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

They are making an educated guess. But they are often more muted than they should be. Experiments where colorized photos are compared to a control (photo taken in color) have shown that when photos are colorized they are often much less colorful than the original.