Some simple python script to convert an image into a set of ground marker points to be used with Runelite's Ground Markers Plugin import feature.

Take an image (preferrably somewhat small), get the World Location or Region info of the South-Western most tile where the image is to be placed in-game and feed those in to the code. If you can run Runelite in Developer mode, you can also get this info from the Tile Location dev tool.

You can get the Region info by exporting a marker from Runelite and looking at its values.

No guarantees this will work correctly in instances, especially "modular" ones like CoX and Player-owned Houses. The Tile Location dev tool will be incorrect for this purpose.