针对一般双边滤波器定义中的像素灰度相似度函数易受图像噪声影响,不能很好地表征像素之间的实际相似性的问题,设计了一个基于次序统计量的像素灰度相似度函数.基于图像中相邻像素之间的相关性,可近似地将某像素的1环邻域所有像素的灰度视为该像素灰度的n(n≤9)次观测值,并定义为n-次序统计量.依据两像素灰度的n-次序统计量的欧氏距离定义它们的灰度相似度.该相似度函数结合了像素1环邻域灰度分布的统计属性,能较好地抑制噪声的影响.仿真实验验证了所提出基于次序统计量像素灰度相似度的双边滤波算法具有良好的滤波特性.
The classic similarity function adopted in general bilateral filter is yet subject to image noise,it fails frequently to reflect the grey similarity between two pixels.This paper proposes a new estimate of the similarity between two pixels based on the ordered statistics of their grey values.Due to the correlation among the adjacent image pixels,the grey values of all pixels in the 1-ring neighborhood of the concerned pixel can be regarded as its multiple observations,which is referred to as its n-ordered statistics value.We re-define the similarity between two pixels in the bilateral filter according to the Euclidean distance of their n-ordered statistics values.This novel estimate of similarity is based on the grey distribution within the 1-ring neighborhood of the two pixels thus is able to restrain the noise influence.Combining the new grey similarity estimate with the metric of spatial proximity suggests a robust bilateral filter.Experiments results demonstrate a better performance of the proposed filter than that of current approaches.