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Re: Clearview



	In reply to the queries on CLEARVIEW, allow me to try & explain the basic
principles. It's all to do with sampling theory. If you want an image of a given
resolution, you don't just sample at that resolution, but need to sample higher.
(As taught by a Mr. Nyquist).
	In practical sampling systems, the higher you can sample at, the better,
as long as you have the techniques to sensibly down sample to the final
resolution that you want.
	Many observers note that down-converted High Definition video looks
better than a simputaneous standard definition version of the same work (because
of the above)
	But how does this apply to telecine?

	Well scanning in telecines is a 'black art', but what the 'Clearview'
system (I think) does is use the digital deflection system oversample the scene
(i.e. sample at a higher than necessary rate for D-1 or Rec 601 format), and
then 'sample down' to the required resolution.

	For those tekkies who want to know more, I presented a paper at the
Montreux ITS Symposium in 1995 on sampling for Post Production work, which is in
the printed symposium papers.

	Note that the above techniques only work for real sampling systems.
Mathematically 'upsampling' a signal, manipulating it, And then 'downsampling'
as some equipment manufacturers do, gets you nothing.

	Note that the Clearview explanation is my 'own guess', and not 'insider
info'. Exactly what Dave Walker does, only he knows.

Peter Stansfield
Wavecrest Systems Ltd.