基于噪声检测的中值滤器已广泛用于消除图像中的脉冲噪声。然而，在高噪声密度情况下，过多的像素被错误地分类，这个缺陷将会对图像滤波产生负面影响，为了克服这个缺陷，提出了一种上下中值型噪声检测器。基于这种噪声检测方法，又提出了一种自适应中值滤波算法。实验结果显示，该算法能够有效地消除脉冲噪声，并且保留了原始图像的更多细节。

Noise detection-based median filters have been widely adopted to reduce impulse noise in images. However, more pixels were misclassified at the high noise density. The drawback has negative effect on image filtering. In order to overcome the drawback, in this paper, the upper-lower median-type noise detector is proposed. Based on the noise detector, an adaptive median algorithm is presented. Experimental results show that the new algorithm can effectively remove the impulse noise and preserve more details of original images.