Syndrome unit 232, for according to getting gain calibration parameter, carrying out two point correction to target image, substituting into corresponding formula, calculates image Y after correcting.

In embodiments of the present invention, by introducing parameters revision, making two point correction become Supplements, nonlinearity can be reduced on the impact correcting result, thus being corrected result more accurately; The present invention realizes simply, operand is minimum, market prospects are wide; Meanwhile, there is good scene adaptive, thus ensure that the validity of calibration result.

The above; be only the specific embodiment of the present invention, but protection scope of the present invention is not limited thereto, is anyly familiar with those skilled in the art in the technical scope that the present invention discloses; the change that can expect easily or replacement, all should be encompassed within protection scope of the present invention.Therefore, protection scope of the present invention should be as the criterion with the protection range of claim.

Claims (9)

1. a multi-point correcting method for infrared focus plane, is characterized in that, comprises the steps:

Step 1, infrared focal plane detector, in operating temperature range, gathers the image image as a setting of different temperatures black matrix every 5 DEG C;

Step 2, starts shutter, obtains shutter image relevant parameter, and is inserted in following formula acquisition shutter corrected parameter according to background image:

$\mathrm{\&Delta;O}=(X_s-B_i)({\stackrel{\&OverBar;}{X}}_s-{\stackrel{\&OverBar;}{B}}_i)\&times;\frac{\stackrel{\&OverBar;}{K_s}}{K_s}$

Wherein, Δ O is shutter corrected parameter, B _ithe i-th width background image, be the average of background image, shutter image relevant parameter comprises shutter image X _swith the average of shutter image k _sthe gain calibration parameter that shutter image is corresponding, k _saverage;

Step 3, according to shutter corrected parameter Δ O, introduces target image corresponding gain calibration parameter K and bias correction parameter B _jput school and carry out two point correction, substitute into following formula, image Y after calculation correction,

Wherein, X is the image of precorrection, and Y is the image after correcting, and Δ O is shutter corrected parameter, B _jbe jth width background image, K is gain calibration parameter.

2. the multi-point correcting method of a kind of infrared focus plane according to claim 1, is characterized in that, in described step 1, the scope of working temperature is-20 DEG C ~ 80 DEG C.

3. the multi-point correcting method of a kind of infrared focus plane according to claim 1, is characterized in that, details are as follows for described step 1:

The temperature of described black matrix covers the temperature range of detector observation scene, temperature interval every 5 DEG C from low to high, background image is corresponding B respectively ₁, B ₂, B ₃... B _n, the average of background image is respectively and $\stackrel{\&OverBar;}{B_1}<\stackrel{\&OverBar;}{B_2}<\stackrel{\&OverBar;}{B_3}\&CenterDot;\&CenterDot;\&CenterDot;\&CenterDot;\&CenterDot;\&CenterDot;<\stackrel{\&OverBar;}{B_n}.$

4. the multi-point correcting method of a kind of infrared focus plane according to claim 1, is characterized in that, the gain calibration parameter K that in described step 2, shutter image is corresponding _s, be specially:

When shutter timing determines place temperature range, obtain the image X of shutter _s, and calculate the average of shutter image relatively with the average of background image, determine be positioned at interval the bias correction parameter that then shutter image is corresponding is the gain calibration parameter that shutter image is corresponding is $K_s=({\stackrel{\&OverBar;}{B}}_{i+1}-{\stackrel{\&OverBar;}{B}}_i)/(B_{i+1}-B_i).$

5. the multi-point correcting method of a kind of infrared focus plane according to claim 4, is characterized in that, described step 2 specifically also comprises:

To shutter image X _scarry out two point correction, obtain shutter image X _simage Δ Y after two point correction _s, then Y _s=(X _s-B _i) × K _s; Wherein, B _ithe i-th width background image, and according to image Δ Y after two point correction _sobtain the offset Δ Y after correcting _s, wherein, y _saverage; Substitute into following formula, calculate shutter corrected parameter Δ O:

$\mathrm{\&Delta;O}=\frac{{\mathrm{\&Delta;Y}}_S}{K_s}$ Be transformed to $\mathrm{\&Delta;O}=(X_s-B_i)({\stackrel{\&OverBar;}{X}}_s-{\stackrel{\&OverBar;}{B}}_i)\&times;\frac{\stackrel{\&OverBar;}{K_s}}{K_s}$

In formula, Δ O is shutter corrected parameter, Δ Y _sfor the image after two point correction, K _sfor the gain calibration parameter that shutter image is corresponding, k _saverage, X _sfor shutter image, for the average of shutter image, B _ithe i-th width background image, it is the average of background image.

6. the multi-point correcting method of a kind of infrared focus plane according to claim 1, is characterized in that, described step 3 specifically comprises as follows:

According to the target image place temperature range of precorrection, calculate the average of target image relatively with the average of background image, determine be positioned at interval bias correction parameter then corresponding to target image is B _j, gain calibration parameter is then, two point correction is carried out to target image, substitutes into following formula, image Y after calculation correction:

Wherein, X is the image of precorrection, and Y is the image after correcting, and Δ O is shutter corrected parameter, B _jbe jth width background image, K is gain calibration parameter.

7. a Supplements system for infrared focus plane, is characterized in that, comprising:

Collecting unit, in operating temperature range, gathers the image image as a setting of different temperatures black matrix every 5 DEG C;

Computing unit, for starting shutter, obtains shutter image relevant parameter, and is inserted in following formula acquisition shutter corrected parameter according to background image,

$\mathrm{\&Delta;O}=(X_s-B_i)({\stackrel{\&OverBar;}{X}}_s-{\stackrel{\&OverBar;}{B}}_i)\&times;\frac{\stackrel{\&OverBar;}{K_s}}{K_s}$

Wherein, Δ O is shutter corrected parameter, B _ithe i-th width background image, be the average of background image, shutter image relevant parameter comprises shutter image X _swith the average of shutter image k _sthe gain calibration parameter that shutter image is corresponding, k _saverage;

Correcting unit, for according to shutter corrected parameter Δ O, introduces target image corresponding gain calibration parameter K and bias correction parameter B _jput school and carry out two point correction, substitute into following formula, image Y after calculation correction,

Wherein, X is the image of precorrection, and Y is the image after correcting, and Δ O is shutter corrected parameter, B _jbe jth width background image, K is gain calibration parameter.

8. the Supplements system of a kind of infrared focus plane according to claim 7, is characterized in that, described computing unit comprises:

First computation subunit, for starting soon behind the door, according to the shutter image of acquisition and the Average value compare of background image, calculates the gain calibration parameter that shutter image is corresponding;

Second computation subunit, for according to after shutter image two point correction, and the side-play amount after correcting in conjunction with gain calibration parameter acquiring, thus calculate shutter corrected parameter.

9. the Supplements system of a kind of infrared focus plane according to claim 7, is characterized in that, described correcting unit comprises:

Obtain subelement, for the target image place temperature range according to precorrection, calculate the average of target image, thus get gain calibration parameter;

Syndrome unit, for according to getting gain calibration parameter, carrying out two point correction to target image, substituting into corresponding formula, calculates image Y after correcting.