If you know a person who is 70 years old, they were 20 in 1975 - color photos existed back then.
replyEvery grayscale photo of someone famous has already been colorized during the past 50 years. If there are only grayscale photos of you, you were probably born before 1900, and all your friends or your children (who might want to colorize your photo) are probably dead, too.
1. Improving the colourisation algorithms has value, it might be that the available colourised photos of celebrities have inaccurate colours or are of poorer quality than say, one done with a diffusion model that can be instructed about the colours of certain objects
reply2. Don’t forget about B&W films! Getting automatic methods to be consistent over a long length is still not 100% solved. People are very interested in seeing films from WW1 and WW2 in colour, for instance.
3. Plenty of people (myself included) have relatives in their 80s or 90s. Or maybe someone wants to see their ancestors from the 19th century in colour for whatever reason?
Color photos existed but color film and processing was very expensive (and while mono film development "middle school student can do at home" for a generation, home color work wasn't a thing until late 80s/early 90s as far as I recall.) So in practice, I personally have childhood pics of my dad with his mom and sister - that were shot black and white but colorized by being hand painted, and this was pretty common...
reply> If you know a person who is 70 years old, they were 20 in 1975
replyBloody hell, warn people before you post things like that.