Path: utzoo!attcan!utgpu!jarvis.csri.toronto.edu!cs.utexas.edu!tut.cis.ohio-state.edu!ucbvax!ucsd!ucrmath!kevin
From: kevin@ucrmath.UCR.EDU (kevin lund)
Newsgroups: comp.graphics
Subject: Re: digitizing images
Message-ID: <2968@ucrmath.UCR.EDU>
Date: 8 Dec 89 05:57:41 GMT
References: <129@tobler.UUCP> <1989Dec7.134309.11032@imax.com>
Reply-To: kevin@ucrmath.UUCP (kevin lund)
Organization: University of California, Riverside
Lines: 20

In article <1989Dec7.134309.11032@imax.com> dave@imax.com (Dave Martindale) writes:
    [...]
>
>And then there is the disc itself.  Watch the servo circuits in a CD
>player sometime - they are constantly making small adjustments in focus
>and tracking because your average CD is not flat, and does not have its
>"centre" hole punched in the centre.  The player NEEDS those servo
>loops operating all the time just to stay on track.  If you "froze" the
>pickup for any significant distance, it is just about guaranteed to be
>out of focus and out of alignment when the spiral tracks re-appear.
>If you only want to scan images the size of 8mm film frames, you might
>just get away with it.  But I doubt anything larger could work.

How about slaving a second head positioning mechanism to the servo
circuits of one with a real, no film taped on it CD?  Then you could
do anything you wanted on the other one - have a nice white, grooveless
background and your picture could be as big as the CD.  Or bigger if
you want; just use videodiscs instead.  Of course, I believe the
original intent was to come up with a cheap scanner and this is getting
a bit expensive...