Some related engineering genius: the artefacts created in the black and white picture by the colour signal are hardly noticeable, but they are enough to recover the colour from a black and white recording!
Only if the photo itself was in colour and broadcast in colour.
It's the other way around I was thinking of - a still shot (in black and white) of a PAL or NTSC signal would still contain enough information to decode the colour now, in retrospect.
For instance, a high resolution (still) film photo of a large high resolution TV from back in the day.
https://colour-recovery.fandom.com/wiki/The_Unofficial_Colou...