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.
function adaptiveBlurImage($image_path, $radius, $sigma, $channel)
{
    $imagick = new \Imagick(realpath($image_path));
    $imagick->adaptiveBlurImage($radius, $sigma, $channel);
    header("Content-Type: image/jpg");
    echo $imagick->getImageBlob();
}