Summary of the invention
The objective of the invention is to overcome the deficiency of above-mentioned prior art, proposed a kind of sorting technique,, realize effectively expression radar two-dimensional image to improve the validity of characteristic of division based on multi-scale geometric analysis.
Realize that the object of the invention technical scheme comprises following process:
(1) imports the sample image collection, and each width of cloth image of sample image collection is carried out normalization;
(2) each sample image after the normalization is carried out three layers of wavelet decomposition and Contourlet decomposition, obtain a sample image corresponding respectively 10 wavelet decomposition subbands and 13 Contourlet and decompose subbands;
(3) each that obtains is decomposed subband and extract energy feature, and utilize the method for Feature Fusion that these energy features are merged;
(4) select the energy feature after the supporting vector machine algorithm is combined to classify.
Above-mentioned radar two-dimensional image sorting technique based on multi-scale geometric analysis, wherein the described method of Feature Fusion of utilizing of step (3) merges energy feature, and detailed process is as follows:
3a) with wavelet decomposition sub belt energy feature w={w1, w2 ..., w10} and Contourlet decompose sub belt energy feature c={c1, c2 ..., c13} is arranged side by side, obtain corresponding 23 subbands energy feature w1, w2 ..., w10, c1, c2 ..., c13};
3b) to the subband energy feature w1, w2 ..., w10, c1, c2 ..., c13} selects, the energy feature after the selection then is the energy feature after merging.
Above-mentioned energy feature merging method, wherein step 3b) described to the subband energy feature w1, w2 ..., w10, c1, c2 ..., c13} selects, detailed process is as follows:
3b.1) with the energy feature of subband w1, w2 ..., w10, c1, c2 ..., c13}, the series arrangement descending according to eigenwert be, and cw1, cw2 ..., cw23};
3b.2) give up 8 features that are arranged in the back, stay preceding 15 energy features as the energy feature after merging.The present invention compared with prior art has following advantage:
1. the present invention is owing to adopted the Feature Fusion technology, wavelet decomposition and Contourlet are decomposed the energy feature merging of extracting the back, make that the energy feature after merging is more effective, overcome the deficiency of feature when expression radar two-dimensional image that wavelet transformation extracts, can access better classification results.
2. the present invention has given up the part energy feature because the sub belt energy feature is side by side selected, and has reduced the dimension of energy feature, has further reduced the complexity of the inventive method, has improved performance.
Test experiments shows that classification accuracy of the present invention is 88.21%, is better than the classification accuracy 83.53% of wavelet method and the classification accuracy 84.72% of Contourlet method.
Embodiment
With reference to Fig. 1, step of the present invention is as follows:
Step 1 is imported the sample image collection, and each width of cloth image of sample image collection is carried out normalization.
Suppose that sample image collection number to be classified is the N width of cloth, be designated as (x
1, x
2..., x
N); Because what adopt is the sorting algorithm of supervised learning, i.e. supporting vector machine algorithm is so need be designated as (x as training sample image by the picked at random M width of cloth from N width of cloth image
1, x
2..., x
M); Image set (x
1, x
2..., x
N) pixel between 0~255 normalizing to 0~1, be designated as (z
1, z
2..., z
N).According to the proof of Donoho, the image after the normalization can extract more effectively feature.
Step 2 is carried out three layers of wavelet decomposition and Contourlet decomposition to each sample image after the normalization, obtains a sample image corresponding respectively 10 wavelet decomposition subbands and 13 Contourlet and decomposes.
To the sample image collection (z after the normalization
1, z
2..., z
N) carry out three layers of wavelet transformation and Contourlet conversion respectively.Sample image is concentrated j sample image z
j, carry out three layers of wavelet transformation, can obtain 10 and decompose subband; Be to this sample image z equally
jCarry out three layers of Contourlet conversion, set the maximum detail layer and get 8 direction subbands, inferior maximum detail layer is got 4 direction subbands, adds 1 approximate subband, draws the subband after corresponding 13 Contourlet decompose.
Step 3 is extracted energy feature to the decomposition subband that obtains, and the method for utilizing Feature Fusion merges the feature that wavelet decomposition subband and Contourlet decompose subband.
3a. extract the energy feature that each decomposes subband.
For the subband after decomposing, need to extract the feature of each subband, these features comprise energy feature, variance, average, Hu square, through a large amount of experiments relatively, energy feature is the most effective in these several features, so the present invention extracts energy feature.Extracting method adopts L
1Norm energy norm method:
Wherein, P * Q is for extracting the subband size of feature, and i represents the line number of the feature subband that extracts, and j represents the columns of the feature subband that extracts, coef (i, j) by the coefficient value that the capable j of i is listed as in the extraction feature subband.
3b. utilize the method for Feature Fusion that energy feature is merged.
The Feature Fusion method that adopts among the present invention is that feature is arranged side by side, increases the number of feature, needs afterwards feature is selected, and realizes the purpose of dimensionality reduction.The present invention is for simple and practical, with wavelet decomposition sub belt energy feature w={w1, and w2 ..., w10} and Contourlet decompose sub belt energy feature c={c1, c2 ..., c13} is arranged side by side, obtains energy feature { w1, the w2 of corresponding 23 subbands, ..., w10, c1, c2 ..., c13}, then to the subband energy feature w1, and w2 ..., w10, c1, c2, ..., c13} selects, and the series arrangement descending according to eigenwert is, cw1, cw2 ..., cw23} gives up 8 features that are arranged in the back, stays preceding 15 energy features as the energy feature after merging.
In the test experiments of reality, the energy feature that extracts from M width of cloth training sample image is corresponding with training sample image, is designated as training characteristics (f
1, f
2..., f
M), all N width of cloth treat that the energy feature that the classification samples image extracts is designated as characteristic of division (f
1, f
2..., f
N).
Step 4 selects the energy feature after the supporting vector machine algorithm is combined to classify.
The sorting technique of selecting among the present invention is a kind of sorting algorithm that supervision is arranged, it is the supporting vector machine algorithm, be abbreviated as SVM, this algorithm to the process that image carries out classification and Detection is: 1. with the input as sorting algorithm of the training characteristics that obtains, corresponding with it sorting algorithm output result is desirable output result, thus the training sorting algorithm; 2. in the sorting algorithm that the input of next step characteristic of division that obtains has been trained, the output of sorting algorithm is last classification results.
According to the step explanation of SVM algorithm, the present invention is as follows to the detailed process of energy feature classification:
4a. with the training characteristics (f described in the step 3
1, f
2..., f
M), and one group of desirable output result (y of this feature correspondence
1, y
2..., y
M), as the training set of SVM;
4b. with described training set substitution formula
{ k represents training characteristics (f in the formula for α, b} to obtain optimum solution
1, f
2..., f
M) ordinal number, α represents the weights of SVM, b represents the inclined to one side value of SVM;
4c. with optimum solution α, b} construct the corresponding relation of SVM input and output:
Output
SVM=sgn (α * defeated
SVM+ b) (2)
Sgn () is-symbol function wherein,
4d. with the characteristic of division (f described in the step 3
1, f
2..., f
N) input in the replacement formula (2)
SVM, the then output in the formula (2)
SVMThe value that obtains is exactly the classification results of required radar two-dimensional image.
Performance of the present invention can be tested by the classification experiments of following three radar two-dimensional images, and following experimental data has provided the average result of 20 times, 50 times and the 100 times independent operatings that circulate respectively.All experimental results all are under Windows XP service condition, and CPU obtains in MATLAB 7.0 environment for the IV 2.4GHz that runs quickly.
Experiment one: based on the radar two-dimensional image middle and small scale aircraft sample classification experiment of multi-scale geometric analysis.
This experiment is used for checking the influence of the inventive method to the classification performance of radar two-dimensional image middle and small scale aircraft sample.
For the validity of the energy feature after the present invention merges is described, the method with wavelet transformation and Contourlet conversion compares respectively.
The data set of experiment is radar two-dimensional image storehouse, and sample size is 128 * 128.230 samples have been selected in the experiment altogether, 4 class aircraft images have been comprised, the all corresponding certain fragmentary sample of every class, 9 fragmentary samples are arranged in this experiment, and when training SVM, 20 samples of picked at random are as training sample from 230 all samples, and Fig. 2 is the experiment one 4 class aircraft sample synoptic diagram that adopted.Provided the average result of three kinds of methods in the table 1, comprised test accuracy rate, repeatedly a best classification results in service and the average wrong sample number that divides among the result at 20 times, 50 times and 100 times independent operatings of circulation.
Table 1 is based on the radar two-dimensional image middle and small scale aircraft sample reason classification experiments of multi-scale geometric analysis
Data in the table 1 show, in 20 times result of circulation, the classification accuracy that sorting technique of the present invention obtains is better than other two methods, yet in the result of circulation 50 times and 100 times, result of the present invention is slightly poorer than the Contourlet method, be because specimen types is few, and the sample of selecting in this experiment is suitable for Contourlet method condition, so in experiment subsequently, increased sample number and specimen types number.
Experiment two: fairly large aircraft sample classification experiment in the radar two-dimensional image based on multi-scale geometric analysis.
This experiment is used for checking the method for mentioning among the present invention to aircraft sample classification Effect on Performance fairly large in the radar two-dimensional image, and by adopting the influence of feature selecting technology to algorithm performance among comparative descriptions the present invention of working time.
The data set of experiment is radar two-dimensional image storehouse, and size is 128 * 128.800 samples have been selected in the experiment altogether, 10 class aircraft images have been comprised, 80 samples of every class, and all corresponding certain fragmentary sample, 32 fragmentary samples are arranged in this experiment, and when training SVM, 100 samples of picked at random are as training sample from 800 all samples, and Fig. 3 is the experiment two 10 class aircraft sample synoptic diagram that adopted.Provided the average result of three kinds of methods in the table 2, comprised test accuracy rate, repeatedly a best classification results in service and the average wrong sample number that divides among the result at 20 times, 50 times and 100 times independent operatings of circulation.
Fairly large aircraft sample reason classification experiments in the radar two-dimensional image of table 2 based on multi-scale geometric analysis
Data by table 2 show that the classification accuracy that the present invention obtains is better than other two methods, under the condition that fragmentary sample exists, still can reach 90% test accuracy rate.
For feature selecting operation that the present invention the adopts influence to the inventive method is described, provided in the table 3 and taked feature selecting and do not take the influence of feature selecting working time of the present invention.
Table 3 comparison working time (unit: second)
Take feature selecting |
Do not take feature selecting |
51.68 |
72.69 |
By comparing data explanation working time of table 3, the present invention has given up the part energy feature because the sub belt energy feature is side by side selected, and has further reduced complexity, has accelerated working time.
Experiment three: fairly large mixing aircraft and naval vessel sample classification experiment in the radar two-dimensional image based on multi-scale geometric analysis.
This experiment is used for checking method of the present invention to fairly large mixing aircraft in the radar two-dimensional image and naval vessel sample classification Effect on Performance.
The data set of experiment is radar two-dimensional image storehouse, and size is 128 * 128.Selected 1000 samples in the experiment altogether, comprised 10 class aircraft images, 80 samples of every class, 800 samples altogether; 2 class ship images, 100 samples of every class, have 200 samples altogether, and all corresponding certain fragmentary sample, 40 fragmentary samples are arranged in this experiment, and when training SVM, 120 samples of picked at random are as training sample from 1000 all samples, Fig. 3 is the experiment three 10 class aircraft sample synoptic diagram that adopted, and Fig. 4 is the experiment three 2 class naval vessel sample synoptic diagram that adopted.Provided the average result of three kinds of methods in the table 4, comprised test accuracy rate, repeatedly a best classification results in service and the average wrong sample number that divides among the result at 20 times, 50 times and 100 times independent operatings of circulation.
Fairly large mixing aircraft and naval vessel sample classification experiment in the radar two-dimensional image of table 4 based on multi-scale geometric analysis
As can be seen from Table 4, the present invention can effectively classify to the image that has mixed aircraft and naval vessel, and its classification results is better than other two kinds of methods, and classification accuracy is preferably arranged.
Above-mentioned three experiments all as can be seen, Feature Fusion technology and feature selection approach that the present invention adopts can effectively overcome the deficiency that wavelet transformation is represented the radar two-dimensional image, have improved classification accuracy.In addition, three experiments among the present invention all adopt about 10% in all samples as training sample, illustrate that method of the present invention is suitable for condition of small sample, and this is highly significant for the radar image of handling other.