Rank Replacement Filter

Accurate Image Manipulation for Desktops

# Rank Replacement Filter

# Description

> Rank based replacement in 3x3 convolution, removes noise while preserving edges. Eight neighbors are sorted and if the center pixel is out of the current rank-range it is replaced by the nearest (either min or max) of the selected rank. All settings of this filter are more gentle than a Median filter.

# Selection Dropdown

> 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

> 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.

# Author

> Timo Autiokari. Homepage: Accurate Image Manipulation for Desktops

# Usage and Distribution Rights

> Free to download and use, distribution prohibited.

# Filter Engine

> FilterFormula v 1.1, by ATS/Graphics