An adaptive median filter with a circular kernel, named as circular adaptive median filter (CAMF) is proposed in this article, for denoising of magnetic resonance imaging (MRI) images corrupted by salt and pepper noise of varying noise densities. An adaptive operation is incorporated in the proposed filter by varying the size of the circular kernel according to the requirement. The effectiveness of the CAMF is compared with six other competitive networks, i.e., conic adaptive median filter (CoAMF), decision based filter (DBF), modified switching median filter (MSWM), recursive adaptive modified filter (RAMF), plus adaptive median filter (PAMF), and cross adaptive median filter (CrAMF). The performance of all the models is analyzed using peak signal to noise ratio (PSNR) and computational time. Moreover, a non-parametric statistical test is conducted to illustrate the pair wise comparison of other filter with the proposed one. It is observed that the proposed approach has demonstrated superior performance with respect to the two performance measures.

中文翻译：

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圆形自适应中值滤波器，用于抑制MRI图像中的盐和胡椒粉噪声

本文提出了一种具有圆形核的自适应中值滤波器，称为圆形自适应中值滤波器（CAMF），用于对因噪声密度和盐和胡椒粉噪声而损坏的磁共振成像（MRI）图像进行消噪。通过根据需要改变圆形核的大小，将自适应运算结合到所提出的滤波器中。将CAMF的有效性与其他六个竞争性网络进行比较，即圆锥形自适应中值滤波器（CoAMF），基于决策的滤波器（DBF），修改后的切换中值滤波器（MSWM），递归自适应修改型滤波器（RAMF）和自适应中值滤波器（PAMF）和交叉自适应中值滤波器（CrAMF）。使用峰值信噪比（PSNR）和计算时间来分析所有模型的性能。此外，进行了非参数统计检验，以说明其他滤波器与所提出的滤波器的成对比较。可以看出，相对于两种性能指标，所提出的方法已显示出优异的性能。