Those of us who unwittingly leave coffee stains, tend to leave more than one and at different concentrations (color of stain) so I'd like to see a bit more complexity in the image...
I think what we really need is a coffee stain plotter.
It it like a coffee vending machine that overflows the cups?
I think it would have a bit more precision.
Some people would like intricate coffee stain patterns, me thinks.