I am working on mod for a game called Stellaris, and part of my project requires me to create colour-shifted versions of certain assets within the game. I'm, however, struggling with one set of images I need to modify and was hoping that someone might be aware of an easier way for me to do it. For context, I am creating two new "Fallen Empires", all of which share the same models and textures, aside from colouration, each of which uses a unique set of colours. (Gold and teal, bronze and blue, black and red, silver and orange, ect.)
The attached image is what I am attempting to edit for use in one of these new Fallen Empires; I am seeking to add a white and red faction to contrast the black and red one that exists in game, however, I am struggling with the manipulation. I want to keep the red from this images windows as it is, while shifting the black metallic buildings to a white colouration. I've attempted to use a few plugins to help me with this, but all my attempts have resulted in problems that has left me rather frustrated.