[Tig] More memories please

[Richard Jackson]

Neal's right: if "programmable" means "controllable by an external  
computer" then no. (Remember that the Altair PC is circa 1975 - the  
same time period as this product!).

    The interesting feature of the CBS Labs Color Corrector is that  
it had an "Automatic" mode: it would look for whites and blacks in  
the video and automatically null out any chroma it found there. The  
target market was broadcasters who (at the time) still used a lot of  
film sources on-air: from commercials to news stories (film at  
eleven!) to feature shows. Depending on the age, processing, and a  
bunch of stuff you guys know more about than I, films could take on  
an overall tint - green, blue, whatever. Broadcasters didn't have  
time to rebalance the film chain for each new film, so the CBS Color  
Corrector was supposed to automatically null out any overall "tint"  
it found.

    The main challenge was its dependence on accurate video levels.  
It knew that "white" (100 IRE) video should be chroma-less, and  
"black" video (7.5 IRE) should be chroma-less, but that it shouldn't  
try to null out chroma on in-between video levels for fear of  
removing a correct color. If the incoming video levels weren't  
accurate, the automatic portion of the Color Corrector would make the  
wrong decisions. The "Semi Automatic" mode was a sample and hold: the  
operator could sample a known black frame, and then a known white  
frame, and the unit would hold those correction values and not try to  
dynamically change with the program material.

    - Richard Jackson
      (ex-CBS Labs)



On Dec 17, 2007, at 4:36 PM, Kassner, Neal wrote:

>
> Rob wrote:
>
>> There was also a CBS/Thomson color corrector in the 70s, I
>> don't recall if it was programmable, but was quite useful at the  
>> time.
>
> I still have a remote control panel from a Thomson-CSF Labs color
> corrector. If it's the one you're thinking of, no, it wasn't
> programmable. It had R/B/G (note the order) black/white paint knobs  
> and
> R/B gamma knobs. There are a couple of toggle switches, too, marked
> COLOR: Colorimetry/Balance, MODE: Manual/Auto/Semi, CORRECTION:
> Off/Operate/Bypass, and a SAMPLE pushbutton with two indicator lights,
> one for white and one for black.
>
>
> Neal Kassner
> Colorist
> CBS News/NY
>
> njk at cbsnews.com
>