The limit to brightness
 

In article ,
Mortimer wrote:
It's more noticeable on documentaries such as house makeover or
house-hunting where they are probably using low-budget (and physically
smaller) cameras to keep production costs down and make the cameras less
intrusive,

More likely a camera lent to the subject to film 'out of hours'

but I've also seen it on some dramas with high production values
(properly graded pictures, etc).

You can't simply shoot with natural contrast ratios. The 'system' simply
can't cope with it. You either have to light the foreground to reduce the
contrast, or reduce the brightest parts with filters of some sort - or a
mixture of both. Modern cameras can also 'bend' the gamma to reduce the
level of highlights. But even with all this some crushing will be accepted
under some conditions.

It's the same sort of thing as happens with audio. If you have a drama
with some whispering and shouting, you have to alter both those levels to
something acceptable for domestic viewing. Not only because the average
domestic set couldn't produce that dynamic range.

--
*Black holes are where God divided by zero *

Dave Plowman London SW
To e-mail, change noise into sound.

The limit to brightness
 

"Andy Wade" wrote in message
...
On 31/08/2012 09:41, The Other Mike wrote:

Is that the case? A few years back there was some key sequence to use on
BBC
digital text on Freeview to get a test card on the screen.

The MHEG test card is still available on the DTT platform: go to LCN105
(BBC red button channel) and press yellow as soon as the MHEG welcome page
appears. Then go to any other channel, and back to 105. This time press
green at the welcome page and you should see a 'status page'. Press green
for the test card and a rendering of TCW will appear after a short delay.

As noted here before though, this test card isn't terribly useful for
setting up displays. I find, with a CRT display, that for pictures to
look right the TC has to to be set with the blacks somewhat crushed.


Thanks.
Colours etc ok for me on mine.
All borders and squares ok but surprised the middle circle is slightly
squashed.
Regards
David

The limit to brightness
 

In article , R. Kennedy McEwen
wrote:

Gamma 2.2 significantly over-corrects and results in shadows having
limited perceptual resolution. The gamma used by the Mac is closer to
the human eye's response.

The human eye response is only one factor which determines the ideal
gamma, and the 1.8 gamma of the Mac is no better, given the other
factors, than 2.2.

The official PAL spec is 2.8, though as most CRTs are nearer 2.2, that's
what most broadcast cameras are lined up to, or they were when I worked
with them. BBC test chart 57 gives a linear staircase display on a
waveform monitor when gamma is 2.2 near black and 2.5 near white. The
Nikon 990 still camera I once tested on this chart also gave equal
brightness steps, indicating that they use the same gamma values as
television. I have no idea why they chose 1.8 for the Mac, unless it was
just to be different.

Rod.
--

The limit to brightness
 

In article , Paul Ratcliffe wrote:
Contrast is another issue, though. Cheap LCD TVs still seem to suffer
from glowing blacks, greatly reducing the apparent contrast ratio.

But the manufacturers tell you they've got a million to one contrast
ratio on their screens, so you must be wrong and it's your eyes that
are at fault.

The contrast you will see on a screen is not only dependent on the
properties of the screen, but the ambient light falling on it. The darkest
tone any screen can reproduce is the colour of the screen itself when it is
switched off, and under most conditions that isn't anywhere near black.

Or they could just be making it up as they go along.

Now there's a possibility.

Rod.
--

The limit to brightness
 

In article en.co.uk,
Roderick Stewart wrote:

I have no idea why they chose 1.8 for the Mac

Because, back in the mid 80s, it was considered to match printed
output better. Now that serious work is done using colour profiles
for each device, it makes more sense to use a gamma that more closely
matches the display hardware, and recent versions of MacOS X use 2.2
by default.

-- Richard

The limit to brightness
 

Roderick Stewart wrote:

The contrast you will see on a screen is not only dependent on the
properties of the screen, but the ambient light falling on it. The darkest
tone any screen can reproduce is the colour of the screen itself when it is
switched off, and under most conditions that isn't anywhere near black.

Quite !!

At least contemporary screens are a lot 'blacker' than they used to be.

http://www.theexpgroup.com/blog/wp-content/uploads/2010/07/ExP_old_TV1.jpg

The limit to brightness
 

Dave Plowman (News) wrote:

You can't simply shoot with natural contrast ratios. The 'system' simply
can't cope with it. You either have to light the foreground to reduce the
contrast, or reduce the brightest parts with filters of some sort

What sort of filter reduces contract?

Bill

The limit to brightness
 

On Fri, 31 Aug 2012 09:41:05 +0100, The Other Mike
wrote:

On Thu, 30 Aug 2012 21:27:42 +0100, Graham Murray
wrote:

Maybe that is the reason that the TV stations no longer broadcast the
testcard - so that people will not discover that it is impossible to
correctly adjust the set so that the greyscale bars correctly progress
from black to white with a contrast between each section.

Is that the case? A few years back there was some key sequence to use on BBC
digital text on Freeview to get a test card on the screen.

There still is. I have Test Card W showing at the moment:

1) Tune to BBCi on 105
2) When BBCi background appears press Yellow, within 30 seconds
3) Tune to another channel
4) Go back to 105
5) When BBCi background appears press Green, within 30 seconds
6) Wait between 30 seconds and a couple of minutes and TCW should
appear.

This is a simpler sequence than it was 4 years ago when we were told how
to do it in this ng by Roderick Stewart


--
Peter Duncanson
(in uk.tech.digital-tv)

The limit to brightness
 

Dave Plowman (News) wrote:

You can't simply shoot with natural contrast ratios. The 'system' simply
can't cope with it. You

That's interesting - I don't know any of this stuff.

So basically, then, it means there is too much dynamic range in a "real
life" scene for the cameras and the rest of the broadcast chain? Hence
using fill lighting to bring up the shadows. Have I understood
correctly?

I'm glad we got this discussion going - I love learning new stuff. :-)

--
SteveT

The limit to brightness
 

Mark Carver wrote:

At least contemporary screens are a lot 'blacker' than they used to be.

Yes, absolutely, and it's well worth remembering. My Sony LCD is very
dark indeed when it's switched off, but I remember some older CRTs had
a very light screen - like an insipid pale brownish colour. No way
could that produce realistic blacks.

--
SteveT