private int countSafeControl() {
        return count('\t') + count('\n') + count('\r') // tab, LF, CR
                + count(0x0c) + count(0x1b);           // new page, escape
    }
Counts eight bit characters, i.e. bytes with their highest bit set.

@return count of eight bit characters
tika-core/src/main/java/org/apache/tika/detect/TextStatistics.java