code: public static function checkRequirements()
      {
          if (extension_loaded('imagick')) {
              $imagickFormats = (new \Imagick())->queryFormats('PNG');
              if (in_array('PNG', $imagickFormats, true)) {
                  return 'imagick';
              }
          }
          if (extension_loaded('gd')) {
              $gdInfo = gd_info();
              if (!empty($gdInfo['FreeType Support'])) {
                  return 'gd';
              }
          }
          throw new InvalidConfigException('Either GD PHP extension with FreeType support or ImageMagick PHP extension with PNG support is required.');
      }
docs: Checks if there is graphic extension available to generate CAPTCHA images.
  This method will check the existence of ImageMagick and GD extensions.
  @return string the name of the graphic extension, either "imagick" or "gd".
  @throws InvalidConfigException if neither ImageMagick nor GD is installed.