I have this image:
What's the easiest way to convert the background from black to white?
The quickest way.
right-click >> view image to see it larger)
Alternatively, here are the steps:
Image >> Adjustments >> Selective color
Black: slider all the way to the left.
If you don't want the numbers to turn white (or anything else for that matter), make sure you do NOT select them (by selecting everything else)
Granted, still a few mistakes, but there's no perfect "easy" way, unfortunately it'll take a little work to get rid of any nuances.