Re: OT:colors [was:Re: layers]

Pre-digital movie film masters are now stored as sets of three black-and-white
negatives as Dave describes, or as digital images on DVD once that became
available.  Color images are unstable, as the dyes are chemicals with bonds
that break eventually, degrading the image.  The worst problem is, the three
images do not degrade at the same rate.  The separation negatives, however,
use silver deposition on the film which is more stable than the film itself,
which also eventually will degrade through chemical decomposition.

The color-separation negatives can be used in succession through filters,
provided they are in "registration," meaning that reference points on the
image exacly match, and reproduce the original colors if the intensity of the
three images is also perfectly matched.

Recapturing--"Digitally remastering" of old color movies, such as the *Wizard
of Oz," which had advanced deterioration, was accomplished by separating the
three images by filtration into their three component images (digitally, even
though this can also be done on film), rebalancing the intensities, then
recombining in color information in a database, or recording on a DVD.  The
process is extremely tedious if there are scratches, missing patches and so
on, which have to be filled in from adjacent frames and sometimes repaired
with airbrush in graphic arts form, then rephotographed frame by frame.

There's a lot of this sort of thing going on if the economic gain is expected
to cover the cost.

You had it right, Dave.

Neil Mogensen  z 7 western NC mountains

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