Criterion for designing adaptive filters based on segregation of grey levels in SAR images

In boundary zones (edges) in synthetic apertue radar (SAR) images, there is no logical (scientific) explanation for employing the kernel average for approximating the backscattering factors in central kernel pixels. Therefore, adaptive filters are used to decrease the speckles in these images. These filters prevent the averaging process in the edges when smoothing the images (noise reduction) in homogeneous areas, thus causing reduction of lucidity in the edges. In most existing adaptive filters, the variation coefficient (coefficient of variation) is used to detect the edges in the images. An alternative factor is introduced to detect the edges in intensity images; by employing this factor, an adaptive filter is presented. The results of evaluating this filter and comparing it with other adaptive filters illustrate that it has excellent competency in speckle reduction, and hence it protects the edges of the images during the filtering process. using various assessment measures (such as signal-to-noise ratio and mean absolute error), the obtained results provide evidence that the proposed filtering process outperforms other classical methodologies.