(PECL imagick 2.0.0)
Imagick::reduceNoiseImage — Smooths the contours of an image
$radius
   )Smooths the contours of an image while still preserving edge information. The algorithm works by replacing each pixel with its neighbor closest in value. A neighbor is defined by radius. Use a radius of 0 and Imagick::reduceNoiseImage() selects a suitable radius for you.
radius
     
   成功时返回 TRUE .
  
错误时抛出 ImagickException .