Calculate Aspect Ratio

function findAspectRatio(int $width, int $height) {
  // search for greatest common divisor
  $greatestCommonDivisor = static function ($width, $height) use (&$greatestCommonDivisor) {
    return ($width % $height) ? $greatestCommonDivisor($height, $width % $height) : $height;
  };

  $divisor = $greatestCommonDivisor($width, $height);

  return $width / $divisor . ':' . $height / $divisor;
}