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Re: TTEF



5/June/96  Howard wrote:
> In response to Jean-Pierre's note:
> Since each film stock requires a different setup for contrast and 
> color balance, please explain how the TTEF system can be applied and 
> used with many different film stocks, as well as with Fuji film.

Even if it seems too good to believe, the Kodak TTEF system relies upon 
ONE alignment film only; this film carries three plain grey 
patches per frame only. (1)
At Aaton we call it "Film-Trois-Gris" (3-Grey-Film) to avoid metonymic 
confusion between the TTEF "Film" and the TTEF "System", 
and to eliminate the semantic vicinity between TTEF and TAF 
which are so different in their fundamental principles.

Kodak will sell the "3-Grey-Film" -- recorded on 5293/7293 --
with instructions for the colorist to set nine video levels 
(three colors x three densities) with the lift, gamma and gain commands
of his telecine: a straightforward operation with a nine window digital 
voltmeter.(2)
Once these settings are stored, the telecine becomes a photo-
densitometer. Any 18% grey card in the frame will be converted
into "Kodak '93TTEF status" densitometric values. (3)

At this stage the '93TTEF status is still rawstock specific.
For example, an 18% grey card - photographed on the set with the exact
lighting conditions - will deliver video levels convertible into 
R25 G25 B25 Printer Lights if it is recorded on E-K'93 film only. 
That is why, until now, telecines have been adjusted with color reference 
films using the same rawstock the real thing is shot on.

The Kodak engineers' bright idea  -- that transforms the rawstock 
specific 
'93TTEF setup into a "universal" reference --  is that E-K will 
publish the '93TTEF related look-up table of each of its professional 
films.  
These tables will be used worldwide to convert the 3 color signals
of '93TTEF'd telecines into perfectly accurate RGB densities 
(or Printer Lights) for each of their films.  
It is important to use the exact film look-up table and not
an average one, because averaging could induce more than +/-2 Printer 
Light errors over the normal E-K product line, and even more with 
EK-5296 PrimeTime film. (4)

It is right that the error would be high on Fuji films as their 
D-Min and color balance are different from the E-K ones. 
Fuji will probably negotiate the right to publish its own 
look-up tables for its customers to benefit from the 
Kodak '93TTeffed telecines.

------------------------------
(1)  It brings both operational simplicity and cost advantages over
rawstock specific alignment films and charts.

(2)  The system has been tested in three different facilities, 
on both Philips BTS and Rank URSA, with two to four colorists in each 
facility: it took them from 1 to 4 minutes to converge on the 9 targets.

(3)  The 3-Grey-Film itself is transparent to the process. 
It is only the combination of the three grey patches and the nine target 
levels that sets the telecine to the "'93TTEF status". 
When your reference E-K'93 film is worn, you will either receive another 
E-K'93 film with the original nine target values, or a "3-Grey-Film shot 
on another rawstock with a different set of targets: this will change 
nothing to your telecine '93TTEF settings.

(4) Relax! There is no possible confusion: the grey card 
sampler-converter will always enter the right look-up table because 
its keycode reader automatically recognizes which is the rawstock. 
-------------------------------

JPB / Aaton