While I know this has come up on Twitter, here’s a variant.
Press ‘V’ to make an image convert to Black & White. Press again to go back to colour. Easy?
Now in Develop, press and hold ‘V’. It goes to grayscale.. Now release the key.. It goes back to colour.
It’s a cool way of seeing if an image works in B&W; quickly.
If you try it in Library, you’ll get what Don Ricklin calls a ‘psychedelic effect’, i.e it strobes between B&W; and colour!