A simple tool to batch convert images using Gimp 2.10 to apply a set palette that you have imported into gimp. Just run the batch script from a terminal in a folder and all PNG and GIF files in that directory will be exported to a new folder named output in the same directory. The default palette is called dkpal. You can change this by opening the batch file in a text editor and change the line PALETTE="dkpal" to match your palette name or in gimp save the palette as dkpal.