If I take portraits against a white background I like to use a colorchecker passport to ensure that my subjects come out at the end of my workflow looking 'true to life'.
The problem is that due to whatever reasons, my white background sometimes comes out looking slightly grey.
Is there a way to whiten the background without interfering with the colour of the subject? I could just up the white level etc. but that would obviously apply to my subject as well.
I have PS and LR but prefer to use LR.
To add some clarity to this post: I am specifically asking about modifying the background colour in lightroom or photoshop whithout it applying to the subject.