Here’s a screen shot in Lightroom, before and after view, of my not so black and white misty morning image.
The saturation slider (last slider in the adjustment panel on right hand side) was moved all the way to the left removing all colour.
In Photoshop, we can look at the pixels up close. Using the colour picker tool, we can select an area of the image to see what the colour is. I hovered the eyedropper over a grey part of the image just above and to the right of the dialogue box and clicked. I tried this in a number of areas of the image with consistent results. (When I attempted a screen shot capture to share my findings, the eyedropper vanished from the screen! The image below was shot with my iPhone!)
Did you guess the hint of colour is orange? Darker shades of orange become brown and when added to an image create a sepia or aged look.