CN110032968A - Denoising method based on dual-tree complex wavelet and adaptive semi-soft threshold model - Google Patents
Denoising method based on dual-tree complex wavelet and adaptive semi-soft threshold model Download PDFInfo
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- CN110032968A CN110032968A CN201910286915.6A CN201910286915A CN110032968A CN 110032968 A CN110032968 A CN 110032968A CN 201910286915 A CN201910286915 A CN 201910286915A CN 110032968 A CN110032968 A CN 110032968A
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- G06—COMPUTING; CALCULATING OR COUNTING
- G06F—ELECTRIC DIGITAL DATA PROCESSING
- G06F2218/00—Aspects of pattern recognition specially adapted for signal processing
- G06F2218/02—Preprocessing
- G06F2218/04—Denoising
- G06F2218/06—Denoising by applying a scale-space analysis, e.g. using wavelet analysis
Abstract
The denoising method based on dual-tree complex wavelet and adaptive semi-soft threshold model that the present invention relates to a kind of, this method include the following steps: with the optical signalling of the sample frequency acquisition reflection of setting;Dual-tree complex wavelet decomposition is carried out to optical signalling, calculates the variance of noisy optical signalling each layer after the wavelet sub-band coefficient of each layer and double tree wavelet decompositions;Lower threshold value and upper threshold value are obtained using Bayesian adaptation semi-soft threshold model and carry out dual-tree complex wavelet inverse transformation using the wavelet sub-band coefficient within the scope of lower threshold value and upper threshold value, the optical signalling after obtaining noise reduction.The present invention combines the good characteristic of dual-tree complex wavelet transform the advantages of adaptive semi-soft threshold filter can effectively remove signal noise, can preferably filter out the noise in signal.
Description
Technical field
The invention belongs to IR reflected signals noise-removed technology fields, in particular to a kind of based on dual-tree complex wavelet and adaptive
Answer the denoising method of semi-soft threshold model.
Background technique
IR reflected signals will receive such as sensor oscillation, the shadow of the reasons such as electronic device interference during generation
It rings, leads to the digital signal quality obtained after conversion decline, generate a large amount of miscellaneous peaks in waveform.In order to guarantee the correct of subsequent processing
Property, it needs to carry out denoising to signal.The application of signal denoising technology expands to biomedical, Information Center from aeronautical field
The every field such as, Resources and environmental sciences, astronomy, physics, industry, agricultural, national defence, education, art and industry, to warp
Ji, military, culture and daily life generate significant impact.Therefore, the research of signal denoising technology has of crucial importance
Application value.
There are many kinds of the methods of signal denoising, is broadly divided into airspace and two kinds of frequency domain.Traditional signal denoising mainly exists
What spatial domain was realized, main method has mean filter, median filtering and Wiener filtering.But the denoising effect of these methods is not
Ideal, signal the phenomenon that will appear distortion although noise can be removed, after denoising.Frequency domain denoising method be by signal by
Space field transformation denoises the transformation coefficient in frequency domain to frequency domain, then the coefficient after denoising is carried out inverse transformation and returns to sky
Between domain achieve the purpose that denoising.Common method has Fourier transformation, wavelet transformation and double tree wavelet transformations etc.." dual density is double
The seismic signal noise reduction [J] of tree complex wavelet domain statistical model " (Du Yuefeng, Wang Jinju HeFei University of Technology journal (natural science
Version), 2018,41 (7)), each sampled point wavelet systems after the double tree wavelet decompositions of each layer are obtained using dual-tree complex wavelet transform method
Numerical value and variance, then the wavelet coefficient values for estimating signal are reconstructed by dual-tree complex wavelet inverse transformation, after obtaining noise reduction
Signal.Wavelet coefficient is filtered out the disadvantages of the method are as follows uniform threshold is easy to be excessive, causes distorted signals.
Summary of the invention
It is gone the technical problem to be solved in the present invention is to provide a kind of based on dual-tree complex wavelet and adaptive semi-soft threshold model
The good characteristic of dual-tree complex wavelet transform and adaptive semi-soft threshold filter can be effectively removed signal noise by method for de-noising, this method
The advantages of combine, can preferably filter out the noise in signal.
In order to solve the above-mentioned technical problem, the denoising side of the invention based on dual-tree complex wavelet and adaptive semi-soft threshold model
Method includes the following steps:
Step 1: with the sample frequency f of settingcAcquire the optical signalling of reflection, 250000≤fc≤ 1500000Hz, sampling
Between be divided into 0~200;
Step 2: carrying out dual-tree complex wavelet decomposition to the optical signalling of step 1 acquisition, and set the highest level of decomposition
N, N≤10;Calculate the variance of noisy optical signalling each layer after the wavelet sub-band coefficient of each layer and double tree wavelet decompositions;
Step 3: obtaining lower threshold value λ using Bayesian adaptation semi-soft threshold model1With upper threshold value λ2;
1) noise variance is estimated according to D.L.Donoho formula
Wherein Yi,jThe wavelet sub-band coefficient of ith sample point after indicating the double tree wavelet decompositions of optical signalling jth layer,
Median(|Yj,i|) be jth layer wavelet sub-band absolute coefficient intermediate value;
2) according to the variance of formula (2) calculating optical signal
WhereinFor the variance of the jth layer after the double tree wavelet decompositions of optical signalling;
3) lower threshold value λ is determined1With upper threshold value λ2;
λ1=min (TB,TG);λ2=max (TB,TG)
Wherein
Step 4: lower threshold value λ will be less than1Be greater than upper threshold value λ2Wavelet sub-band coefficient filter out, and utilize lower threshold value λ1With
Upper threshold value λ2Wavelet sub-band coefficient in range carries out dual-tree complex wavelet inverse transformation, the optical signalling after obtaining noise reduction.
The preferred f of the sample frequencyc=1200000Hz, sampling interval preferably 50.
Beneficial effects of the present invention: dual-tree complex wavelet transform has Time Frequence Analysis characteristic, while having approximate Horizon
Motion immovability and multi-direction selectivity.The present invention proposes a kind of based on dual-tree complex wavelet transform and adaptive medium-soft threshold filtering side
Method can choose suitable threshold value according to Decomposition order faster, noise is effectively filtered out.
Detailed description of the invention
Invention is further described in detail with reference to the accompanying drawings and detailed description.
Fig. 1 is the denoising method flow chart of the invention based on dual-tree complex wavelet and adaptive semi-soft threshold model.
Fig. 2 a is the noiseless curve of original optical signal.
Fig. 2 b is the contaminated curve of noisy optical signalling.
Fig. 2 c is using the optical signalling filter curve after de-noising of the present invention.
Fig. 3 is using the optical signalling filter curve after the method de-noising of prior art dual density dual-tree complex wavelet.
Specific embodiment
As shown in Figure 1, the denoising method of the invention based on dual-tree complex wavelet and adaptive semi-soft threshold model includes following
Step:
Step 1: the sample frequency f with PCI capture card to setcThe optical signalling for acquiring reflection, chooses f herec=
1200000Hz, sampling interval selection 50;
Step 2: carrying out dual-tree complex wavelet decomposition to the optical signalling of step 1 acquisition, and set the highest level of decomposition
N, N≤10;Calculate noisy optical signalling each layer after the wavelet sub-band coefficient of each layer and double tree wavelet decompositions variance (referring to
" the seismic signal noise reduction [J] of dual density dual-tree complex wavelet domain statistical model ", Du Yuefeng, Wang Jinju HeFei University of Technology journal
(natural science edition), 2018,41 (7));
Step 3: obtaining lower threshold value λ using Bayesian adaptation semi-soft threshold model1With upper threshold value λ2;
1) noise variance is estimated according to D.L.Donoho formula with robust intermediate value device
Wherein Yi,jThe wavelet sub-band coefficient of ith sample point after indicating the double tree wavelet decompositions of optical signalling jth layer,
Median(|Yj,i|) be jth layer wavelet sub-band absolute coefficient intermediate value;
2) according to the variance of formula (2) calculating optical signal
WhereinFor the variance of the jth layer after the double tree wavelet decompositions of optical signalling;
3) lower threshold value λ is determined1With upper threshold value λ2;
λ1=min (TB,TG);λ2=max (TB,TG)
WhereinN is Decomposition order;
Step 4: lower threshold value λ will be less than1Be greater than upper threshold value λ2Wavelet sub-band coefficient filter out, and utilize lower threshold value λ1With
Upper threshold value λ2Wavelet sub-band coefficient in range carries out dual-tree complex wavelet inverse transformation (referring to " dual density dual-tree complex wavelet domain counts
The seismic signal noise reduction [J] of model ", Du Yuefeng, Wang Jinju HeFei University of Technology journal (natural science edition), 2018,41
(7)) optical signalling after, obtaining noise reduction.
As shown in Fig. 2 a, Fig. 2 b, Fig. 2 c, Fig. 3, the denoised signal obtained after being denoised using the present invention to original signal, with
The dual density dual-tree complex wavelet method of the prior art is compared, the present invention using root-mean-square error (RMSE) and signal-to-noise ratio (SNR) and
Smoothness (R) is used as evaluation index, and root-mean-square error is the smaller the better, and signal-to-noise ratio is the bigger the better, and smoothness variation is the smaller the better.Table
1 is the result under different evaluation index.
The denoising Indexes of Evaluation Effect of 1 different evaluation mode of table
Claims (2)
1. a kind of denoising method based on dual-tree complex wavelet and adaptive semi-soft threshold model, it is characterised in that include the following steps:
Step 1: with the sample frequency f of settingcAcquire the optical signalling of reflection, 250000≤fc≤ 1500000Hz, sampling interval
It is 0~200;
Step 2: carry out dual-tree complex wavelet decomposition to the optical signalling of step 1 acquisition, and set the highest level N, N of decomposition≤
10;Calculate the variance of noisy optical signalling each layer after the wavelet sub-band coefficient of each layer and double tree wavelet decompositions;
Step 3: obtaining lower threshold value λ using Bayesian adaptation semi-soft threshold model1With upper threshold value λ2;
1) noise variance is estimated according to D.L.Donoho formula
Wherein Yi,jThe wavelet sub-band coefficient of ith sample point after indicating the double tree wavelet decompositions of optical signalling jth layer, Median
(|Yj,i|) be jth layer wavelet sub-band absolute coefficient intermediate value;
2) according to the variance of formula (2) calculating optical signal
WhereinFor the variance of the jth layer after the double tree wavelet decompositions of optical signalling;
3) lower threshold value λ is determined1With upper threshold value λ2;
λ1=min (TB,TG);λ2=max (TB,TG)
Wherein
Step 4: lower threshold value λ will be less than1Be greater than upper threshold value λ2Wavelet sub-band coefficient filter out, and utilize lower threshold value λ1With upper-level threshold
Value λ2Wavelet sub-band coefficient in range carries out dual-tree complex wavelet inverse transformation, the optical signalling after obtaining noise reduction.
2. the denoising method according to claim 1 based on dual-tree complex wavelet and adaptive semi-soft threshold model, feature exist
In fc=1200000Hz, sampling interval selection 50.
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Cited By (2)
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CN110969656A (en) * | 2019-12-10 | 2020-04-07 | 长春精仪光电技术有限公司 | Airborne equipment-based laser beam spot size detection method |
CN112528853A (en) * | 2020-12-09 | 2021-03-19 | 云南电网有限责任公司昭通供电局 | Improved dual-tree complex wavelet transform denoising method |
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WO2007137484A1 (en) * | 2006-05-11 | 2007-12-06 | Shanghai Jiao Tong University | A channel estimation method and the device thereof |
CN105182418A (en) * | 2015-09-11 | 2015-12-23 | 合肥工业大学 | Seismic signal noise reduction method and system based on dual-tree complex wavelet domain |
CN107184187A (en) * | 2017-07-03 | 2017-09-22 | 重庆大学 | Pulse Wave Signal Denoising processing method based on DTCWT Spline |
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US20050259889A1 (en) * | 2004-05-21 | 2005-11-24 | Ferrari Ricardo J | De-noising digital radiological images |
WO2007137484A1 (en) * | 2006-05-11 | 2007-12-06 | Shanghai Jiao Tong University | A channel estimation method and the device thereof |
CN105182418A (en) * | 2015-09-11 | 2015-12-23 | 合肥工业大学 | Seismic signal noise reduction method and system based on dual-tree complex wavelet domain |
CN107184187A (en) * | 2017-07-03 | 2017-09-22 | 重庆大学 | Pulse Wave Signal Denoising processing method based on DTCWT Spline |
Cited By (4)
Publication number | Priority date | Publication date | Assignee | Title |
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CN110969656A (en) * | 2019-12-10 | 2020-04-07 | 长春精仪光电技术有限公司 | Airborne equipment-based laser beam spot size detection method |
CN110969656B (en) * | 2019-12-10 | 2023-05-12 | 长春精仪光电技术有限公司 | Detection method based on laser beam spot size of airborne equipment |
CN112528853A (en) * | 2020-12-09 | 2021-03-19 | 云南电网有限责任公司昭通供电局 | Improved dual-tree complex wavelet transform denoising method |
CN112528853B (en) * | 2020-12-09 | 2021-11-02 | 云南电网有限责任公司昭通供电局 | Improved dual-tree complex wavelet transform denoising method |
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