Soft proofing.

Soft proofing is simulating an output condition on screen: the file is converted through the output profile and back into the display profile, so the monitor previews what that ink, that substrate and that press can actually reach. It is worth precisely what its conditions are worth. The display has to be profiled and held at a known white point and luminance, which is what ISO 12646 covers for proofing displays; the room has to be dim enough not to wash the screen; and any physical sample compared against it has to sit under viewing light conforming to ISO 3664, not under whatever fixture is above the workstation. Two things stay outside the simulation whatever you do, and both matter on garments: surface texture, and the metamerism between an emissive screen and a reflective print. Keep the ritual and drop the conditions and you get the worst outcome on offer, which is a customer who approved a screen, a sample that does not match it, and an argument in which both parties are describing something they really saw.