Usually the maximum filter can remove negative impulsive noise and the minimum filter can remove positive impulsive noise effectively.However, both of them invalidate to mixed impulsive noise.

• 极大滤波器通常能有效地滤除图象中的负脉冲噪声，而极小滤波器可以滤除正脉冲噪声，但两者均对混合型脉冲噪声失效。