0 - no data (1 level, just 0)

1 - -1..1 (3 levels)

2 - -2..2 (5 levels)

3 - -3..3 (7 levels)

4 - -5..5 (11 levels)

5 - -7..7 (15 levels)

6 - -15..15 (31 levels)

7 - -31..31 (63 levels)