In the "Day of the Doctor"
trailer, we get a close-up of the first Doctor. The clarity and level of detail of the Doctor's face obviously exceeds that of any video footage of the first Doctor's stories, and it looks more clear than most if not all publicity stills that I've seen as well.
How in the world did they accomplish this? Was his face Photoshopped from scratch, using available visual references as guides, but ultimately improvising on the rest of the details?