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post #6691 of 6702 Unread 07-31-2015, 03:12 PM
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Quote:
Originally Posted by Kid Jansen View Post
Wouldn't the accuracy of measurements on a TV with a QDEF (Quantum Dot Enhancement Film) depend on its color gamut? There are TV's with a QDEF that are only aiming for DCI-P3 color space, of which only the monochromatic 615 nm red would be difficult to measure. But there are also TV's with a QDEF that are aiming for the much larger Rec. 2020 color space. I know that Nanosys / 3M demonstrated 93.7% Rec. 2020 coverage with QDEF at the last SID Display Week and I know from a direct source at Nanosys that with better color filters from DNP that were also demonstrated at SID Display Week they expect to reach 96 to 97% coverage of the Rec. 2020 color space.

I think that the i1D3 would have quite some difficulty measuring that accurately and I highly doubt the deviations would be smaller than 3 dE2000, especially with the red primary.
Perhaps, but I see very little evidence of this from the SUHD. In the Movie mode--which is essentially Rec. 709--the red primary reference measurement is x0.637, y0.332 and the i1D3 measurement was off from that by only 0.3 dE. When I switched to Natural Mode--which essentially a DCi-P3 mode--the red reference measurement was x0.675, y0.312 and the i1D3 dE was now 0.8. This is a larger error to be sure, but still one that is negligible. In fact, the i1D3 has the least trouble with red and blue regardless of the gamut. The errors in green and white are larger.

To be very specific our Quantum Dot mode is intended for use with the Samsung SUHD displays, which are currently by far the most popular quantum dot displays available. If other manufacturers release QD TVs that capture a meaningful market share then we will look at providing support for that as well.
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post #6692 of 6702 Unread 07-31-2015, 07:30 PM
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Yes. When setting up an auto-cal session, you specify gamma. BT.1886 is one of the choices.
Guess I forgot to add my TV brand, its an ST60 plasma, I don't have an auto-calibrate option. Is there any other way to do it manually?
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post #6693 of 6702 Unread 07-31-2015, 08:45 PM
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Guess I forgot to add my TV brand, its an ST60 plasma, I don't have an auto-calibrate option. Is there any other way to do it manually?
Sure, just select BT.1886 in the gamma module and adjust to the indicated targets. Make sure that you include the black and white levels in Options, Calibration, BT.1886.

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post #6694 of 6702 Unread 07-31-2015, 09:07 PM
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Originally Posted by TomHuffman View Post
Sure, just select BT.1886 in the gamma module and adjust to the indicated targets. Make sure that you include the black and white levels in Options, Calibration, BT.1886.
Thanks, I see it now. The white/black levels, they are defaulted to 120/0.03, do they have to be set to something specific or is that like a standard?
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post #6695 of 6702 Unread 08-01-2015, 02:01 AM
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Without putting words into people's mouths who actually know, yes... You have to manually measure your 100% and 0% and update the values.
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post #6696 of 6702 Unread 08-01-2015, 05:16 PM
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Without putting words into people's mouths who actually know, yes... You have to manually measure your 100% and 0% and update the values.
So I take it you do a 0% and 100% reading, input the values into chromapure and go from there? It seems like it's a little more involved than a straight 2.2 calibration, what if your meter doesn't do a 0% reading very well? I have a hard enough time getting my meter to get a good reading under 20%, much less 0%.

Its an i1 display pro meter btw, for reference.
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post #6697 of 6702 Unread 08-01-2015, 05:17 PM
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Originally Posted by dunan View Post
So I take it you do a 0% and 100% reading, input the values into chromapure and go from there? It seems like it's a little more involved than a straight 2.2 calibration, what if your meter doesn't do a 0% reading very well? I have a hard enough time getting my meter to get a good reading under 20%, much less 0%.

Its an i1 display pro meter btw, for reference.
If you can't measure black, then just use the defaults. BT.1886 IS "more involved" than using a straight power law gamma like 2.2. You have to measure black and white levels first.

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post #6698 of 6702 Unread 08-01-2015, 05:24 PM
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Originally Posted by TomHuffman View Post
If you can't measure black, then just use the defaults. BT.1886 IS "more involved" than using a straight power law gamma like 2.2. You have to measure black and white levels first.
Ok, Is that the only difference then, just the B/W measurements first?
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post #6699 of 6702 Unread 08-01-2015, 06:36 PM
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Quote:
Originally Posted by dunan View Post
Ok, Is that the only difference then, just the B/W measurements first?
Yes, but you also need to have a display that allows gamma adjustments at 5% or (as a minimum) 10% increments. If you don't have gamma adjustments at those intervals, BUT do have white balance at those intervals then, at each point, first adjust Green to hit the target luminance, then tweak Red & Blue to restore white balance (you might have to tweak Green slightly).

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post #6700 of 6702 Unread 08-01-2015, 07:44 PM
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Originally Posted by davehancock View Post
Yes, but you also need to have a display that allows gamma adjustments at 5% or (as a minimum) 10% increments. If you don't have gamma adjustments at those intervals, BUT do have white balance at those intervals then, at each point, first adjust Green to hit the target luminance, then tweak Red & Blue to restore white balance (you might have to tweak Green slightly).
OK good, my ST60 has a 10 point gamma adjustment, but wont be as good a calibration as with a 5 point I'm assuming

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post #6701 of 6702 Unread Yesterday, 03:10 PM
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Quote:
Originally Posted by dunan View Post
Ok, Is that the only difference then, just the B/W measurements first?
The biggest difference is that the BT.1886 gamma curve is based on your device's dynamic range, that is why you measure black and white first. If your device has a (near) infinite dynamic range, like OLED, then there is no difference between BT.1886 and a fixed 2.4 gamma. If your TV only has a 1000:1 contrast though, then the curve will start with 1.25 at 17 and ends with 2.26 at 234 (8 bit studio swing signal levels are 16-235, but white and black don't have a gamma value). Especially for devices with a narrow dynamic range you'll see very low gamma values near black with BT.1886.

The reason for this is that on a device with a limited dynamic range you'd crush the blacks with a fixed value gamma curve. If for example we'd take a TV with a 5000:1 contrast, then signal levels 16-20 would all show as black if it strictly followed a fixed 2.2 gamma curve, because:

((20-16) / 219)^2.2 < 1/5000

The part between the brackets converts a studio swing signal value to a decimal value so it can be gamma encoded.

For gamma 2.2 signal levels 16 and 17 are displayed identical at a 141,000:1 contrast, so to eliminate black crush altogether you'd need a contrast ratio that's significantly higher than that. At gamma 2.4 that 141k already becomes 414k and at gamma 2.6 it's already at 1.22M. So as said before you'd need a (near) infinite dynamic range to strictly follow a fixed value gamma curve. With BT.1886 on the other hand, the gamma curve is tailored to your device's dynamic range, which results in much better gradation in the darker shades.

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post #6702 of 6702 Unread Today, 07:04 AM
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^^Nice post

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