Adds an adaptive blur filter to image. The intensity of an adaptive blur
depends is dramatically decreased at edge of the image, whereas a standard
blur is uniform across the image. This method is available if Imagick has been compiled against ImageMagick version 6.2.9 or newer.
Parameters
radius
The radius of the Gaussian, in pixels, not counting the center pixel.
Provide a value of 0 and the radius will be chosen automagically.
sigma
The standard deviation of the Gaussian, in pixels.