Quote:
Originally Posted by wa2ise
If there's an area of the picture with a constant color (in a scene, like sky) one could infer a burst. It would have to be done by hand to adjust the tint at least for every scene. Adjust until you get the faces right. Labor intensive.
Another complication for NTSC is if the CRT display in the kinescope has some horizontal nonlinearity. Which would look like a gradual shift in tint if you demodulated the photographed chroma subcarrier. But one could model such nonlinearity in the decoder program if there's say a title screen of some constant color at the beginning or end of the show. PAL is more tolerant of such phase errors, as the phasing flips from line to line. SECAM material should be immune to this, SECAM may be the easiest to recover the color here. Oh, no burst to tell U from V, but just shift the line alternation of the decoder if the colors come out weird.
Of course this is dependent on someone running the kinescope capture process not bothering to filter out the chroma subcarrier. Probably using equipment built before color TV was installed elsewhere in the station. "Oh, we'll just low pass filter the film to video converter later.".
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Well, the bigger issue with NTSC kinescopes of color programs is that by and large, they are not made the same way that UK telerecordings were: which is to say from a MONOCHROME monitor source that displayed (with sufficient resolution) the fine patterning of the accidentally-included color portion of the transmission signal. It is that patterning that allows Mr. Russell's process to recreate and decode the color portion of the PAL signal.
Unfortunately, here in the US, most B&W kinescopes of color programs were shot off of COLOR monitors that had shadow masks-- which, (along with NTSC's inherently lower resolution) effectively killed any patterning due to the resultant dot-crawl artifacts and softness of the image.
-Kevin