OT: BBC videotapes (Was: DIY Kryoflux or Catweasle

[Peter Corlett]

On Thu, May 25, 2017 at 10:33:41AM -0700, Fred Cisin via cctalk wrote:
[...]
> Fortuitously, the B&W film was sharp enough to be able to make out the dot
> mask of the CRT! That made possible the development of a new technique -
> computer recognition of which pixels were the original RGB dots of the image!
> That, unlike manual colorisation, results in reasonably exact recreation of
> the original colors.

I don't know if you're describing yet another way colour was retrieved from
telecine recordings, or a faulty recollection of the detail of James Insell's
work at BBC R&D.

James's moment of inspiration was when he was watching some old Doctor Who
telerecordings that had been telecined back and had caused what appeared to be
artifact colour. He realised that the film recording contained enough detail to
capture the colour subcarrier.

The bit that was combined genius and perspiration was figuring out the phase of
the colour signal, since the colour burst never made it into the recording.
Without that, one can't reliably separate U from V and the hue will be
essentially random.