Recently watched this video showing colour restoration of a Black & White film. Which software did they use for this purpose? Any guess?
From the youtube video description you linked:
The in-house developed and customized cutting edge software tools provide better image quality and colors very close to the original.
When colorizing film, filmmaker's will use a variety of commercial and custom developed tools. That mix of tools is often treated as proprietary information and is not widely discussed. For example, the team responsible for recently colorizing historical footage for the Smithsonian Channel did "not rely on a single commercial product, but rather a combination of software from Adobe PhotoShop, DaVinci Resolve and more."