I made this plugin to get rid of random ink blots on scanned pages.
There are two modes, one builds clusters of pixels outside tolerance of the secondary color, the other builds clusters of pixels within tolerance of the primary color. If the cluster is within the size thresholds, it is painted over with the secondary color.
It's found under Effects/Noise
The source code is available here:
This is my first plugin (my first C# project, in fact) so it's not very advanced yet.
If you have any suggestions please tell.
Also, I couldn't find the formula Paint.Net uses to calculate tolerance, so if you know it, please tell me.
Added Clustering Modes and Linked Sliders