The method of speckle reduction is widely used in synthetic aperture radar (SAR) imagery over the last three decades. The SAR images are inherently speckled in nature. Speckle noise is a granular pattern distribution, usually modeled as a multiplicative noise that affects the SAR images, as well as all coherent images. Other SAR related problems are also discussed in this paper. Therefore, despeckling approaches are needed to improve the quality of SAR images. However, there is a trade-off between speckle reduction and the preservation of fine details in the despeckled SAR image. The reduction of the speckle noise without losing the fine details of the SAR image is a diffucult task. However, many despeckling methods have been discussed to reduce the speckle noise from the SAR images. Each method has their own norms, advantages and disadvantages. This article contains a review of some major work in the field of SAR image despeckling. Often, scientists and scholars have faced the struggle to understand the pattern distribution of the speckle noise in SAR images. Hence, a brief details about radar, SAR imaging, speckle noise in SAR images and the prevalent approaches of SAR image despeckling are reviewed here. The advantages and disadvantages of SAR image despeckling approaches are also analysed and discussed.

在过去的三十年中，减少斑点的方法广泛用于合成孔径雷达（SAR）图像中。SAR图像本质上具有斑点。斑点噪声是一种颗粒状的图案分布，通常建模为影响SAR图像以及所有相干图像的乘性噪声。本文还讨论了其他与SAR相关的问题。因此，需要采用去斑点方法来提高SAR图像的质量。但是，在斑点减少和去斑点SAR图像中保留精细细节之间需要权衡。在不损失SAR图像的精细细节的情况下减少斑点噪声是一项艰巨的任务。然而，已经讨论了许多去斑点方法以减少来自SAR图像的斑点噪声。每种方法都有自己的规范，优点和缺点。本文回顾了SAR图像去斑领域中的一些主要工作。通常，科学家和学者们一直在努力理解SAR图像中斑点噪声的模式分布。因此，这里回顾了有关雷达，SAR成像，SAR图像中的斑点噪声以及SAR图像去斑点的流行方法的详细信息。SAR图像去斑方法的优缺点也进行了分析和讨论。