with android it's for the camera.
on ubuntu touch, it does nothing.
it's already ask in gitlab.
@Krille not really look closer
don't see any problem. just change image found in tool and modify it with gimp =). i used png format to be sure, but i don't try to use any other format!
I made a splash.img for fun, if you want it
you can built your own with tool
I don't know if the tool work for other device, test at your one risk