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spot vs line analyser for telecine
- To: "INTERNET:telecine at sun.alegria.com" <telecine at sun.alegria.com>
- Subject: spot vs line analyser for telecine
- From: Dick Hobbs <Dick_Hobbs at compuserve.com>
- Date: Mon, 8 Sep 1997 01:23:05 -0400
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- Resent-Date: Sun, 7 Sep 1997 22:29:18 -0700 (PDT)
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There is perhaps something in JP's thoughts about the difference between
CCDs and flying spots, but I am not sure he is quite there yet.
For a start, I am not convinced by the concept of a "pixel of the film". I
am sure JP didn't mean us to take this literally, but it is worth repeating
that you are at far higher resolution than telecines before you start
worrying about the picture elements of crystals on the film.
What I have sometimes considered, but have never really investigated
properly, is this. CCDs have what we can regard as perfectly even
illumination over the whole film frame, but scan it into rectilinear pixels
because of the shape of the line array and its photosites. A flying spot
telecine uses a spot of light, which is brightest at its point of focus
but, because of the nature of the phosphors, is not hard-edged: light
levels fall off around the centre of the spot.
Is this why, to some eyes, CCD telecines have a video look? Because they
are generating rigid, rectangular, hard-edged pixels, whereas flying spot
telecines are inherently smoother?
And, if so, does this mean that SCAN'dAL from the TWiGi people, which
changes the shape of the URSA spot, will give the most natural
anti-aliasing of all, because it will provide a smooth transition from line
to line, pixel to pixel?
Thanks to Kat Dalton for support of the TIG
TIG subscriber count is 846 on Sun Sep 7 22:29:11 PDT 1997
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