DokuWiki

The level of a bandlet chooses the available range. The maximum level, 63, will choose -65536..65536; lowering the level by one will decrease the range by a factor of 2^(1/3), so decreasing the level by 3 will shrink the range by a factor of 2. As an example, the level 15 will choose the range -1..1. The range is then divided into equally sized intervals according to the quantization precision, and the center of each of these intervals will be the value represented by the quantized coefficient.

For example for a precision code of 2, there will be five intervals. If the level is 15, the intervals will be assigned to:

1. -1 to -3/5 (centered at -4/5)
2. -3/5 to -1/5 (centered at -2/5)
3. -1/5 to +1/5 (centered at 0)
4. +1/5 to +3/5 (centered at +2/5)
5. +3/5 to +1 (centered at +4/5)

As the quantized coefficients are -2,-1,0,1,2, the interval centers are obviously accessed by coeff*2/5 in this case.