I have an old picture postcard of DeFuniak Springs from around 1900. It was sent to my Grandmother when she was a girl from one her best friends.
I did a bit of research and learned that they were colored by hand. Once the original had been painted they were able to duplicate them in color by some process.
My mother worked for a company called Victor Animatograph. She did the colorizing of b&w photos I thought. I guess they did films, too, wish I'd asked her more about it.
A lot were produced on linen-like paper. I scanned and shared a lot of mine but they are on an old hard drive somewhere or a backup Passport that failed.
There are a lot of videos of Czarist Russia on yt that have been colorized; I assumed by hand. They look like I would expect colorized of b&w to look whereas the video tonight I wasn't prepared for the high quality of the coloring.
Thak you for your info. I don't know what to think at this point. All my various experience and never enough.