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Setting brightness with 0% stimulus?

post #1 of 13
7/24/12 at 5:31am
Thread Starter 
If video black is 16, why not just measure Y on a 0% field/window and raise brightness until Y actually increases? Wouldn't the first sign of luminance be the point where you would want to set brightness? Flashing patterns have always been very subjective to me, so I always try to look for data to back it up. Let me know if I'm in left field on this.
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post #2 of 13
7/24/12 at 6:55am
I good idea in theory. Unfortunately, it almost impossible for any meter to spit out identical readings twice in a row at near-black levels, so there would be no way to tell if the different reading is due to raising brightness control or just meter variation (or display fluctuation) ... and then there's the speed issue....
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post #3 of 13
7/24/12 at 9:53am
Was just playing around with this with a C6 at our offices.

It actually works well assuming you've got a meter capable of measuring that low.

But as HDTV mentioned, speed is a bit of an issue, and once you get the hang of using a pluge pattern, it's very fast to set with a pluge.
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post #4 of 13
7/24/12 at 9:57am
You MIGHT be able to find a meter for circa $3500 or so that could read current black levels on most displays and projectors... maybe. It wouldn't be cheap no matter how you go about it. You'd also have to have a reference black room to do the measurement in because darker TVs and projectors are so dark that the light from a single LED anywhere in the room would affect your measurement of "black".

FAR easier, faster, and cheaper to have a 0% and 2% PLUGE pattern or digital 16, 17, 18, 19, etc. pattern (having below black would be helpful but not completely necessary).

The are called light meters because they are good at measuring light and not good at measuring dark.
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post #5 of 13
7/24/12 at 10:30am
Quote:
Originally Posted by sotti View Post

But as HDTV mentioned, speed is a bit of an issue,

LOL ... especially if you're using HCFR with a D2 and "average many (dark) readings" enabled. smile.gif I'd hate to see how long it takes an i1 Pro in the same circumstances. I'm assuming your C6's are quite a bit faster ...
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post #6 of 13
7/24/12 at 10:42am
Thread Starter 
Quote:
Originally Posted by sotti View Post

Was just playing around with this with a C6 at our offices.
It actually works well assuming you've got a meter capable of measuring that low.
But as HDTV mentioned, speed is a bit of an issue, and once you get the hang of using a pluge pattern, it's very fast to set with a pluge.

Which pluge pattern do you use and what's your usual method?
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post #7 of 13
7/24/12 at 10:44am
Quote:
Originally Posted by Doug Blackburn View Post

You MIGHT be able to find a meter for circa $3500 or so that could read current black levels on most displays and projectors... maybe. It wouldn't be cheap no matter how you go about it. You'd also have to have a reference black room to do the measurement in because darker TVs and projectors are so dark that the light from a single LED anywhere in the room would affect your measurement of "black".
FAR easier, faster, and cheaper to have a 0% and 2% PLUGE pattern or digital 16, 17, 18, 19, etc. pattern (having below black would be helpful but not completely necessary).
The are called light meters because they are good at measuring light and not good at measuring dark.

I think something like a C6 would fare quite well, especially if the display in question only had an average or poor black level. Have you had the opportunity to test out a meter from D3 family (C6, D3 PRO, OEM i1Display, etc.)?

CNET uses the following metric for MLL:

Good: +/- less than 0.009
Average: +/- 0.009 to 0.019
Poor: +/- 0.02 or higher

(all in fL, with 40 fL peak white targeted)
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post #8 of 13
7/24/12 at 10:54am
Quote:
Originally Posted by HDTVChallenged View Post

I'm assuming your C6's are quite a bit faster ...

Yes, but only if the number of samples per reading are kept at 5 or less (10 and 20 really slow things down at 0%). The C6 also has adaptive exposure, which automatically optimizes the exposure time based on the luminance level being measured (Y reading dependent).
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post #9 of 13
7/24/12 at 10:55am
Quote:
Originally Posted by duke32 View Post

Which pluge pattern do you use and what's your usual method?

the best pattern I've found is the black clipping pattern on the AVS disc
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post #10 of 13
7/24/12 at 11:53am
Thread Starter 
Quote:
Originally Posted by PlasmaPZ80U View Post

the best pattern I've found is the black clipping pattern on the AVS disc

I've used that pattern before, but there's people that say 17 should flash or 19 should flash. Then you have the other camp that says those type of patterns are wrong all together.

I'm using a D3 PRO and when I measure a 0% window, I get no fluctuation until the point where luminance kicks in.
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post #11 of 13
7/24/12 at 12:14pm
I found that on a sharp elite which has great black level I could see the difference between correct, one click down and one click up with a C6 and the right pattern ramp.
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post #12 of 13
7/24/12 at 12:45pm
Quote:
Originally Posted by duke32 View Post

I've used that pattern before, but there's people that say 17 should flash or 19 should flash. Then you have the other camp that says those type of patterns are wrong all together.
I'm using a D3 PRO and when I measure a 0% window, I get no fluctuation until the point where luminance kicks in.

I also like the AVS pattern, it's not so much that 17 or 19 should flash, but that 16 should disappear.

We are setting black, so the only value to really be concerned about is level 16. The trick about pluge patterns is what the display is doing, is it like plasma or CRT where the black level can float a little depending on content? Does it have local dimming or one of the new tricks some of the LED LCDs have introduced? Those variables are what effect the usability of a pattern.
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post #13 of 13
7/25/12 at 10:07am
I think the bottom line is that even with the most cantankerous Plasma or CRT, you can set black-level using a pluge a/o clipping pattern in the time it takes to perform one (accurate) meter reading.

Now, finding the ideal balance between black-level and low-range "gamma" response is a related issue that probably does require a meter to sort out.
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