Even if one of the ideas are working,this is not tonemapping friendly.As you know i want to load a image in the compositing tonemapper without any object setup if that makes sence.
I wonder why we dont have a simple texture coordinate in the compositing ?
My idea was something like this
or this
as overlay of the loaded image with its own xy coordinates
edit ,i have rendered a plane with AOV and UV output.Now i have to add the math plotter.