1st Rank is the same
as the common Min Max filter. It removes spurious isolated noise pixels.
2nd Rank is slightly stronger
than 1st Rank but sill preserves edges.
3rd Rank is affects to the
edges slightly.
4th Rank is almost as strong
as a Median Filter.
Adjusted setting allows the
user to specify different ranking based on the average RGB value in the
3x3 (less the center pixel) convolution matrix.
Sliders are
only effective when Adjusted mode is selected in the Selection
Dropdown (see above).
Sliders are named as
4th,
3rd,
2nd
and 1st. They define the upper average RGB level of the 3x3
matrix (less the center pixel) that the rank in question
will be applied.
E.g. if the sliders
are set as follows:
Slider 4th
set
to 20
Slider 3rd set
ot 40
Slider 2nd set
to 60
Slider 1st set
to 80
Then rank 4 will be applied
to levels 0...20, rank 3 will be applied to levels 21...40, rank 2 will
be applied to levels 41...60, rank 1 will be applied to levels 61...80
and levels 81...255 are not affected at all.
Even if it is possible
to set the sliders into what ever level the proper usage is such that slider
4th <= slider 3rd <= slider 2nd <= slider
1st.