Eli5: How do photo restoration artists know the supposed colors of greyscale images?

Question

Are the colors based purely on their assumptions/imagination, or do the greyscale images retain some sort of data that tells what color on what part?

In: 641

Answer 1

I don’t remember the values, but there used to be a trick in Photoshop where adjusting the HSB sliders just right would do it almost on the first try, so much so that I didn’t even have to look at it while I was doing it.