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post #1 of 12 Old 04-14-2017, 04:10 PM - Thread Starter
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Calibrating HDR10 on LG OLED

Hey all,

Finally decided to calibrate my LG OLED C6 for HDR10 playback using the CalMAN workflow and Masciola's patterns on an USB stick. Not going to jump into UHD/HDR too much, but my Xbox One S is finally connected to an HDR capable receiver and a few games I have support HDR (like Mass Effect Andromeda), so figured I should at least get the settings in line.

From my understanding, pretty much the only thing I can/should measure and change, using the HDR Standard picture mode, is the the Brightness, OLED Light, Contrast, Color (Tint) and the Gamma adjustments. Correct?

Also, is the ST 2084 HDR (PQ) Gamma curve the only curve one should use for HDR10 calibration or can the traditional power values (such as 2.2, 2.3, 2.4, etc) be used? I'm a little confused by the EOTF curve graph in place of the traditional Gamma curve graph for CalMAN...

Thanks!
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post #2 of 12 Old 04-15-2017, 02:16 AM
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Originally Posted by BigCoolJesus View Post
Hey all,

Finally decided to calibrate my LG OLED C6 for HDR10 playback using the CalMAN workflow and Masciola's patterns on an USB stick. Not going to jump into UHD/HDR too much, but my Xbox One S is finally connected to an HDR capable receiver and a few games I have support HDR (like Mass Effect Andromeda), so figured I should at least get the settings in line.

From my understanding, pretty much the only thing I can/should measure and change, using the HDR Standard picture mode, is the the Brightness, OLED Light, Contrast, Color (Tint) and the Gamma adjustments. Correct?

Also, is the ST 2084 HDR (PQ) Gamma curve the only curve one should use for HDR10 calibration or can the traditional power values (such as 2.2, 2.3, 2.4, etc) be used? I'm a little confused by the EOTF curve graph in place of the traditional Gamma curve graph for CalMAN...

Thanks!
Hi, Contrast/Brightness settings in HDR are not working like we know in SDR, Brightness should left untouched, because the display gamut/tone mapping is based to these default settings.

HDR is using ST.2084 which is an absolute curve, the display has to follow specific luminance levels per digital level, according to the Dolby's golden reference numbers, so you are following to up to the luminance levels the display is capable and you clipp or roll-off (hard/soft)...(it's up to each display internal gamut/tone mapping programming)...the higher from display's peak output levels the display can't follow.

So when you have a 650nits capable display you see about up to 70.5% of the signal, the other info will be clipped or roll-off (hard/soft), it's up to each display internal gamut/tone mapping programming.

Other examples:

75.2% is 1000 nits
90.2% is 4014 nits
97.7% is 8047 nits
100% is 10000 nits

The PQ curve charts have different curve shape from the familiar ones of SDR calibration because 100% is 10.000 nits.

If you reduce Contrast/OLED from LG, you will reduce the peak output, OLED/Contrast @ 100 provides better color tracking at these default values.

In SDR we use Gamma curve as transfer function (where you can set it to 2.2/2.4/BT1886 or whatever value you like....having in calculation the display Black/Peak White level to generate each digital level luminance levels, but in HDR the PQ Curve transfer function has fixed numbers from 0-10.000nits, you follow or you clip, you can't modify or use other values.

Ignore CMS adjustments and do RGB Balance adjustments only.

Each of the White Balance control in HDR has a specific +- value working range which not introduce problems to real content. The range of values are different from point-to-point. At low end controls the adjustments has to be very minimal. Play some different content and play with each control until you find up to which values you don't see problems. Use different movies/scenes to have plenty of different palettes to evaluate.

Using LG instructions for HDR calibration it will increase your color errors and provide lower peak output but better Grayscale and gamma tracking, but the color errors are more important from grayscale errors in that case.

After some testing performed using a 65E6 @ HDR mode, lowering the OLED Light, can improve the Grayscale but increase the color errors. To compare what is happening you have to take 5-Point Saturations (or 10-Point)

If you keep the Contrast/OLED @ 100, and calibrated the RGB levels for HDR, then you get an average Grayscale of about 1.6dE2000 and the errors are coming from gamma (brigher) at mid range while the RGB balance is near perfect....you get about 670nits calibrated.

If you run a 5-Point Saturation with targets DCI P3 inside a REC2020 (look CalMAN HDR workflow) then you get about ~2.0dE2000 average.

If you keep the Contrast @ 100 and reduce OLED about 80? (I don't remember the exact value...to get 540nits) and calibrated the RGB levels for HDR, then you get an average Grayscale of about ~1.0dE2000 (or lower)and the errors of gamma are reduced at mid range while the RGB balance is near perfect....you get about 540nits calibrated.

If you run a 5-Point Saturation with targets DCI P3 inside a REC2020 (look CalMAN HDR workflow) then you get about ~4.0dE2000 average.
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post #3 of 12 Old 04-15-2017, 04:38 AM - Thread Starter
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THANK YOU!

Excellent response. Covers everything I need to know.

Sent from my Nexus 6P using Tapatalk
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post #4 of 12 Old 04-15-2017, 06:12 AM - Thread Starter
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Quote:
Originally Posted by ConnecTEDDD View Post
HDR is using ST.2084 which is an absolute curve, the display has to follow specific luminance levels per digital level, according to the Dolby's golden reference numbers, so you are following to up to the luminance levels the display is capable and you clipp or roll-off (hard/soft)...(it's up to each display internal gamut/tone mapping programming)...the higher from display's peak output levels the display can't follow.

So when you have a 650nits capable display you see about up to 70.5% of the signal, the other info will be clipped or roll-off (hard/soft), it's up to each display internal gamut/tone mapping programming.
Ted,

So for ST.2084 Gamma using the CalMAN workflow, when I make adjustments, the goal is simply to try and get RGB tracking near 0 for all values without introducing real world content issues (the lower end adjustments are the most sensitive to change) and the EOTF curve will fall into line accordingly?

I ask because as you know, for SDR, one might use both the Gamma curve and the RGB tracking to tailor their results. But it sounds like for HDR, the only goal is to get RGB tracking in line and wherever the curve falls is where it falls without really being able to change it (since the curve corresponds to the displays overall nit ability).

Thanks!

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post #5 of 12 Old 04-15-2017, 11:09 AM
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Originally Posted by BigCoolJesus View Post
Ted,

So for ST.2084 Gamma using the CalMAN workflow, when I make adjustments, the goal is simply to try and get RGB tracking near 0 for all values without introducing real world content issues (the lower end adjustments are the most sensitive to change) and the EOTF curve will fall into line accordingly?

I ask because as you know, for SDR, one might use both the Gamma curve and the RGB tracking to tailor their results. But it sounds like for HDR, the only goal is to get RGB tracking in line and wherever the curve falls is where it falls without really being able to change it (since the curve corresponds to the displays overall nit ability).

Thanks!
Fixing only RGB Balance errors will require less control adjustments, to these displays calibration is more like art than science (as D-Nice said), this means that you have to sacrifice high adjustments (so leave errors) to be able to get watchable picture. dE Charts don't tell the whole story, controls are not aligh with patterns also, you have to test some stuff and them watch some movies scenes to confirm that there no added problems to shades/distortions/pixel-blocking etc..

Tracking of PQ transfer function is not possible because it will require high adjustments which will introduce serious problems to real content.

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post #6 of 12 Old 04-15-2017, 11:17 AM
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A nice thing to do is keep watching a greyramp while balancing rgb,its easy to get it look like a rainbow : )
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post #7 of 12 Old 04-15-2017, 11:56 AM - Thread Starter
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Thanks for the input!

Looks like for HDR, baby steps is the name of the game (small adjustments, watch, small adjustments, watch)
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post #8 of 12 Old 04-18-2017, 06:42 AM
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Hi all!

Self-calibrating HDR on an LG OLED and would like to join the discussion and ask for opinions and advices. Any input would be much appreciated!

I'm aware that HDR near black leves have very low luminance (0.00X nits) but starting from what levels (Black(64) - 68 - 73 - 77 - 81 - 86 - 90 - etc. ) you can see bars blinking in the Black Clipping HDR pattern in a dark room with a naked eye after some adaptation period?
All bars are distinguishable from a full black field or some are crushed?


When referring to a real world content what movie scenes (dark, bright, colorful?) and test patterns are you using for tests? (Grayscale ramp, gradient, ...?)
Any 'known issues' to check in the first place?
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post #9 of 12 Old 04-18-2017, 07:27 AM - Thread Starter
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Originally Posted by M-V View Post
Hi all!

Self-calibrating HDR on an LG OLED and would like to join the discussion and ask for opinions and advices. Any input would be much appreciated!

I'm aware that HDR near black leves have very low luminance (0.00X nits) but starting from what levels (Black(64) - 68 - 73 - 77 - 81 - 86 - 90 - etc. ) you can see bars blinking in the Black Clipping HDR pattern in a dark room with a naked eye after some adaptation period?
All bars are distinguishable from a full black field or some are crushed?


When referring to a real world content what movie scenes (dark, bright, colorful?) and test patterns are you using for tests? (Grayscale ramp, gradient, ...?)
Any 'known issues' to check in the first place?
From my recent delving into the topic, I would highly recommend you purchase Masciola's HDR test pattern download (Google Masciola). All you need to do is put his test patterns on a USB stick and plug it into the LG and voila, the patterns kick the LG into HDR mode and you are free to adjust away.

Regarding Black Clipping, using HDR Standard picture mode with default Brightness 50, near black value 73 can be seen flashing from a few inches away and, if you focus really hard and block out the white light from the numbers on the pattern, value 68 can just barely be seen flashing...at least on my display. It is advised to NOT TOUCH the Brightness setting regardless of what the pattern shows on your TV as it throws other HDR values and pre-mapped points out of whack. I have found that what you see with default values is about what you are going to get aside from using a meter to calibrate the grayscale.

Regarding real world content, the Masciola download has five excellent HDR test scenes that will show obvious issues if you change settings too much.

My advice, based on playing around yesterday, is to use HDR Standard with Contrast and OLED at 100, Brightness at 50, other settings left on default (such as Tint and Color), Dynamic Contrast Off, Color Gamut Normal, and all other enhancements turned off as usual.
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post #10 of 12 Old 04-18-2017, 08:52 AM
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Originally Posted by BigCoolJesus View Post
From my recent delving into the topic, I would highly recommend you purchase Masciola's HDR test pattern download (Google Masciola). All you need to do is put his test patterns on a USB stick and plug it into the LG and voila, the patterns kick the LG into HDR mode and you are free to adjust away.

Regarding Black Clipping, using HDR Standard picture mode with default Brightness 50, near black value 73 can be seen flashing from a few inches away and, if you focus really hard and block out the white light from the numbers on the pattern, value 68 can just barely be seen flashing...at least on my display. It is advised to NOT TOUCH the Brightness setting regardless of what the pattern shows on your TV as it throws other HDR values and pre-mapped points out of whack. I have found that what you see with default values is about what you are going to get aside from using a meter to calibrate the grayscale.

Regarding real world content, the Masciola download has five excellent HDR test scenes that will show obvious issues if you change settings too much.

My advice, based on playing around yesterday, is to use HDR Standard with Contrast and OLED at 100, Brightness at 50, other settings left on default (such as Tint and Color), Dynamic Contrast Off, Color Gamut Normal, and all other enhancements turned off as usual.
Thanks for the info!

I'm already using Ryan's patterns and they are doing the job and are great overall.
But when it comes to 'Test footage' and I start looking at this photo (girl in a studio with a color target behind) ->


I personally have a very strong feeling that exactly the same photo in SDR is looking way much better than a HDR version. (More natural skintone, shadow, etc.)
I'm certainly not trying to get full HDR/SDR match but such results are a bit confusing.

With black level -
Whenever I get 68 barely visible 64 is not zero black...
When I try to get WB point (code value 127) luminance around what the standard is saying (PQ 127 = 0,1410 nits, LG doc says code 127 = 0.14 nits)
I can barely (almost invisible) see 72 flashing and ~68-70 are clipped.

So here is another question
What is more important: seeing all near black levels distinctly but loosing zero-black or clipping some of the near black but keeping 0-black and following PQ more accurately on near black levels?

Real picture looks "nicer" and "as if there is more contrast" when some of the near black is clipped.
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post #11 of 12 Old 04-18-2017, 03:27 PM - Thread Starter
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Thanks for the info!

I'm already using Ryan's patterns and they are doing the job and are great overall.
But when it comes to 'Test footage' and I start looking at this photo (girl in a studio with a color target behind) ->

I personally have a very strong feeling that exactly the same photo in SDR is looking way much better than a HDR version. (More natural skintone, shadow, etc.)
I'm certainly not trying to get full HDR/SDR match but such results are a bit confusing.

With black level -
Whenever I get 68 barely visible 64 is not zero black...
When I try to get WB point (code value 127) luminance around what the standard is saying (PQ 127 = 0,1410 nits, LG doc says code 127 = 0.14 nits)
I can barely (almost invisible) see 72 flashing and ~68-70 are clipped.

So here is another question
What is more important: seeing all near black levels distinctly but loosing zero-black or clipping some of the near black but keeping 0-black and following PQ more accurately on near black levels?

Real picture looks "nicer" and "as if there is more contrast" when some of the near black is clipped.
I cannot give an in-depth "professional" reply as I am merely a high level amateur when it comes to understanding calibrating (at least for SDR...HDR is an ongoing lesson for me right now).

But, from what I have gathered so far is two things are fairly certain for HDR on the 2016 LG OLED:
1) Do not adjust the 127 value for WB...leave it alone, forget about it, ignore it
2) You shouldn't touch the Brightness value, either
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post #12 of 12 Old Yesterday, 11:42 PM
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Hi guys,

i am about to "calibrate" my LG E6 for HDR10 as well using Mascior`s patterns and HCFR. Could you please let me know which of his patterns you have used?

And Ted... thanks for your outstanding support once again!

Greetings

Felix
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