Well it doesn't have numbers but its the nearest type of technique I could compare to, repainting historic photos!
I used to do all my photo colourisation in Photoshop but I now find it easier and even more enjoyable to do them in Procreate on my iPad, the Apple Pencil destroys the Mouse in useability!!
I love bringing these old photos to life and trying to imagine what they would look like with today's eyes, every colour I do a separate layer for, so this finished painting/restoration has 76 layers in total, it was a 4hr 15min project, with a lot of time spent tweaking the painted colours to look as real as possible.

Clacton Pier 1900's (Essex, UK)

and lastly........

Clacton Pier 1886 (Essex, UK)

Just another thing that can be created in Procreate along with the 3D model painting just released in 5.2
Thanks for travelling back in time with me, more coming soon......
Martin