(No version information available, might only be in SVN)
Imagick::getImageAlphaChannel — Gets the image alpha channel
Gets the image alpha channel value. The returned value is one of the alpha channel constants. This method is available if Imagick has been compiled against ImageMagick version 6.4.0 or newer.
Returns a constant defining the current alpha channel value. Refer to this list of alpha channel constants.
Throws ImagickException on error.