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Re: Green Light and lower Colour Resolution

The discussion between Paul Grace, Michael Reichel and others gives me the
opportunity for an additional contribution.


First of all, let me introduce myself:
In successfull cooperation with Brad Hunt, Arthur Cosgrove, Ray Godden and
the teams at KODAK USA and UK  I was one of the BTS guys pushing the
predecessor of the SPIRIT as project manager. In the last four years I was
responsible for  ALL  the steadiness activities of this fine system. It was
a nice time and I have to thank my team.  Since April 1st  I am no longer
with PHILIPS.


Regarding lower resolution in colour signals seems to be a drawback only at
first glance:

1. Creating lower colour resolution by extending the effective pixel size
four times gives a better S/N with the same factor.

2. In telecine systems some bandlimitation in colour channels is helpfull
because going through the non linearities of the CRT-Gamma precompensation
results in broader signal spectrum. Luma is less sensitive than Chroma
against disturbances, ringing, etc. Same situation in analog and in
digital.

3. Key signal in 4:4:4:4 or with even higher clock rate doesn´t mean that
the signal itself has full bandwidth. Soft keysignals (bandlimited
characteristic) often give better results because of smooth transistions
and because of noise reduction in the key signal.

4. Aperture correction and contour correction can make the higher
frequencies much noisier (triangular noise). Comparing visual FX work with
higher S/N and  lower bandwidth  vs. lower S/N with full bandwidth shows
more edge business in the second approach.

It would be nice to have an additional show down between SPIRIT and  other
telecine or scanner systems  regarding visual FX results.


Bert Eiberger 


from the German telecine region 
now independant and no longer funded by PHILIPS.
_________________________________________________
Phone             +49-6154-525 66
Fax                   +49-6154-631174
e-mail              Bert_Eiberger at compuserve.com

Address         Am Muehlberg 40
                          D-64 372 Ober-Ramstadt
                          Germany
________________________________________________   

 

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