Talk:Room at the Bottom (Dad's Army)

Re-colouring

The article says vaguely (as does the Radio Times) "the black and white film frames actually contain the original colour data"...how - where? DavidFarmbrough (talk) 01:29, 12 December 2008 (UTC)

Okay in very brief terms a colour television picture is actually a very detailed black and white picture with a cruder colour overlay. The two components are separate. When the black & white version (and many other telerecordings) were made, interference from the colour signal manifested itself as "chroma dots" embedded in the film. These can produce interference when played back electronically, but are usually filtered out by modern telecine operators. (There was, in fact, a filter device that could be used to stop the chroma dots forming back in the 1970s, but the problem was considered so minor it wasn't used when making many telerecordings. There's at least one Doctor Who episode that only exists in black & white that doesn't have the dots.) This Guardian article explains the basics: http://www.guardian.co.uk/technology/2008/mar/06/research.bbc Note that it's from much earlier in the year when the recovery process was much less advanced. Timrollpickering (talk) 02:34, 12 December 2008 (UTC)

P.S. Also the audio for the episode has been taken from an off-air recording made by a fan at the time of the original transmission because it has better quality than the audio (I presume an optical soundtrack) on the film recording. See http://news.bbc.co.uk/1/hi/england/7780021.stm for a brief piece (and clip of the colour). Timrollpickering (talk) 16:50, 12 December 2008 (UTC)

Thanks for that, Timroll. I was imagining a Monochrome telecine pointed at a colour monitor and picking up the position of the different dots, but I thought that didn't make sense as you would naturally use a monochrome monitor, however they did do some odd things! DavidFarmbrough (talk) 04:26, 16 December 2008 (UTC)