In Star Trek Voyager, Tom Paris sometimes runs a holodeck simulation called "Captain Proton".
The simulation is similar to that of 1950's U.S. serials.
One of the most notable things about the simulation is that everything is in black and white: including the people using it.
For example, here are Tom and B'Elanna in the simulation:
This is easily created behind the scenes by desaturating the image, or filming in black and white.
But in-Universe, how does the holodeck change the colour of Tom, B'Elanna, and their uniforms?
I could understand the holodeck simply creating props in the right colours, but how does it change the physical people?
Is there any in-Universe explanation for this?