A non-local speckle reduction method for sar images based on ratio distribution
A ratio distribution, non-local technology, applied in the field of image processing, can solve problems such as poor approximation estimation error, achieve the effect of suppressing speckle noise and improving the effect of speckle reduction
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Embodiment 1
[0065] In the imaging process of SAR, there will inevitably be the interference of coherent speckle noise. This kind of speckle noise will seriously affect the understanding and interpretation of SAR images. Therefore, before processing the SAR image, preprocessing for speckle reduction is usually performed. At present, there are many methods for speckle reduction in SAR images. Traditional filtering methods such as Lee filtering, Kuan filtering, Frost filtering, etc. generally take the mean value of the local homogeneous area, and adopt a strategy of retaining the points that change quickly. The downside is that noise around edges is also preserved. In order to overcome these shortcomings, Charles et al. proposed a PPB method in 2009, which is considered to be one of the best SAR image despeckling methods currently. However, the Euclidean distance used by the PPB algorithm in the process of speckle removal for SAR images cannot be well suited for the multiplicative noise mo...
Embodiment 2
[0080] The non-local speckle reduction method for SAR images based on the ratio distribution is the same as that in Embodiment 1, wherein, step (2) calculates the central pixel block and neighboring pixel blocks Ratio distance d t1 , including the following steps:
[0081] (2a). Take pixel v s As the center, select a neighborhood of N×N size as the search area of the pixel, and take N=21 in this example;
[0082] (2b). Take pixel v s As the center, take a block of M×M size, and use the gray value matrix of each pixel in the block Indicates the central pixel block, M=7 in this example;
[0083] (2c). Remove the central pixel v in the search area s Every pixel outside v t As the center, take a block of M×M size, and use the gray value matrix of each pixel in the block Indicates the neighborhood pixel block;
[0084] (2d). Calculate the above two pixel blocks and The ratio of each corresponding pixel in:
[0085]
[0086] where v s，k and v t，k Respectivel...
Embodiment 3
[0093] The non-local speckle reduction method for SAR images based on the ratio distribution is the same as in embodiment 1-2. If the input SAR image is an intensity image in step (2) in this example, then use the intensity probability formula in step (2e):
[0094]
[0095] Calculate the central pixel block and neighboring pixel blocks The ratio distance d between t1 , that is to say, calculate the pixel point v s center pixel block and in pixels v t Neighborhood pixel block centered The ratio distance d between t1 ,
[0096]
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