On Monday, 1 January 2018 21:17:39 UTC, charles wrote:
multipliers reduce EHT stability. They also, by introducing RC type time de
lays, reduce the effectiveness of the usual practice in valve sets of letti
ng B+ voltages waver all over the place, designing the set so everything co
mpensates and the picture doesn't shift.
I sometimes experience lemon tinted whites when watching B&W
films on a modern TV, say when a character is wearing a
white shirt - while all the other whites show up ok. Also sometimes
the sky has a distinct lemon or mauve tinge.
There's a way around it by altering the settings although offhand
I can't remember what it is. ISTR it may also be affected by the
Another variable throw into the mix: not all black and white films on TV are
the same shade. The film base may develop a slight colour tint as it ages,
which leads to greys that may be very pale mauve or very pale green. You'd
think that when B&W films were transmitted on TV, they would set R=G=B so as
to achieve pure, untinted B&W irrespective of the colour of the original
They used to be something called a colour killer that locked the telly
to monochrome when a monochrome prog was on. When it didn't work the
picture would have spurious colours, usually flashing. It was most annoying.
I realise that broadcasters used to turn off the colour carrier when a
monochrome programme was broadcast, though I imagine towards the end of
analogue TV, broadcast equipment might start to protest if the CSC was ever
For digital, I'm surprised that the source material direct from the telecine
doesn't have the three components set to equal values, long before it gets
as far as the broadcast equipment.
Talking Pictures TV shows a lot of B&W material and there is often a colour
cast - most noticeable when they change from one film to a trailer for
another at an advert break.
All down to costs. Everyone knows digital is perfect so can be used with
no human intervention to check things.
If 'they' can't get something like audio levels somewhere near close when
doing a transfer, not much hope for far more complicated pictures.
*If at first you don't succeed, try management *
Dave Plowman email@example.com London SW
It will be, in the same way that analogue scanners and cameras
However, to produce the monochrome part of the picture, the
three signals have to be combined in exactly the correct ratio
which is 59% Green, 30% Red and 11% Blue.
TV signals were produced in digital form for years before DSO
so the analogue signals produced from them needed to be in
exactly the same proportions to avoid upsetting the colour
That's a totally different effect: the eye sees colours (they are a negative
of the correct colours) and the eye/brain tires of seeing those colours so
when a black and white image is seen, the colour sensitivity of the eye
varies for different parts of the image so the eye sees a hint of the
The one that TW demonstrated used strobing or patterning to tire some of the
cones more than others in the eye, so as to achieve that same goal of
varying colour sensitivity of the eye.
Others have talked about the psychological experiments with B&W TV but
it crosses my mind that there could be lots of reasons why a solid-state
colour TV has difficulty interpreting black, white and only greyscale in
between, ranging from the set, the method of transmission and even down
to the transfer from celluloid to digital in the first place.
Going back even further, the original B&W film stock may not have been
true black on a clear-as-water celluloid base and different chemical
processes can give different results. Guess who was given a copy of "The
Book of Alternative Photographic Processes (Third Edition)" for Christmas?
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