It sounds like a simple thing to do , but I'm struggling.
I have a png image of a rectangle with a transparent centre called "zero". I want to change the colour of the visible part of the image. To try and change it, I have tried using "zero.fill" but no option I try changes only the non-transparent part, or it merges the new colour with the old and stays like that.
I'm not keen on installing numpy as I wish to take the finished program to a friend who doesn't have it. Any simple suggestions welcome.