CN104236859A - Satellite-borne area array CCD camera point spread function measuring device and method - Google Patents
Satellite-borne area array CCD camera point spread function measuring device and method Download PDFInfo
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Abstract
The invention relates to a satellite-borne area array CCD camera point spread function measuring device and method. The device comprises a light source system, a target, a collimating device, an area array CCD camera and an image collecting system; the target is placed on a focus face of the collimating device, the collimating device and the optical axis of the area array CCD camera are coaxially arranged, the target is illuminated by uniform light generated by the light source system to form an image on the focusing face of the CCD camera through the collimating device and the area array CCD camera, the image of the target is formed, and the image collecting system collects and processes imaging results. According to the satellite-borne area array CCD camera point spread function measuring device and method, phase position alignment is considered in target design, an experimental method and data processing, the PSF measurement accuracy can be guaranteed, and the blank in the satellite-borne area array CCD camera PSF testing method is filled.
Description
Technical field
The present invention relates to measurement mechanism and the method for point spread function, a kind of particularly measurement mechanism of spaceborne area array CCD camera point spread function and method, be applicable to the point spread function test of face battle array gazing type CCD camera or CMOS camera, belong to aerospace optical remote sensing technical field.
Background technology
Optical system in the ideal situation, the luminous energy that object space a bit sends also concentrates on a bit in image space, but during the optical system imaging of reality, due to the impact of diffraction and aberration and other factors, the light that object space a bit sends is be distributed in certain region in image space, and its distribution curve is called point spread function PSF.Modulation transfer function is the important indicator of objective evaluation optical system imaging quality, domestic in order to quantitative evaluation camera imaging quality at present, all carry out the MTF test in laboratory before transmitting, but MTF is the amplitude information of PSF at frequency domain, does not comprise phase information.MTF method of testing conventional at present comprises following three kinds, the first is contrast rectangle Bar Method, may be used for face battle array or push away sweeping camera MTF and testing, two kinds of method of testings are provided in " space flight optical remote sensor MTF Testing Technology Study " literary composition that the people such as Huang Qiaolin deliver for 2006 on " space flight returns and remote sensing ", one is high-contrast rectangular target mapping method for testing, the method is by the impact of sampling phase, test error is larger, another kind of Low Frequency Bar Method is to phase-unsensitive, but easily affected by noise; The second is oblique sword limit Bar Method, be applicable to the MTF ground test of area array CCD, " the MTF measuring technology of area array CCD camera " literary composition that the people such as Zhang Xiaohong deliver for 2006 in the 19 academic conference of space exploration Professional Committee of China's Space science association describes experimental technique and data processing algorithm, this disposal route adds sampled point, but accurately cannot locate initial phase; The third is point source or slit method of testing, be applicable to the MTF test of area array CCD, point source method experimental system is described in detail in the flat master thesis of Wu Hai " point source method MTF Testing Technology Study ", experimental technique is to point-sourcre imaging, the method computational accuracy is higher, but the alignment precision of collimation microcobjective requires higher, must the imaging in a pixel of guarantee point light source.
Summary of the invention
The technical matters that the present invention solves is: the present situation only surveying MTF for domestic existing spaceborne area array CCD camera ground, a kind of laboratory measurement device and method of spaceborne area array CCD camera point spread function is proposed, the present invention solves phase alignment problem by drone design and data processing method, ensure the test accuracy of area array CCD camera PSF, meet the demand that area array CCD camera PSF tests to the full extent.
Technical scheme of the present invention is:
A measurement mechanism for spaceborne area array CCD camera point spread function, is characterized in that: comprise light-source system, target, parallel light tube, area array CCD camera and image capturing system;
Target is placed on the focal plane of parallel light tube, the coaxial placement of optical axis of parallel light tube and area array CCD camera;
Light-source system is radiated on target after producing even light, then through parallel light tube and area array CCD camera, is imaged on the focal plane of area array CCD camera, and form the image of target, image capturing system carries out acquisition and processing to the imaging results of area array CCD camera;
Target comprises 100 asterisms, the first calibration line and the second calibration line, and described 100 asterisms are respectively the first asterism to the 100 asterism;
First asterism is all identical to the 100 asterism shape and size, and is square light hole, and the length of side of square light hole is 0.9 times of standard length L; Described L=(f
col/ f
cam) d, wherein f
colfor the focal length of parallel light tube, f
camfor the focal length of area array CCD camera, d is detector cells spacing in area array CCD camera; First calibration line and the second calibration line are rectangle light hole, and the width of rectangle light hole is 0.9 times of standard length L, and length is greater than 5 times of standard length L;
First asterism is respectively to coordinate in target plane right-angle coordinate XOY of the 100 asterism, the first calibration line and the second calibration line:
The apex coordinate in the first calibration line rectangle structure upper left corner is (-20L, 80L); The apex coordinate in the second calibration line rectangle structure upper left corner is (80L, 200L); The coordinate of the first asterism is (0,0); The coordinate of the i-th asterism is (a19.9L, b19.9L), wherein a be i divided by 10 complementing part to subtract 1, b be i divided by 10 integral part, 1<i<100; The coordinate of the 100 asterism is (179.1L, 179.1L) point; Described asterism coordinate is the coordinate in the asterism square structure upper left corner;
The true origin O of described target plane right-angle coordinate XOY is the summit that the first asterism square structure is positioned at the upper left corner, and the positive dirction of X-axis is that the first asterism points to the second asterism, and the positive dirction of Y-axis is that the first asterism points to the 11 asterism;
Described target size length and width are all greater than 300L.
The first asterism in described target is to the 100 asterism, the first calibration line and the second calibration line printing opacity, and remainder is light tight, and light transmission part and lightproof part contrast are not less than 100:1.
Utilize a measuring method for the area array CCD camera point spread function of measurement mechanism described in claim 1, step is as follows:
(1) image capturing system constantly adjusts the position of target while gathering target image, until the first calibration line of target is positioned on the same row of image array, the second calibration line is positioned at image array with in a line simultaneously, the position of fixing now target;
(2) time shutter of installation surface array CCD camera, the first asterism is made to the scope of the 100 asterism gray-scale value to be in the picture: [0.5K, 0.6K]; Utilize image capturing system to collect the image of the target under P frame current exposure time, described K is saturated gray-scale value, P be greater than 100 positive integer;
(3) neighbor pixel of pointwise to the asterism i on X frame target image is sampled, and is specially:
Make the coordinate of this asterism i in image array for (x, y), then sample to its neighbor pixel (x+n, y) and (x, y+n), described n is integer, and-N≤n≤N; Described i is positive integer, and 1<=i<=100; Described N is positive integer, and N >=10;
The sequence length obtained of sampling is 2N+1, and wherein, the sampled point gray value sequence identical with the y coordinate of asterism i is x
i-N, x
i-N+1, x
i-N+2..., x
i, x
i+1, x
i+2..., x
i+N-1, x
i+N, the sampled point gray value sequence identical with the x coordinate of asterism i is y
i-N, y
i-N+1, y
i-N+2..., y
i, y
i+1, y
i+2..., y
i+N-1, y
i+N; If identical about the gray-scale value of the point-symmetric sampled point of asterism i, i.e. x
i-1=x
i+1, x
i-2=x
i+2, x
i-3=x
i+3, x
i-N=x
i+N, and y
i-1=y
i+1, y
i-2=y
i+2, y
i-3=y
i+3, y
i-N=y
i+N, then choosing this point sequence is impact point sequence, enters step (4); Otherwise return step (3) to process next frame image;
(4) according to the full trap electron number M of area array CCD camera and image quantization figure place bs, the impact point sequence obtained in step (3) is converted to electron number sequence, described e-book sequence is
described transfer process is specifically by formula:
Provide, wherein x is the gray-scale value of sampled point, x
efor electron number;
(5) the electron number sequence obtained in step (4) is normalized, after obtaining normalization electron number sequence, utilizes Gaussian function N (μ
1, μ
2, σ
1, σ
2) carry out matching, obtain X two field picture Gaussian distribution point spread function variances sigma
1and σ
2;
Described normalization electron number sequence is by formula:
Provide, in formula, x ' is normalized electron number sequence,
(6) method of each two field picture in P two field picture under current exposure time according to step (4) ~ step (5) is processed, obtain the Gaussian distribution point spread function variance of each two field picture, finally obtain Gaussian distribution point spread function variance sequence σ
p1and σ
p2, to σ
p1and σ
p2make histogram distribution statistics, obtain histogram sequence, and this histogram sequence matching is obtained gauss of distribution function N (μ
h1, μ
h2, σ
h1, σ
h2), N (0,0, σ
h1, σ
h2) be the point spread function of area array CCD camera;
(7) utilize the point spread function of the area array CCD camera obtained in step (6) to carry out image restoration to the imaging data of area array CCD camera, improve Remote Sensing Image Quality.
The present invention's advantage is compared with prior art:
(1) instant invention overcomes the defect that MTF is only surveyed on spaceborne area array CCD camera ground, carry out PSF ground test, Fourier transform is done to PSF can obtain MTF simultaneously, test PSF directly can describe the imaging performance of camera, also plays vital effect to process such as later image recoveries simultaneously;
(2) the present invention is by the design of the calibration line position in target and shape, the first calibration line of target is made to be positioned on the same row of image array, second calibration line is positioned at image array with in a line simultaneously, ensure that target plane is parallel with area array CCD detector, thus ensure that measuring accuracy;
(3) the present invention passes through the design of asterism position and shape, makes to have at least an asterism to drop on completely in a CCD pixel in target, thus finds the impact point sequence for calculating PSF function, add the accuracy of proving installation and method;
(4) the present invention judges the phase condition of asterism in data processing by symmetry, has carried out adjustment processing, has reduced noise effect, reduce measuring error by statistical method to repetitive measurement result;
(5) the present invention can utilize existing MTF test macro equipment completely, is easy to Project Realization.
Accompanying drawing explanation
Fig. 1 is that PSF of the present invention tests drone design figure;
Fig. 2 is PSF experimental provision schematic diagram of the present invention;
Fig. 3 is method of testing process flow diagram of the present invention;
Fig. 4 is flow chart of data processing figure of the present invention.
Embodiment
Below in conjunction with accompanying drawing, the specific embodiment of the present invention is set forth in detail.
The experimental provision that the present invention relates to as shown in Figure 2, comprising: light-source system 103, target 104, parallel light tube 105, area array CCD camera 106 and image capturing system 107.
Target 104 is placed on the focal plane of parallel light tube 105, the coaxial placement of optical axis of parallel light tube 105 and area array CCD camera 106, the uniform illumination that target 104 is produced by light-source system 103 is bright, through parallel light tube 105 and area array CCD camera 106, be imaged on the focal plane of area array CCD camera 106, form the image of target 104, image capturing system 107 pairs of imaging results carry out acquisition and processing.
Be illustrated in figure 1 PSF experimental provision schematic diagram of the present invention, as shown in Figure 1, target 104 comprise the first asterism 1 to the 100 asterism 100, first calibration line 101 and the second calibration line 102.
All asterisms and calibration line printing opacity on target 104, remainder is light tight, and printing opacity and lightproof part contrast are not less than 100:1.
Rectangular coordinate system x-y set up by target 104, and x-axis is the upper edge of the first asterism 1, and y-axis is the left margin of the first asterism 1, and the positive dirction of x-axis is that the first asterism 1 points to the second asterism 2, and the positive dirction of y-axis is that the first asterism points to the 11 asterism 11.
Definition standard length L, L=(f
col/ f
cam) d, wherein f
colfor the focal length of parallel light tube 105, f
camfor the focal length of area array CCD camera 106, d is detector cells spacing in area array CCD camera 106; L represents the corresponding physical length in target 104 position of detector cells spacing.
First asterism 1 to the 100 asterism 100 is square, and the length of side is 0.9 times of standard length L; First calibration line 101 and the second calibration line 102 are rectangle, and width is 0.9 times of standard length L, and length is greater than 5 times of standard length L.
Target 104 is followed successively by along the position of x-axis calibration line and asterism: the first calibration line 101 is positioned at (-20L, 80L) point on coordinate system; Second calibration line 102 is positioned at (80L, 200L) point on coordinate system; (0,0) point on first asterism 1 coordinate system; (19.9L, 0) point on second asterism 2 coordinate system; (39.8L, 0) point on 3rd asterism 3 coordinate system; (59.7L, 0) point on 4th asterism 4 coordinate system; (79.6L, 0) point on Alcor point 5 coordinate system; (99.5L, 0) point on 6th asterism 6 coordinate system; (119.4L, 0) point on seven-star point 7 coordinate system; (139.3L, 0) point on 8th asterism 8 coordinate system; (159.2L, 0) point on 9th asterism 9 coordinate system; (179.1L, 0) point on tenth asterism 10 coordinate system; (0,19.9L) point on 11 asterism 11 coordinate system; (19.9L, 19.9L) point on 12 asterism 12 coordinate system; (39.8L, 19.9L) point on 13 asterism 13 coordinate system; (59.7L, 19.9L) point on 14 asterism 14 coordinate system; (79.6L, 19.9L) point on tenth five-pointed star point 15 coordinate system; (99.5L, 19.9L) point on 16 asterism 16 coordinate system; (119.4L, 19.9L) point on tenth seven-star point 17 coordinate system; (139.3L, 19.9L) point on 18 asterism 18 coordinate system; (159.2L, 19.9L) point on 19 asterism 19 coordinate system; (179.1L, 19.9L) point on 20 asterism 20 coordinate system; (0,39.8L) point on 21 asterism 21 coordinate system; (19.9L, 39.8L) point on 22 asterism 22 coordinate system; (39.8L, 39.8L) point on 23 asterism 23 coordinate system; (59.7L, 39.8L) point on 24 asterism 24 coordinate system; (79.6L, 39.8L) point on 20 five-pointed star point 25 coordinate system; (99.5L, 39.8L) point on 26 asterism 26 coordinate system; (119.4L, 39.8L) point on 20 seven-star point 27 coordinate system; (139.3L, 39.8L) point on 28 asterism 28 coordinate system; (159.2L, 39.8L) point on 29 asterism 29 coordinate system; (179.1L, 39.8L) point on 30 asterism 30 coordinate system; (0,60.7L) point on 31 asterism 31 coordinate system; (19.9L, 59.7L) point on 32 asterism 32 coordinate system; (39.8L, 59.7L) point on 33 asterism 33 coordinate system; (59.7L, 59.7L) point on 34 asterism 34 coordinate system; (79.6L, 59.7L) point on 30 five-pointed star point 35 coordinate system; (99.5L, 59.7L) point on 36 asterism 36 coordinate system; (119.4L, 59.7L) point on 30 seven-star point 37 coordinate system; (139.3L, 59.7L) point on 38 asterism 38 coordinate system; (159.2L, 59.7L) point on 39 asterism 39 coordinate system; (179.1L, 59.7L) point on 40 asterism 40 coordinate system; (0,79.6L) point on 41 asterism 41 coordinate system; (19.9L, 79.6L) point on 42 asterism 42 coordinate system; (39.8L, 79.6L) point on 43 asterism 43 coordinate system; (59.7L, 79.6L) point on 44 asterism 44 coordinate system; (79.6L, 79.6L) point on 40 five-pointed star point 45 coordinate system; (99.5L, 79.6L) point on 46 asterism 46 coordinate system; (119.4L, 79.6L) point on 40 seven-star point 47 coordinate system; (139.3L, 79.6L) point on 48 asterism 48 coordinate system; (159.2L, 79.6L) point on 49 asterism 49 coordinate system; (179.1L, 79.6L) point on 50 asterism 50 coordinate system; (0,99.5L) point on 51 asterism 51 coordinate system; (19.9L, 99.5L) point on 52 asterism 52 coordinate system; (39.8L, 99.5L) point on 53 asterism 53 coordinate system; (59.7L, 99.5L) point on 54 asterism 54 coordinate system; (79.6L, 99.5L) point on 50 five-pointed star point 55 coordinate system; (99.5L, 99.5L) point on 56 asterism 56 coordinate system; (119.4L, 99.5L) point on 50 seven-star point 57 coordinate system; (139.3L, 99.5L) point on 58 asterism 58 coordinate system; (159.2L, 99.5L) point on 59 asterism 59 coordinate system; (179.1L, 99.5L) point on 60 asterism 60 coordinate system; (0,119.4L) point on 61 asterism 61 coordinate system; (19.9L, 119.4L) point on 62 asterism 62 coordinate system; (39.8L, 119.4L) point on 63 asterism 63 coordinate system; (59.7L, 119.4L) point on 64 asterism 64 coordinate system; (79.6L, 119.4L) point on 60 five-pointed star point 65 coordinate system; (99.5L, 119.4L) point on 66 asterism 66 coordinate system; (119.4L, 119.4L) point on 60 seven-star point 67 coordinate system; (139.3L, 119.4L) point on 68 asterism 68 coordinate system; (159.2L, 119.4L) point on 69 asterism 69 coordinate system; (179.1L, 119.4L) point on 70 asterism 70 coordinate system; (0,139.3L) point on 71 asterism 71 coordinate system; (19.9L, 139.3L) point on 72 asterism 72 coordinate system; (39.8L, 139.3L) point on 73 asterism 73 coordinate system; (59.7L, 140.3L) point on 74 asterism 74 coordinate system; (79.6L, 139.3L) point on 70 five-pointed star point 75 coordinate system; (99.5L, 139.3L) point on 76 asterism 76 coordinate system; (119.4L, 139.3L) point on 70 seven-star point 77 coordinate system; (139.3L, 139.3L) point on 78 asterism 78 coordinate system; (159.2L, 139.3L) point on 79 asterism 79 coordinate system; (179.1L, 139.3L) point on 80 asterism 80 coordinate system; (0,159.2L) point on 81 asterism 81 coordinate system; (19.9L, 159.2L) point on 82 asterism 82 coordinate system; (39.8L, 159.2L) point on 83 asterism 83 coordinate system; (59.7L, 159.2L) point on 84 asterism 84 coordinate system; (79.6L, 159.2L) point on 80 five-pointed star point 85 coordinate system; (99.5L, 159.2L) point on 86 asterism 86 coordinate system; (119.4L, 159.2L) point on 80 seven-star point 87 coordinate system; (139.3L, 159.2L) point on 88 asterism 88 coordinate system; (159.2L, 159.2L) point on 89 asterism 89 coordinate system; (179.1L, 159.2L) point on 90 asterism 90 coordinate system; (0,179.1L) point on 91 asterism 91 coordinate system; (19.9L, 179.1L) point on 92 asterism 92 coordinate system; (39.8L, 179.1L) point on 93 asterism 93 coordinate system; (59.7L, 179.1L) point on 94 asterism 94 coordinate system; (79.6L, 179.1L) point on 90 five-pointed star point 95 coordinate system; (99.5L, 179.1L) point on 96 asterism 96 coordinate system; (119.4L, 179.1L) point on 90 seven-star point 97 coordinate system; (139.3L, 179.1L) point on 98 asterism 98 coordinate system; (159.2L, 179.1L) point on 99 asterism 99 coordinate system; (179.1L, 179.1L) point on 100 asterism 100 coordinate system;
A kind of measuring method utilizing the area array CCD camera point spread function of above-mentioned measurement mechanism of the present invention, be divided into measuring process and process frame by frame target image, step is specific as follows:
One, measuring process:
(1) target 104 to be arranged on the focal plane of parallel light tube 105 (calibration line 101 and calibration line 102 all perpendicular to the optical axis of parallel light tube, and target 104 is parallel to detector plane), to adjust the position of target illuminator 103;
(2) be placed in by area array CCD camera 106 before parallel light tube 105 exports, adjusted the position of camera by camera adjusting device, ensure that camera light inlet is aimed at the light-emitting window of parallel light tube 105, the effective aperture of parallel light tube 105 is full of camera entrance pupil;
(3) connect the cable between area array CCD camera 106 and image capturing system 107, and energising checks, guarantees working properly;
(4) light-source system 103 is opened;
(5) image that image capturing system 107 gathers target 104 is observed, according to calibration line wide variety moving target mark 104 on x direction and y direction, until calibration line 101 appears on the same row of image array, calibration line 102 appears in same a line of image array simultaneously, and the position of fixing target 104;
(6) time shutter of installation surface array CCD camera 106, the first asterism 1 is made to the scope of the 100 asterism 100 gray-scale value to be in the picture: [0.5K, 0.6K]; Utilize image capturing system 107 to collect the image of the target 104 under P frame current exposure time, described K is saturated gray-scale value, P be greater than 100 positive integer;
(7) camera focal plane is adjusted to optimal focal plane position;
(8) repeated test storage figure picture, image acquisition frame number is greater than 100;
Two, treatment step is frame by frame carried out to the image of target 104:
(1) neighbor pixel of pointwise to the asterism i on X frame target 104 image is sampled, and is specially:
Make the coordinate of this asterism i in image array for (x, y), then sample to its neighbor pixel (x+n, y) and (x, y+n), described n is integer, and-N≤n≤N; Described i is integer, and 1<=i<=100; Described N is positive integer, and N >=10;
The sequence length obtained of sampling is 2N+1, and wherein, the sampled point gray value sequence identical with the y coordinate of asterism i is x
i-N, x
i-N+1, x
i-N+2..., x
i, x
i+1, x
i+2..., x
i+N-1, x
i+N, the sampled point gray value sequence identical with the x coordinate of asterism i is y
i-N, y
i-N+1, y
i-N+2..., y
i, y
i+1, y
i+2..., y
i+N-1, y
i+N; If identical about the gray-scale value of the point-symmetric sampled point of asterism i, i.e. x
i-1=x
i+1, x
i-2=x
i+2, x
i-3=x
i+3, x
i-N=x
i+N, and y
i-1=y
i+1, y
i-2=y
i+2, y
i-3=y
i+3, y
i-N=y
i+N, then choosing this point sequence is impact point sequence, enters step (2); Otherwise return step (1) to process next frame image;
(2) according to the full trap electron number M of area array CCD camera 106 and image quantization figure place bs, the impact point sequence obtained in step (1) is converted to electron number sequence, described e-book sequence is
described transfer process is specifically by formula:
Provide, wherein x is the gray-scale value of sampled point, x
efor electron number;
(3) the electron number sequence obtained in step (2) is normalized, after obtaining normalization electron number sequence, utilizes Gaussian function N (μ
1, μ
2, σ
1, σ
2) carry out matching, obtain X two field picture Gaussian distribution point spread function variances sigma
1and σ
2;
Described normalization electron number sequence is by formula:
Provide, in formula, x ' is normalized electron number sequence,
(4) method of each two field picture in P two field picture under the prior exposure time according to step (2) ~ step (3) is processed, obtain the Gaussian distribution point spread function variance of each two field picture, finally obtain Gaussian distribution point spread function variance sequence σ
p1and σ
p2, to σ
p1and σ
p2make histogram distribution statistics, obtain histogram sequence, and this histogram sequence matching is obtained gauss of distribution function N (μ
h1, μ
h2, σ
h1, σ
h2), N (0,0, σ
h1, σ
h2) be the point spread function of area array CCD camera 106;
(5) point spread function of the area array CCD camera 106 obtained in step (4) is utilized to carry out image restoration to the imaging data of area array CCD camera 106.
The area array CCD camera of China's model remote sensing satellite have employed the area array CCD camera point spread function measurement mechanism of the present invention's design first and method has carried out testing the point spread function obtaining this camera, and carry out the modulation transfer function that two-dimensional Fourier transform obtains camera, use measurement mechanism same except target directly to carry out the test of the modulation transfer function of this camera simultaneously, the method designed with the present invention is tested the modulation transfer function result obtained and is contrasted, and error is within 5%; The point spread function using ground test to obtain carries out restoration disposal to ground image, the sharpness of image, MTF have and promote by a relatively large margin, before and after process, parameter comparison is in table 1, and table 1 is use the present invention to test the parameter comparison that the point spread function obtained carries out image restoration.
Table 1
| Parameter | Relative value |
| Gray level co-occurrence matrixes angle second moment | Reduce by 50% |
| Gray level co-occurrence matrixes entropy | Increase by 30% |
| MTF | Improve 50% |
The present invention devises new target and target image data processing method, achieve the test of area array CCD camera PSF function, camera properties can be described intuitively, can be applicable to the point spread function test of spaceborne and airborne visible ray/multispectral battle array gazing type CCD camera or CMOS camera.
The content be not described in detail in instructions of the present invention belongs to ability in the known technology of technician.
Claims (3)
1. a measurement mechanism for spaceborne area array CCD camera point spread function, is characterized in that: comprise light-source system (103), target (104), parallel light tube (105), area array CCD camera (106) and image capturing system (107);
Target (104) is placed on the focal plane of parallel light tube (105), the coaxial placement of optical axis of parallel light tube (105) and area array CCD camera (106);
Be radiated on target (104) after light-source system (103) produces even light, then through parallel light tube (105) and area array CCD camera (106), be imaged on the focal plane of area array CCD camera (106), form the image of target (104), the imaging results of image capturing system (107) to area array CCD camera (106) carries out acquisition and processing;
Target (104) comprises 100 asterisms, the first calibration line (101) and the second calibration line (102), and described 100 asterisms are respectively the first asterism (1) to the 100 asterism (100);
First asterism (1) is all identical to the 100 asterism (100) shape and size, and is square light hole, and the length of side of square light hole is 0.9 times of standard length L; Described L=(f
col/ f
cam) d, wherein f
colfor the focal length of parallel light tube (105), f
camfor the focal length of area array CCD camera (106), d is detector cells spacing in area array CCD camera (106); First calibration line (101) and the second calibration line (102) are rectangle light hole, and the width of rectangle light hole is 0.9 times of standard length L, and length is greater than 5 times of standard length L;
First asterism (1) is respectively to the 100 asterism (100), the first calibration line (101) and the coordinate of the second calibration line (102) in target (104) plane right-angle coordinate XOY:
The apex coordinate in the first calibration line (101) the rectangle structure upper left corner is (-20L, 80L); The apex coordinate in the second calibration line (102) the rectangle structure upper left corner is (80L, 200L); The coordinate of the first asterism (1) is (0,0); The coordinate of the i-th asterism is (a19.9L, b19.9L), wherein a be i divided by 10 complementing part to subtract 1, b be i divided by 10 integral part, 1<i<100; The coordinate of the 100 asterism (100) is (179.1L, 179.1L) point; Described asterism coordinate is the coordinate in the asterism square structure upper left corner;
The true origin O of described target (104) plane right-angle coordinate XOY is the summit that the first asterism (1) square structure is positioned at the upper left corner, the positive dirction of X-axis is that the first asterism (1) points to the second asterism (2), and the positive dirction of Y-axis is that the first asterism (1) points to the 11 asterism (11);
Described target (104) size length and width are all greater than 300L.
2. the measurement mechanism of a kind of area array CCD camera point spread function according to claim 1, it is characterized in that: the first asterism (1) in described target (104) is to the 100 asterism (100), the first calibration line (101) and the second calibration line (102) printing opacity, remainder is light tight, and light transmission part and lightproof part contrast are not less than 100:1.
3. utilize a measuring method for the area array CCD camera point spread function of measurement mechanism described in claim 1, it is characterized in that step is as follows:
(1) image capturing system (107) constantly adjusts the position of target (104) while gathering target (104) image, until first calibration line (101) of target (104) is positioned on the same row of image array, second calibration line (102) is positioned at image array with in a line simultaneously, the position of fixing now target (104);
(2) time shutter of installation surface array CCD camera (106), the first asterism (1) is made to the scope of the 100 asterism (100) gray-scale value to be in the picture: [0.5K, 0.6K]; Utilize image capturing system (107) to collect the image of the target (104) under P frame current exposure time, described K is saturated gray-scale value, P be greater than 100 positive integer;
(3) neighbor pixel of pointwise to the asterism i on X frame target (104) image is sampled, and is specially:
Make the coordinate of this asterism i in image array for (x, y), then sample to its neighbor pixel (x+n, y) and (x, y+n), described n is integer, and-N≤n≤N; Described i is positive integer, and 1<=i<=100; Described N is positive integer, and N >=10;
The sequence length obtained of sampling is 2N+1, and wherein, the sampled point gray value sequence identical with the y coordinate of asterism i is x
i-N, x
i-N+1, x
i-N+2..., x
i, x
i+1, x
i+2..., x
i+N-1, x
i+N, the sampled point gray value sequence identical with the x coordinate of asterism i is y
i-N, y
i-N+1, y
i-N+2..., y
i, y
i+1, y
i+2..., y
i+N-1, y
i+N; If identical about the gray-scale value of the point-symmetric sampled point of asterism i, i.e. x
i-1=x
i+1, x
i-2=x
i+2, x
i-3=x
i+3, x
i-N=x
i+N, and y
i-1=y
i+1, y
i-2=y
i+2, y
i-3=y
i+3, y
i-N=y
i+N, then choosing this point sequence is impact point sequence, enters step (4); Otherwise return step (3) to process next frame image;
(4) according to the full trap electron number M of area array CCD camera (106) and image quantization figure place bs, the impact point sequence obtained in step (3) is converted to electron number sequence, described e-book sequence is
described transfer process is specifically by formula:
Provide, wherein x is the gray-scale value of sampled point, x
efor electron number;
(5) the electron number sequence obtained in step (4) is normalized, after obtaining normalization electron number sequence, utilizes Gaussian function N (μ
1, μ
2, σ
1, σ
2) carry out matching, obtain X two field picture Gaussian distribution point spread function variances sigma
1and σ
2;
Described normalization electron number sequence is by formula:
Provide, in formula, x ' is normalized electron number sequence,
(6) method of each two field picture in P two field picture under current exposure time according to step (4) ~ step (5) is processed, obtain the Gaussian distribution point spread function variance of each two field picture, finally obtain Gaussian distribution point spread function variance sequence σ
p1and σ
p2, to σ
p1and σ
p2make histogram distribution statistics, obtain histogram sequence, and this histogram sequence matching is obtained gauss of distribution function N (μ
h1, μ
h2, σ
h1, σ
h2), N (0,0, σ
h1, σ
h2) be the point spread function of area array CCD camera (106);
(7) utilize the imaging data of point spread function to area array CCD camera (106) of the area array CCD camera (106) obtained in step (6) to carry out image restoration, improve Remote Sensing Image Quality.
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