CN105427286A - Gray scale and gradient segmentation-based infrared target detection method - Google Patents
Gray scale and gradient segmentation-based infrared target detection method Download PDFInfo
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Abstract
The invention discloses a gray scale and gradient segmentation-based infrared target detection method. The method comprises the following steps: 1) calculating a gradient image Phi(x, y) by utilizing an original image Forg; 2) carrying out non-maximum value inhibition on the Phi(x, y) to obtain an image Phi1(x, y); 3) carrying out edge linking and edge closing judgement by utilizing the Phi1(x, y), and calculating a candidate target area Pos1; 4) selecting a local image Floc according to the Pos1 and segmenting the Floc to obtain a candidate target area Pos2; and 5) calculating an optimum target area Pos according to a formula (as shown in the specification).
Description
Technical field
The present invention relates to infrared image processing field, a kind of particularly infrared target detection method split based on gray scale and gradient of applicable hardware real-time implementation
Background technology
Infrared imaging, as the important supplement means of radar system, has passive detection, is not easily found, the feature such as all weather operations, is widely used at Military and civil fields.In recent years, infrared imaging detection becomes the focus and emphasis of Chinese scholars research, proposes many valuable detection methods.The people such as Zhang Qiang propose to split based on the infrared small object of local maximum, treat detected image carry out enhancing process by Gaussian template; For the deficiency that fixed size filtering core in traditional filtering method shows Dim targets detection, Gong Junliang proposes a kind of method for detecting infrared puniness target based on Scale-space theory; The people such as Li Qiuhua adopt the Dual band IR subject fusion of D-S evidence theory to detect; For the imaging characteristic of variable resolution Small object infrared under cloudy background, Zhao Xiao proposes a kind of method for detecting infrared puniness target based on Scale-space theory; A kind of method that the people such as LiuZH propose images match realizes compensating detector motion, uses method of difference to realize moving object detection.
There is following shortcoming in existing target detection technique: the scene bad adaptability of (1) most detection algorithm, if scene changes is large, can reduce the precision of target detection; (2) under complex scene, target detection capabilities is poor; (3) But most of algorithms adopts single feature to detect, poor robustness.
Summary of the invention
Goal of the invention: technical matters to be solved by this invention is for the deficiencies in the prior art, provides a kind of infrared target detection method split based on gray scale and gradient.
In order to solve the problems of the technologies described above, the invention discloses a kind of infrared image object detection method, comprising the following steps:
(1) original image F is utilized
orgcompute gradient image
(2) right
carry out non-maximal value suppression, obtain image
(3) utilize
carry out edge conjunction, edge closure judges, calculated candidate target area Pos
1;
(4) according to Pos
1choose topography F
loc, to F
locsplit, obtain candidate target region Pos
2;
(5) according to Pos=Pos
1∩ Pos
2calculate optimal objective region Pos.
The present invention is based in the infrared target detection method of gray scale and gradient segmentation, by Sobel operator compute gradient image
The present invention is based in the infrared target detection method of gray scale and gradient segmentation, edge closure judges whether comprehensive row, column direction closure is object edge point to evaluate current point.Decision criteria comprises: 1) line direction closure, column direction closure are greater than threshold value T simultaneously
1, 0≤T
1≤ 1; 2) if the i-th leftmost effective value position of row is Col
mini (), rightmost effective value position is Col
max(i), Col
deci () > T represents the i-th behavior effectively row, otherwise the i-th behavior inactive line, wherein, Col
dec(i)=Col
max(i)-Col
min(i), T is threshold value, 3≤T≤10, then line direction closure computing formula is as follows:
3) if jth row effective value position is topmost Row
minj (), effective value position is bottom Row
max(j), Row
decj () > T represents that jth is classified as effective row, otherwise jth is classified as invalid row, wherein, and Row
dec(j)=Row
max(j)-Row
min(j), T is threshold value, 3≤T≤10, then column direction closure computing formula is as follows:
The present invention is based in the infrared target detection method of gray scale and gradient segmentation, determined the segmentation threshold Q of gray level image by maximum variance between clusters (" microcomputer information ", the 26th volume 12-2 phase in 2010);
The present invention is based in the infrared target inspection method of gray scale and gradient segmentation, pass through Pos
1and Pos
2optimal objective region Pos is obtained with computing.
The present invention compared with prior art, has following remarkable advantage: 1) target detection is carried out in employing bicharacteristic (gray scale, gradient), Algorithm robustness is strong; 2) split local gray level image, Iamge Segmentation degree of accuracy is high; 3) gray threshold is calculated by scene adaptive, algorithm scene strong adaptability; 4) there is not high exponent arithmetic(al) and labyrinth, algorithm operation quantity is little, is easy to hardware real-time implementation.
Accompanying drawing explanation
To do the present invention below in conjunction with the drawings and specific embodiments and further illustrate, above-mentioned and/or otherwise advantage of the present invention will become apparent.
Fig. 1 is process flow diagram of the present invention.
Fig. 2 a is the original image of embodiment.
Fig. 2 b is the gradient segmentation result of embodiment.
Fig. 2 c is the intensity slicing result of embodiment.
Fig. 2 d is the final detection result of embodiment.
Embodiment
The invention discloses a kind of infrared target detection method split based on gray scale and gradient, comprise the following steps:
(1) original image F is utilized
orgcompute gradient image
(2) right
carry out non-maximal value suppression, obtain image
(3) utilize
carry out edge conjunction, edge closure judges, calculated candidate target area Pos
1;
(4) according to Pos
1choose topography F
loc, to F
locsplit, obtain candidate target region Pos
2;
(5) according to Pos=Pos
1∩ Pos
2calculate optimal objective region Pos.
In step (1), use Sobel operator compute gradient image
In step (2), right
carry out " non-maximal value suppression ": in the 3*3 neighborhood centered by pixel data, be defined as by gradient direction centered by pixel data, horizontal direction, the direction of vertical direction and positive and negative miter angle is total to the line of four direction.All directions this direction and pixel data neighborhood pixels compare, and determine local maximum.
data | ||
If the gradient direction of the pixel data of center belongs to vertical direction, then the neighborhood pixels of pixel data and vertical direction is compared, if pixel value data is not maximal value, set to 0.
In step (3), edge closure judges whether comprehensive row, column direction closure is object edge point to evaluate current point.Decision criteria comprises: 1) line direction closure, column direction closure are greater than threshold value T simultaneously
1, 0≤T
1≤ 1; 2) if the i-th leftmost effective value position of row is Col
mini (), rightmost effective value position is Col
max(i), Col
deci () > T represents the i-th behavior effectively row, otherwise the i-th behavior inactive line, wherein, Col
dec(i)=Col
max(i)-Col
min(i), T is threshold value, 3≤T≤10; 3) if jth row effective value position is topmost Row
minj (), effective value position is bottom Row
max(j), Row
decj () > T represents that jth is classified as effective row, otherwise jth is classified as invalid row, wherein, and Row
dec(j)=Row
max(j)-Row
min(j), T is threshold value, 3≤T≤10;
In step (4), topography F
loccomprise Pos
1rectangular area, utilize maximum variance between clusters to F
loccarry out intensity slicing, obtain candidate target region Pos
2;
In step (5), pass through Pos
1and Pos
2optimal objective region is obtained with computing.
Embodiment 1
Present embodiment discloses a kind of infrared target detection method split based on gray scale and gradient, comprise the following steps:
(1) original image F is utilized
orgcompute gradient image
(2) right
carry out non-maximal value suppression, obtain image
(3) utilize
carry out edge conjunction, edge closure judges, calculated candidate target area Pos
1;
(4) according to Pos
1choose topography F
loc, to F
locsplit, obtain candidate target region Pos
2;
(5) according to Pos=Pos
1∩ Pos
2calculate optimal objective region Pos.
In step (1), use Sobel operator compute gradient image
In step (2),
carry out " non-maximal value suppression ", gradient direction is defined as AA line direction (i.e. AA-data-AA), BB line direction (i.e. BB-data-BB), CC line direction (i.e. CC-data-CC), DD line direction (i.e. DD-data-DD) four direction, all directions neighborhood pixels compares, determine local maximum, as shown in the table:
DD | CC | BB |
AA | data | AA |
BB | CC | DD |
If the gradient direction of the pixel value data of center belongs to DD-data-DD, then pixel value data and pixel value DD is compared, if pixel value data is not maximal value, set to 0.
In step (3), edge closure judges whether comprehensive row, column direction closure is object edge point to evaluate current point.Decision criteria comprises: 1) row, column direction closure is greater than threshold value T simultaneously
1; 2) for line direction closure, row difference Col
deci () > T represents the i-th behavior candidate target region, T is threshold value; 3) for column direction closure, the row difference Row between two row
decj () > T represents that jth is classified as candidate target region, T is threshold value.
In step (4), topography F
loccomprise Pos
1rectangular area, utilize maximum variance between clusters to F
loccarry out intensity slicing, obtain candidate target region Pos
2;
In step (5), pass through Pos
1and Pos
2optimal objective region is obtained with computing.
Embodiment 2
Composition graphs 1, illustrates the infrared target detection method that the present invention is based on gray scale and gradient segmentation below with example.The number of pixels 640 × 512 of infrared image, frame frequency 50HZ.Digital signal passes to the special image disposable plates of FPGA+DSP framework by optical fiber, and the infrared target detection method based on gray scale and gradient segmentation realizes in dsp processor, and the processing time is less than 20ms, and meet the demand of process in real time, concrete implementation step is as follows:
(1) original image F is obtained
org, utilize Sobel operator compute gradient image
F
orgbe 14-bit digital picture, obtain gradient image by Sobel operator
(2) right
carry out non-maximal value suppression, obtain image
(3) calculate line direction closure, hypothetical target edge at image 82nd ~ 87 row, the row minimum value Col that target is expert at
min, row maximal value Col
maxbe respectively Col
min={ 122,118,119,118,120,121} and Col
max={ 129,125,129,128,127,123}.The row difference that target is expert at is Col
deccan be expressed as:
Col
dec=Col
max-Col
min
={7,7,10,10,7,2}
As threshold value T=3, can be calculated by decision criteria, line direction closure is 83.3%.
Calculated column direction closure, hypothetical target edge arranges at image 82nd ~ 87, the row minimum value Row of target column
min, row maximal value Row
maxbe respectively Row
min={ 122,118,119,118,120,121} and Row
max={ 129,125,129,128,127,123}.The row difference of target column is Row
deccan be expressed as:
Row
dec=Row
max-Row
min
={7,7,10,10,7,2}
As threshold value T=3, can be calculated by decision criteria, column direction closure is 83.3%.
(4) right
when carrying out edge conjunction, setting high threshold is 0.85, and Low threshold is 0.34, carries out edge conjunction, closed judgement operation, obtain candidate target region Pos by high and low threshold value
1;
(5) the intensity slicing threshold value utilizing maximum variance between clusters to obtain is 896, utilizes intensity slicing threshold value to local Image Segmentation Using, obtains candidate target region Pos
2;
(6) Pos is passed through
1and Pos
2optimal objective region is obtained with computing.
Embodiment 3
In Fig. 2, Fig. 2 a represents original image, and Fig. 2 b represents gradient segmentation result, and Fig. 2 c is intensity slicing result, and Fig. 2 d is final detection result.Image shows, and the infrared target detection method target detection based on gray scale and gradient segmentation that the present invention proposes is accurately high.
The invention provides a kind of infrared target detection method split based on gray scale and gradient; the method and access of this technical scheme of specific implementation is a lot; the above is only the preferred embodiment of the present invention; should be understood that; for those skilled in the art; under the premise without departing from the principles of the invention, can also make some improvements and modifications, these improvements and modifications also should be considered as protection scope of the present invention.The all available prior art of each ingredient not clear and definite in the present embodiment is realized.
Claims (6)
1., based on the infrared target detection method that gray scale and gradient are split, it is characterized in that, comprise the following steps:
Step (1), utilizes original image F
orgcompute gradient image
Step (2), to gradient image
carry out non-maximal value suppression, obtain image
Step (3), utilizes image
carry out edge conjunction, edge closure judges, calculated candidate target area Pos
1;
Step (4), according to candidate target region Pos
1choose topography F
loc, to topography F
locsplit, obtain candidate target region Pos
2;
Step (5), according to formula Pos=Pos
1∩ Pos
2calculate optimal objective region Pos.
2. a kind of infrared target detection method split based on gray scale and gradient according to claim 1, is characterized in that, in step (1), uses Sobel operator compute gradient image
3. a kind of infrared target detection method split based on gray scale and gradient according to claim 1, is characterized in that, in step (2), to gradient image
carry out non-maximal value and suppress process;
Non-maximal value suppresses process to comprise: in the 3*3 neighborhood centered by pixel data, be defined as by gradient direction centered by pixel data, and the direction of horizontal direction and vertical direction and positive and negative miter angle is total to the line of four direction; All directions this direction and pixel data neighborhood pixels compare, and determine local maximum; If the gradient direction of the pixel data of center belongs to vertical direction, then the neighborhood pixels of pixel data and vertical direction is compared, if pixel value data is not maximal value, set to 0.
4. a kind of infrared target detection method split based on gray scale and gradient according to claim 1, it is characterized in that, in step (3), edge closure is used to judge that comprehensive row, column direction closure is to judge whether current point is object edge point, meets the following conditions simultaneously:
1) line direction closure, column direction closure are greater than threshold value T simultaneously
1, 0≤T
1≤ 1;
2) if the i-th leftmost effective value position of row is Col
mini (), rightmost effective value position is Col
max(i), Col
deci () > T represents the i-th behavior effectively row, otherwise the i-th behavior inactive line, wherein, Col
dec(i)=Col
max(i)-Col
min(i), T is threshold value, 3≤T≤10;
Wherein, line direction closure computing formula is as follows:
3) if jth row effective value position is topmost Row
minj (), effective value position is bottom Row
max(j), Row
decj () > T represents that jth is classified as effective row, otherwise jth is classified as invalid row, wherein, and Row
dec(j)=Row
max(j)-Row
min(j), T is threshold value, 3≤T≤10;
Wherein, column direction closure computing formula is as follows:
5. a kind of infrared target detection method split based on gray scale and gradient according to claim 1, is characterized in that, in step (4), and topography F
loccomprise Pos
1rectangular area, utilize maximum variance between clusters to F
loccarry out intensity slicing, obtain candidate target region Pos
2.
6. the infrared target detection method split based on gray scale and gradient according to claim 1, is characterized in that, in step (5), by topography Pos
1with topography Pos
2optimal objective region is obtained with computing.
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