1. SAR images inevitably produce speckle, which interferes with the accurate expression of real object information and deteriorates image quality.
2. A variety of filtering methods have been proposed to suppress speckle, including spatial domain filtering, transform domain filtering, anisotropic diffusion filtering, non-local means (NL-means) filtering, and deep learning filtering.
3. This paper proposes a novel NL-means filter based on multi-directional local plane inclination angle (MDLPIA), called MDLPIA-NLM, which can better obtain weight by using a multi-directional local plane inclination angle for improved filtering effect.
The article is generally reliable and trustworthy in its presentation of the various methods used to suppress speckle in SAR images. The article provides a comprehensive overview of the different types of filters available and their respective advantages and disadvantages. The authors also provide evidence for their claims by citing relevant research papers that support their arguments. Furthermore, the authors present both sides of the argument equally when discussing the various filters available for speckle suppression.
However, there are some potential biases in the article that should be noted. For example, while the authors discuss deep learning filters as one of the options for suppressing speckle noise, they do not provide any evidence or examples to support this claim. Additionally, while they mention that anisotropic diffusion filters require multiple iterations to achieve effective results, they do not provide any details on how many iterations are typically required or how these iterations should be set up correctly. Finally, while they discuss the potential benefits of their proposed MDLPIA-NLM filter over existing methods such as NL-means filtering and PPB filter, they do not provide any evidence or examples to demonstrate this improvement in performance.