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Method and device for speckle noise filtering in SAR images
Method and device for speckle noise filtering in SAR images
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机译：SAR图像中斑点噪声滤波的方法和装置
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摘要
A method of filtering SAR images obtained with a Synthetic Aperture Radar (SAR) from the speckle noise is described, said method comprising:- a first step of modeling the speckle noise of at least one set of pixels (x) of the SAR image by means of a gamma statistic (20) with radiometric resolution given by Rr=10log101+σμ, where Rr is the radiometric resolution and µ and σ are the average and standard deviations of the gamma statistic, respectively,- a second step of transforming at least one plurality of pixels (x) of the at least one set of pixels of the SAR image into a plurality of filtered pixels (x') by means of a data transfer function given by x'=Gα,β(1-x)=(1-(1-x)α)β, where x' is the filtered pixel value, x is the pixel value of the SAR image, α and β are real parameters,- setting the invariance of the average µ of the gamma statistic for the filtered image, comprising said plurality of filtered pixels x', so as µ'=(1-(1- µ)α)β ≡ µ, where µ' is the value of the average of the gamma statistic (30) related to the filtered image; such a setting fixes the value of the parameter β according to the parameter α by the formula βα=logμlog(1-1-μα,- setting the standard deviation σ' of the gamma statistic related to the filtered image as σʹ=σ/N, with N being the Equivalent Number of Looks which is intended to be obtained at the end of the filtering process,- setting σ'=σ·Φ, where Φ is the decrease factor of the initial deviation σ due to the filtering process,- setting said factor Φ equal to the transfer function derivative Gα,β about the point 1-µ, thus obtaining Φα=αμ⋅log μ⋅1-μα-1log1-1-μα(1-1-μα≡1N, from which the value of the parameter α is determined,- constructing the filtered image with the intensity values of the plurality of filtered pixels x', (Fig. 1)
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