Hi folks,
This is verging on being off-topic even for this section of the forum but I thought I'd share an interesting article describing how conventional "colourisation" (remember some of those pretty awful early efforts?) of black and white film can be combined with a technique which relies on extracting colour sub-carrier signals which were originally present in broadcast TV material but subsequently "lost" when that material was transferred to monochrome film. Obviously such a technique is only needed when the original colour master has been lost but that has happened more than you'd think, unfortunately.
Anyway, courtesy of the
Doctor Who Restoration Team web-site, the article in question can be found at
Dalek War Boxset and a clickable example of how the two techniques can complement each other can be seen below, neatly illustrating how the rather flat skin-tone variations were made much more natural by using the extra information from the recovered colour sub-carrier:

......................Colourised...............................................Recovered sub-carrier........................................Combined
Bob.