[Gllug] Two Questions

[Chris Bell]

On Thu 10 Feb, Nix wrote:
> 
> On Wed, 9 Feb 2005, Chris Bell yowled:
> >                  Computer monitors are generally sold by size rather than
> > quality, so who cares about things like gamma, colour integrity, and
> > phosphor persistence as long as it is cheap?
> 
> They *are* in a vicious price spiral right now: my latest monitor is of
> slightly lower quality than the one I bought seven years ago, but has
> 50% or so more screen area and cost less than a fifth as much.
> 
> >                                              Who bothers to fit expensive
> > long persistence colour matching room lighting?
> 
> You can use CRTs with direct artificial lighting turned on? *shudder*
> 
   We used special grade 1 colour monitors with specified phosphors,
monochrome monitors with tinted filters in front, and low intensity lighting
from "Colour Matching" or "Northlight" (Colour matching without the near-UV
frequencies) tubes fitted with adjustable shields so that the light was
aimed straight down and away from the screens. We had hand-held reference
colour light sources, calibrated exposure meters, and special test signals
to help, and then a single monitor was used to determine the final colour
balance so that everything should be matched, even if slightly incorrect. We
could also switch colour on/off at the monitor to help identify slight
colour drift.
   The only problems then were associated with making all pictures taken
from all directions under all lighting conditions at all times of the day,
were correctly exposed and matched, regardless of the way the cameras were
moved around and shots changed. It is still a difficult job; try looking at
a field from different directions close to sunrise or sunset with all the
vegetation blown in one direction, so we used to compare the pictures with
some recorded earlier and argue amongst ourselves about what was best.

-- 
Chris Bell

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