[tig] printer points exposure and ire:

Peter Swinson peter_swinson
Mon Sep 6 11:48:21 BST 2004

Dominic explains printer points well.

Just to add that the ONLY control on a telecine that comes anywhere near
simulating a printer point adjustment is the detector level. Be it PEC or
CCD or whatever.

Unlike film scanning the lab can ONLY adujust the overall light level going
thru the negative, This is not the same as Lift, Gamma or Gain.

Lift has no effect on the final image white level (Neg Min density), Gamma,
in theory has no effect on white or black level and gain has no effect on
final image black level (Neg max density)

I remember the days when the DOP's and film manufacturers request Cintel
designed a device called TKG which gave printer point values relative to
the PEC levels. So long as the PEC values were not adjusted away from
calibration  and a grey scale patch was shot at the head of the scene (lit
correctly for the scene). The TKG automatically located the grey patch and
measured it's RGB values.  It was only designed for rushes/dailies and it
worked quite well. However it soon became clear that the DOPs did not seem
to want to shoot a reference patch for each scene and the concept
dissappeared almost without trace. 
Oh, and it could be set to a lab reference thus calibrating it to the DOPs
favorite Lab norm. 

Look on the back of  URSA, C-Reality, and I think DSX,, and you will see
three BNCs marked TKG. These are were analog feeds from the PEC amps. The
clever bit was that as the measurement was before the color channel, a full
Lift, Gamm & Gain grade could be performed without upsetting the TKG

Ah those were the days.

Peter winson
Peter Swinson Associates Limited   

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