Input values are non-linearly digitally filtered to produce as an output
value the R.sup.th-largest value among the K input values, wherein the
R.sup.th-largest value may be the median value with R=(K+1)/2. The input
values are provided in any binary fixed point number representation. A
respective selected bit of all the input values is evaluated to determine
the R.sup.th-largest bit value of this bit among the K input values, and
this gives the value of the corresponding bit of the output value. In the
input values of which the selected bit does not correspond to the
determined R.sup.th-largest bit value, all of the subsequent
less-significant bits are set as dummy bits equal to the selected bit,
which excludes these input values from being the R.sup.th-largest value
in the subsequent evaluation of the successive less-significant bits.
Then these steps are repeated for the next selected less-significant bit,
and so forth, thereby respectively determining the successive bits of the
output value. Minor modifications are necessary depending on the
particular numerical representation. The method can be used for
implementing digital filters, in particular for signal processing in
systems for object recognition.