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This topic comprises 4 pages: 1 2 3 4
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Author
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Topic: LG brand & Plasma or LC
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Paul Mayer
Oh get out of it Melvin, before it pulls you under!
Posts: 3836
From: Albuquerque, NM
Registered: Feb 2000
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posted 02-28-2009 10:07 PM
Something else Mark stated above needs correcting:
quote:
Now don't forget that at least NTSC is not capable of absolute black anyway. Its black level begins at 7.5 IRE or 7.5% above 0 where 0 would be absolute black!
Wrong. Even though the US version of NTSC uses setup to put picture black at 7.5 IRE, the match monitors are set for light cutoff while displaying 7.5 IRE. That way when the signal level is at 7.5 IRE the monitor is displaying true black. That's the SMPTE standard that is used in all high-end production - 7.5 IRE = cutoff. And cutoff is judged in a totally blacked-out room too - no ambient light in the room (some of the west coast video guys I worked with went so far as to black out all the equipment pilot lights and match-switcher button lights to ensure that the match room was as dark as possible).
Over the years I've seen a few guys try to set up monitors so that they displayed a visible raster when displaying 7.5 IRE, but that is not the standard used in high-quality network-level production.
At my home monitor black level becomes an issue when I need to look at Japanese NTSC, which is often. In Japan, NTSC picture black occurs at 0 IRE - they do not use setup. When displaying Japanese NTSC on a monitor calibrated to the US standard, the blacks become too dark and end up looking crushed. The solution is to raise the monitor brightness level so that light cutoff occurs when displaying 0 IRE instead of 7.5 IRE.
These days, I watch mostly Japanese-produced material, so I tend to leave the monitors set for cutoff at 0 IRE, and settle for raised black levels when watching US-produced stuff. Of course if I need to view pictures critically, I'll reset the monitor black levels accordingly.
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Mark Ogden
Jedi Master Film Handler
Posts: 943
From: Little Falls, N.J.
Registered: Jun 99
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posted 03-01-2009 02:59 PM
quote: Mark Gulbrandsen
I've always wondered why it is that we also did not use true 0 IRE for black level? Doing so doesn't cause any transmission related problems nor can signal processing chains not handle true 0 level....
oooooh ooooh ooooh wait a minute wait a minute . . . I know this one . . .
searching memory . . . searching memory . . .
So in NTSC, the DC level was established by a clamping circuit, and the reference for the circuit was that the DC sync pulse level was always at a fixed distance (40 ire) from the blanking signal. So the idea was that if black level was at 0 ire, then there was a chance that there could be a low-level video excursion beneath blanking and into sync, which would cause the clamping circuit to lose reference and collapse the image. So the so-called pedestal level was set at 7.5 ire to give the video some breathing room and avoid that happening.
At least that's how I remember it. How does NTSC-J get away with it? Beats me.
*******
Claude, or anyone else thinking of buying an LCD set: a piece of advice I always give people in your situation. When you are at your local electronics dealer, and you have in mind a set you want to buy, always ask for the remote control. Punch the "menu" and "video settings" buttons, and see what adjustments you can make manually. Try to find a set that will allow you to vary the intensity of the backlight, and make at least some colorimetry adjustments, RGB gain/bias and the like. I've found that by changing the level of the backlight and playing with the picture and brightness controls, you can arrive at a much more pleasing contrast level. On my Sony XBR5 LCD, which I only LOVE, I brought the backlight intensity way down and the contrast up a ways, and got a picture that was, to my eye, much more viewable then the one it had out of the box. Additionaly, being able to establish custom color settings (which not all sets do) will add to your pleasure over the long haul.
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Mark Ogden
Jedi Master Film Handler
Posts: 943
From: Little Falls, N.J.
Registered: Jun 99
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posted 03-03-2009 09:58 PM
quote: Mark Gulbrandsen
there are also other signals in that sync area too... VITS among them.
Naw, that's not really true. VITS, or VIR, whatever you want to call it, is outside of sync. Remember that vertical sync ends with an equalizing pulse on line 9. Anything after that is technically fair game for modulation, it's just that it's traditionally blanked until line 21. VITS is on line 19. Time code usually starts on line 12.
Look, I was still swimming in my father's balls when all this rubbish got decided. I'm not defending it, and I'm happy it's going. But that's just the way it worked. Hell, if the company I work for had it's way back then, your TV would have had a motor and a big spinning disc in it. Probably would have looked better, too.
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