private function gifBlockCompare($globalBlock, $localBlock, $length)
    {
        for ($i = 0; $i < $length; $i++) {

            if ($globalBlock [ 3 * $i + 0 ] != $localBlock [ 3 * $i + 0 ] || $globalBlock [ 3 * $i + 1 ] != $localBlock [ 3 * $i + 1 ] || $globalBlock [ 3 * $i + 2 ] != $localBlock [ 3 * $i + 2 ]) {

                return 0;
            }
        }

        return 1;
    }