SAR image despeckle method based on probability model and NSDT
A probabilistic model and image technology, applied in the field of image processing, can solve the problems of loss of SAR image details and edge information, not fully considering the geometric characteristics of SAR images and statistical characteristics of SAR images, and achieve the effect of fully filtering out speckle noise in homogeneous areas
Inactive Publication Date: 2014-06-04
XIDIAN UNIV
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Although this patent application has the advantage of maintaining better detail information in the target area of the denoised SAR image and smoother homogeneous areas, it still has the disadvantage that the patent application does not fully consider the geometric characteristics of the SAR image and the SAR image in the non-uniform environment. Due to the statistical properties of the downsampled directional wave transform domain, the details and edge information in the despeckled SAR image will be partially lost
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[0037] The present invention will be further described below in conjunction with the accompanying drawings.
[0038] Refer to attached figure 1 , the concrete steps of the present invention are as follows:
[0039] Step 1: Input image.
[0040] Input an optional SAR image to be speckled. The SAR image to be speckle-removed used in the embodiment of the present invention is as follows figure 2 (a) and image 3 as shown in (a), figure 2 (a) is the SAR image of the field image to be despotted selected from the SAR image database, and its size is 256×256, image 3 (a) is the SAR image of the airport image to be despeckled selected from the SAR image library, and its size is 256×256.
[0041] Step 2: Non-subsampled directional wave transform.
[0042] The input SAR image to be despeckled is subjected to non-subsampled directional wave transformation with a scale of L, and high frequency subband coefficients and low frequency subband coefficients at different scales are obt...
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The invention discloses an SAR image despeckle method based on a probability model and NSDT. The SAR image despeckle method solves the problems that in the prior art, a margin and detail information of an SAR image after despeckle are not insufficiently maintained, and pseudo lines appear in a homogeneous area of the SAR image after despeckle. The SAR image despeckle method specifically comprises the following steps that (1) an image is input, (2) non-subsample direction wave transformation is conducted, (3) tag masks of high-frequency subband coefficients are obtained, (4) a likelihood ratio is obtained, (5) a priori ratio is obtained, (6) the high-frequency subband coefficients after despeckle are obtained, (7) non-subsample direction wave inverse transformation is conducted, and (8) the image is output. According to the SAR image despeckle method based on the probability model and the NSDT, statistical properties of an SAR image in a non-subsample direction wave transformation domain can be effectively captured, a margin and detail information of the SAR image after despeckle can be clearly maintained, and speckle noise in a homogeneous area of the SAR image to be subjected to despeckle can be effectively filtered out.
Description
technical field [0001] The present invention belongs to the technical field of image processing, and further relates to a SAR image speckle removal based on a probability model and non-subsampled directionlet transform (Nonsubsampled Directionlet, NSDT) in the field of synthetic aperture radar (Synthetic Aperture Radar, SAR) image speckle removal technology method, the invention can be used to remove speckle noise in SAR images. Background technique [0002] Synthetic Aperture Radar (SAR) is a high-resolution microwave coherent imaging radar, which has all-weather and all-time imaging characteristics and contains a large number of signal features. With the continuous development of SAR image processing technology, it has been widely used in military and civilian fields. However, due to the coherent imaging mechanism of SAR images, the image is generally polluted by speckle noise, which brings troubles to the post-processing of SAR images. Therefore, the method of SAR image ...
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IPC IPC(8): G06T5/00
Inventor 白静焦李成刘斌高艺菡王爽李阳阳马文萍马晶晶
Owner XIDIAN UNIV