PHP mark faces in images

face.php

<?php

if (extension_loaded("facedetect")) {
  echo "facedetect extension loaded \n";
} else {
  echo "facedetect extension not loaded, can't do face detect \n";
}

$file = "haarcascade_frontalface_alt.xml";

exec("rm generated/*");

foreach (glob("original/*.jpg") as $image) {
	$count = \face_count($image, $file);
	$detect = \face_detect($image, $file);
	echo $image . " - " . $count . PHP_EOL; 

	list($width, $height) = getimagesize($image);

	$draw = "";
	$all_x1 = array();
	$all_y1 = array();
	$all_x2 = array();
	$all_y2 = array();
	foreach ($detect as $face) {
		$from_x = $face['x'];
		$from_y = $face['y'];
		$to_x = $face['x'] + $face['w'];
		$to_y = $face['y'] + $face['h'];
		$draw .= "rectangle $from_x,$from_y $to_x,$to_y ";

		$all_x1[] = $face['x'];
		$all_y1[] = $face['y'];
		$all_x2[] = $face['x'] + $face['w'];
		$all_y2[] = $face['y'] + $face['h'];
	}

	$box = "";
	if ($count > 0) {
		$x1 = min($all_x1);
		$y1 = min($all_y1);
		$x2 = max($all_x2);
		$y2 = max($all_y2);
		$box = "-fill none -strokewidth 1 -stroke green -draw  \"rectangle $x1,$y1 $x2,$y2\" ";


		$center_x = $x1 + (($x2-$x1)/2);
		$center_y = $y1 + (($y2-$y1)/2);
		$x1 = $center_x-15;
		$y1 = $center_y-15;
		$x2 = $center_x+15;
		$y2 = $center_y+15;

		$box .= " -fill \"rgba( 255, 215, 0 , 0.5 )\" -stroke none -strokewidth 0 -draw  \"rectangle $x1,$y1 $x2,$y2\" ";

	}

	$newImage = "generated/" . basename($image);
	exec("convert $image -fill none -strokewidth 1 -stroke red -draw \"$draw\" $box $newImage");
}