public function __construct()
 {
     // sobel horizontal
     parent::__construct(-1, -2, -1, 0, 0, 0, 1, 2, 1);
     //4
 }
 public function applyFilter(ImageResource $aResource)
 {
     parent::applyFilter($aResource);
 }
 public function __construct()
 {
     parent::__construct(3, 10, 3, 0, 0, 0, -3, -10, -3);
 }
 public function __construct()
 {
     parent::__construct(-1, 0, 1, -2, 0, 2, -1, 0, 1);
 }
 public function __construct()
 {
     parent::__construct(1, 2, 1, 0, 0, 0, -1, -2, -1);
 }