You can usually define force and background colors in the Terminal, so you could force black on white. But then again someone can redefine the colors in their terminal.
Some terminal emulators also support rgb; so a smart QR code program should be able to do it.
> Some terminal emulators also support rgb
* Most. Even cmd does.
No, generally not. Some QR scanners will scan "inverted" codes, but it is outside of the spec.
I usually just select the qr code in the terminal to invert it and then scan it :)
Officially you do need to have the ‘dead space’ white area around the symbol as well or it won’t scan easily.
The 2015 spec clearly call for support for both dark over light and light over dark, and doesn't constrain light and dark to black and white.