Due to a policy of “junking” video tapes in the 1960s and 70s, the original colour versions of all episodes of The Mind of Evil were lost, with only black and white copies remaining in the archives. Two types of colour restoration were used on this release:
Colour recovery was used on episodes 2-6, where the B&W tapes retained the original colour information, hidden in their signal. These were restored by Richard Russell of the Colour Recovery Working Group.
Manual colourisation was needed for episode 1, where due to the original colour-to-B&W transfer settings, no hidden colour information existed. Stuart Humphryes manually recoloured every fifth frame (out of 36,000!) in Photoshop, and the information in these “key frames” was then extrapolated out over subsequent frames.