(PECL imagick 2.1.0)
Imagick::mergeImageLayers — Merges image layers
$layer_method
   )
   Merges image layers into one. This method is useful when working with image
   formats that use multiple layers such as PSD. The merging is controlled using
   the layer_method which defines how the layers are merged.
   This method is available if Imagick has been compiled against ImageMagick version 6.3.7 or newer.
  
layer_method
       One of the Imagick::LAYERMETHOD_* constants
      
   Returns TRUE on success.
  
Throws ImagickException on error.