Cause of neediness of inverting colors

Some wild/weird ideas come to mind.

1. Maybe viewing a some document that uses weird colors might be easier to see if you invert it.

2. If the stuff you are looking at is mostly white then perhaps flipping it to black might be easier on a portable battery if it didn't have to light up all those pixels to make a white background.

I did say "wild/weird" 😉

Why are you asking about this?

For some of us with sensitivity to bright light, or indeed just slightly impaired vision, the colour reversal can be invaluable for reading, especially if poor combinations of text and background colours have been used.

I use it often, as indeed I use the zoom feature often.