function checkPaths()
 {
     $version = explode('.', PHP_VERSION);
     $phptag = "php" . $version[0];
     self::$phptag = "php" . $version[0];
     self::$result1dir = "test-suite" . DIRECTORY_SEPARATOR . "results1-{$phptag}";
     self::$result2dir = "test-suite" . DIRECTORY_SEPARATOR . "results2-{$phptag}";
     self::$diffdir = "test-suite" . DIRECTORY_SEPARATOR . "diffs";
     self::$testdir = "test-suite" . DIRECTORY_SEPARATOR . "tests";
     self::$referencedir = "test-suite" . DIRECTORY_SEPARATOR . "references";
     if (!file_exists(self::$result1dir)) {
         mkdir(self::$result1dir);
     }
     if (!file_exists(self::$result2dir)) {
         mkdir(self::$result2dir);
     }
     if (!file_exists(self::$diffdir)) {
         mkdir(self::$diffdir);
     }
     self::$compare = null;
     // NOTE: This path will change between systems...
     $compares = array("/usr/bin/compare", "/usr/local/bin/compare", "test-suite" . DIRECTORY_SEPARATOR . "tools" . DIRECTORY_SEPARATOR . "compare.exe");
     foreach ($compares as $c) {
         if (file_exists($c) and is_executable($c)) {
             self::$compare = $c;
             break;
         }
     }
     if (!file_exists(self::$compare)) {
         throw new Exception("Compare path doesn't exist (or isn't executable) - do you have Imagemagick? \n");
     }
 }