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 colorize photos as a hobby and have posted a few on Reddit. When picking a color it’s a process. For me it’s all about context and light levels. Light levels are one of the easiest problems that will make a colorized photo look weird. A bright color being added to a part of the photo that was originally dark or vice versa will just make it look abnormal.

My process for picking colors tends to go like this

1. Research – find color photos or descriptions of the subject to use as a template. I’ve spent many hours looking up tiny details like military service medals.
2. Balance – If research doesn’t work, find colors that match the overall look of the photo
3. Guess – If neither 1 nor 2 work, just throw a color on there and hope for the best (make sure your light levels match up)

I had one photo of a building from the 1930s I worked on for about a month. My research told me it was a brick building from the 1800s to the current day. I kept trying to add red brick colors to it and it always looked weird and too bright. After a month or so, I noticed the department store that occupied the building from the 1920s to 1940s always painted their other buildings white. I had been trying to add a dark red brick color to a white building and it just looked weird. I ended up scrapping my work on that photo and moved on because all the buildings on the street were some form of white or grey.