(PECL imagick 2.0.0)
Imagick::adaptiveThresholdImage — Selects a threshold for each pixel based on a range of intensity
Selects an individual threshold for each pixel based on the range of intensity values in its local neighborhood. This allows for thresholding of an image whose global intensity histogram doesn't contain distinctive peaks.
Width of the local neighborhood.
Height of the local neighborhood.
The mean offset
Returns TRUE on success.