Adding MathMap - download the file below.
MathMap PluginTo install the Mathmap filter follow these directions PRECISELY or it will not work.
Unzip the download
There are two folders in the zip
MM_Add_2_plug-ins AND
mathmap
1) mathmap MUST be placed in the gimp-painter-2.8\.gimp-2.8 folder
2) All files INSIDE the MM_Add_2_plug-ins folder MUST go in the gimp-painter-2.8\.gimp-2.8\plug-ins folder
Now restart Gimp Painter and you should have mathmap
You will find Mathmap under Filters > Generic > Mathmap
G'MIC is as simple as installing into the gimp-painter-2.8\plug-ins folder.
You will find G'MIC under Filters>G'MIC