This is another use of AI, this is an image I took over the Brisbane River and in strict B&W … and a JPEG to boot. I uploaded the image to https://colourise.sg/#colorize and you can see the result below. The result is about 90% accurate with the only real difference being that the color of the river water was olive brown …
It is a deep learning colouriser prototype specifically for old Singaporean photos but, my goodness, it does a wonderful job on modern images.
You can then download the result and do the cleaning up.