@BrianDixon is 100% correct, if this is a raster image an editor like gimp or photoshop is the most powerful way to get this done. If you are unable to install a editor or are otherwise not very savvy with image editing there are simple one off tools to help.
Pine tools has an amazing array of small helper widgets. Here’s one for inverting colors.
If this is a vector image then it’s a bit more complex but not too difficult there either. Just let us know.