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Re: resolution?




Craig,

I will not comment on the optical performance of specific systems or
telecines.  However, I believe that your question on resolution, and test
film to measure such, is extremely important.  This is also an area of
study which has occupied my attention for several years, although I claim
no specific expertise in this field.

Resolution is a complex subject which is often over simplified.  This has
always been a problem in video.  Historically, video resolution was
"measured" in video lines, or more recently, as pixels per line.  The
latter being even more insidious than the former, in that, often there are
no measurements, and the "resolution" is implied, as in; "the film was
scanned at 2K,  or the film was scanned at 4K".  Is it possible that a 1K
scan can have more resolution than a 2K scan, or that a 2K scan can have
more resolution than a 4K scan?

The answer to the above is definitely yes.

It is intuitively obvious that two imaging systems which have the same
technical specifications can have different image qualities, whether these
are film cameras and lenses, or telecines and lenses.

That a lower resolution scan can have more resolution than a higher
resolution scan has much to do with a concept known as "Modulation Transfer
Function".  If you are familiar with what a multi-burst test signal looks
like, or if you have measured frequency response of a system, or device,
with a multi-burst test signal, then you are already aware of the concept
of MTF.  The real measure of resolution is not in absolute numbers but in
relative response to specific frequencies.  For instance, in the 1920 x
1035/1080 high definition system which I am most familiar with, an ideal
system would have 100% frequency response from zero to 30Mhz.  However,
real imaging systems might have responses like the following, and still
produce excellent images; 100% to 10Mhz, 70% at 20Mhz, and less than 30% at
30Mhz. Frankly, if I could produce this kind of response, without image
enhancement, I would be very happy.

Dr. Robert Lamberts at Sine Patterns produces the test film which I use to
measure system resolution.  Sine Patterns was founded by Dr. Lamberts, an
ex-Kodak research scientist.  Sine Patterns has a web site at
"http://www.sinepatterns.com".  You will find lots of useful information on
this web site.  You can also call Bob Lamberts and ask him to provide you
with the latest pattern which he provided to me to measure our systems!
These patterns are not inexpensive.  A single frame of film ( which is
usually all that is necessary) costs over $600.  However, I believe that
being able to measure system resolution unambiguously is worth it.

As I said at the beginning of this e-mail this is a complex subject, if you
would like me to elaborate I will do so privately, or publicly, if there is
enough general interest in this subject.



At 6:16 PM 7/11/98, Craig Nichols wrote:
>Is anyone working to improve the URSA, Mark III optics?  Are the optics in
>the C Reality a quantum leap forward? Can converted machines resolve 800
>lines at the center and edges, and if so at what depth of focus modulation?
>Is there any available resolution test film to check this?  How does the
>Spirit compare in resolution?
>Craig Nichols                                   213-465-1231
>Director of Engineering                         213-465-2579 fax
>Todd-AO Video                                   craign at todd-ao.com
>Los Angeles, CA                                 craign at earthlink.net
>
>
>
>
>
>---
>Thanks to Doug Leighton, Ted Brady, & Gary Coates for support in 1998.
>No product marketing allowed on the main TIG.  Contact rob at alegria.com
>1001 subscribers in 38 countries on Sat Jul 11 18:16:28 PDT 1998
>subscribe/unsubscribe with that Subject: to telecine-request at alegria.com
>complete information on the TIG website http://www.alegria.com/tig3/

John Galt,
Vice President High Definition Technology Development
Sony Pictures High Definition Center
10202 West Washington Blvd.
Culver City
CA 90232-3195

VOICE: 310-244-4387     FAX: 310-244-3014
E-MAIL: johngalt at earthlink.net



---
Thanks to Queue Systems and Lipsner Smith for support in 1998.
No product marketing allowed on the main TIG.  Contact rob at alegria.com
1002 subscribers in 39 countries on Sun Jul 12 23:05:26 PDT 1998 
subscribe/unsubscribe with that Subject: to telecine-request at alegria.com
complete information on the TIG website http://www.alegria.com/tig3/