Author Topic: Heads up - dimming issue for HDR videos  (Read 3433 times)

Offline desray

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Re: Heads up - dimming issue for HDR videos
« Reply #30 on: April 20, 2019, 18:53 »
The Sony OLED is really good. But given a choice, I’d still go for the LGs C8 or C9, it has tone mapping feature that the Sony A8F doesn’t have. Tone mapping is a very important feature that I would not wanna miss out having.

A lot of the Tekno3d files that you are watching now are specially tone mapped at source, which is why u r seeing a lot of details. This tone mapped feature when kicks in, will emulate the dynamic metadata so content will look like Dolby vision... without the tone mapping feature, HDR10 will all pass through using the static metadata and it will not utilise the built in TVs algorithm for dynamic HDR . A dynamic HDR is much better than a static HDR

Important to have this tone mapping feature, the JVC N7 PJ has this feature

Yes, tone-mapping feature is a boon feature to have. Then confirm Sony A8F don't have liao as I can't find the HDR settings that deals with tone-mapping. So Tekno3D mkv files already tone-mapped at the source end? So literally omitted the need for LG C7 to perform tone-mapping am I right?

And what is this techicolor HDR mode that you mentioned? What does it correspond to? any baseline? like DCI-P3 or BT2020?

Offline desray

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Re: Heads up - dimming issue for HDR videos
« Reply #31 on: April 20, 2019, 19:13 »
These are some pre-calibration measurements for HDR on the Technicolor mode. Just the basic ones, didn't measure the color accuracy yet for primary and secondary colors.

Green, Cyan and Red seems to be a bit off in the Gamut....






What is technicolor HDR mode? Is it using BT2020 chromaticity? Anyway since this is pre-calibration, this is only telling you what the technicolor entails in terms of the White balance, the color gamut and the luminance level (brightness). Colors have 3D - there are defined as HSL - (Hue, Saturation and Lightness).

If purely based on this pre-calibrated results, the BT2020 is barely hitting 70% (which is within the acceptable range for BT2020 - anything below 70% just shows the limitation of the color gamut unable to reach a good color reproduction of HDR). That's not a good mode to start with for calibration. I'm pretty sure after calibration, it will improve.

For the primary colors, the green is too much as far as White balance point is concerned. Green affects the overall luminance levels which directly ties to your brightness level, thereby affecting the contrast indirectly. Rule of thumb for calibration, green should not be touched unless absolutely necessary...play with Red and Blue gains/bias to compensate for the green.

For secondary colors, the Yellow, Cyan and Magenta (CMY), there is a huge color shift especially on the Yellow which affects the skin tones of a human.

In terms of chromaticity (colors), the green is under-saturated and so is Cyan. This will make the greenery a little more yellowish.

But these are just pre-calibration figures of what Technicolor HDR mode entails...I have no clue what are we measuring the base against.

Offline sevenz

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Re: Heads up - dimming issue for HDR videos
« Reply #32 on: April 20, 2019, 21:39 »
I need to see the LG C7 before I can make any comments...who knows, LG may be even better than the Sony A8Fin certain areas...I'll never know until I actually spend some time looking at the HDR and SDR content of what C7 can produce before I pass any kind of judgement. It will be unfair.

Cool understand. :)

Well if u don't mind my noob experience in display, and it's convenient for u, I invite u or any bros to look at the C7 calibrated PQ. :)

SDR is fully calibrated, 21 point, for 2 modes - bright and dark room. recently did fine tuning to reduce the deltas.

For HDR, it's a 2pt calibration for greyscale only. CMS is untouched as advised by the US calibrators.

Offline sevenz

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Re: Heads up - dimming issue for HDR videos
« Reply #33 on: April 20, 2019, 21:40 »
Anytime bro, just pm me. Can arrange. 😁

T u so much :) pmed!

Offline desray

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Re: Heads up - dimming issue for HDR videos
« Reply #34 on: April 20, 2019, 22:21 »
Cool understand. :)

Well if u don't mind my noob experience in display, and it's convenient for u, I invite u or any bros to look at the C7 calibrated PQ. :)

SDR is fully calibrated, 21 point, for 2 modes - bright and dark room. recently did fine tuning to reduce the deltas.

For HDR, it's a 2pt calibration for greyscale only. CMS is untouched as advised by the US calibrators.

What's your address?

Offline sevenz

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Re: Heads up - dimming issue for HDR videos
« Reply #35 on: April 20, 2019, 22:30 »

Offline sevenz

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Re: Heads up - dimming issue for HDR videos
« Reply #36 on: April 20, 2019, 23:49 »
Additional good info on the ABL vs dimming on LG 2017 OLEDs. See time stamp 4:50 in Vincent's review:
https://www.youtube.com/watch?v=F9OvPfPd8s0

Similar dimming issue on Samsung TVs too. This video captures it quite well.
https://www.youtube.com/watch?v=qwb6VEDUWAI
« Last Edit: April 21, 2019, 00:05 by sevenz »

Offline sevenz

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Re: Heads up - dimming issue for HDR videos
« Reply #37 on: April 21, 2019, 00:46 »
These are some pre-calibration measurements for HDR on the Technicolor mode. Just the basic ones, didn't measure the color accuracy yet for primary and secondary colors.

Green, Cyan and Red seems to be a bit off in the Gamut....





Just to add on. The coverage of the wide color gamuts seems quite consistent with RTINGS. See here:
https://www.rtings.com/tv/reviews/lg/c7-oled

Offline ronildoq

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Re: Heads up - dimming issue for HDR videos
« Reply #38 on: April 21, 2019, 08:41 »
Bro, I found the solution to your dimming lights issues

SWITCH OFF DYNAMIC CONTRAST on the OLED , when the tv kicks in into HDR mode, go in expert settings and turn off dynamic contrast.

So when desray mentions that it increased the blacks, it makes sense that the only setting that improved the black levels are dynamic contrast. Switch that off and turn on subtitles now, u will not see the dimming issue now

Voila !

Offline ronildoq

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Re: Heads up - dimming issue for HDR videos
« Reply #39 on: April 21, 2019, 09:49 »
Forgot to mention that on LG C7, setting the dynamic contrast to Low will turn on the tone mapping feature for HDR10 and it will use the TVs algorithm for tone mapping.

Even if the source file is specially tone mapped, the TV will still use its algorithm to process and tone map the HDR10 pic  if this is turned on, this includes the Tekno3d files

Superb quality when dynamic contrast is turned on for HDR10, but subtitles u will have the dimming issue

Hope that helps bro

Offline ronildoq

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Re: Heads up - dimming issue for HDR videos
« Reply #40 on: April 21, 2019, 10:56 »



Here is the manual, that’s what it does and why u r seeing dimming when subtitles appear ...

The answer to your question is in the manual

Either u switch off subs or switch off dynamic contrast .


Sent from my iPhone using Tapatalk

Offline desray

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Re: Heads up - dimming issue for HDR videos
« Reply #41 on: April 21, 2019, 13:11 »
Good find Ron...thanks for sharing with the rest.

Offline sevenz

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Re: Heads up - dimming issue for HDR videos
« Reply #42 on: April 21, 2019, 13:48 »
Forgot to mention that on LG C7, setting the dynamic contrast to Low will turn on the tone mapping feature for HDR10 and it will use the TVs algorithm for tone mapping.

Even if the source file is specially tone mapped, the TV will still use its algorithm to process and tone map the HDR10 pic  if this is turned on, this includes the Tekno3d files

Superb quality when dynamic contrast is turned on for HDR10, but subtitles u will have the dimming issue

Hope that helps bro

Thanks for this bro. Good point.

Yes, 'Dynamic Contrast LOW' is meant to activate the dynamic tone mapping or Active HDR function on the OLED, a feature in the LG that helps enhance the HDR PQ using dynamic metadata on top of the static metadata. And if i'm not wrong, it's to help in the darker scenes too

Let's see if I understood this correctly....

So does this mean, if we disable dynamic tone mapping, it will just rely on whatever tone mapping that is done on the source (e.g. by Tekno) and ONLY static metadata, and then output it as it is?

And if we enable dynamic tone mapping, besides the tone mapping done by the source (e.g by Teckno), there will be one additional layer of tone mapping by the display that adds dynamic metadata? ie. it will then have whatever metadata that is intended by Tekno, and additionally dynamic metadata
« Last Edit: April 21, 2019, 13:55 by sevenz »

Offline desray

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Re: Heads up - dimming issue for HDR videos
« Reply #43 on: April 21, 2019, 14:24 »
Thanks for this bro. Good point.

Yes, 'Dynamic Contrast LOW' is meant to activate the dynamic tone mapping or Active HDR function on the OLED, a feature in the LG that helps enhance the HDR PQ using dynamic metadata on top of the static metadata. And if i'm not wrong, it's to help in the darker scenes too

Let's see if I understood this correctly....

So does this mean, if we disable dynamic tone mapping, it will just rely on whatever tone mapping that is done on the source (e.g. by Tekno) and ONLY static metadata, and then output it as it is?

And if we enable dynamic tone mapping, besides the tone mapping done by the source (e.g by Teckno), there will be one additional layer of tone mapping by the display that adds dynamic metadata? ie. it will then have whatever metadata that is intended by Tekno, and additionally dynamic metadata


Sounds about right...

Offline ronildoq

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Re: Heads up - dimming issue for HDR videos
« Reply #44 on: April 21, 2019, 14:29 »
Thanks for this bro. Good point.

Yes, 'Dynamic Contrast LOW' is meant to activate the dynamic tone mapping or Active HDR function on the OLED, a feature in the LG that helps enhance the HDR PQ using dynamic metadata on top of the static metadata. And if i'm not wrong, it's to help in the darker scenes too

Let's see if I understood this correctly....

So does this mean, if we disable dynamic tone mapping, it will just rely on whatever tone mapping that is done on the source (e.g. by Tekno) and ONLY static metadata, and then output it as it is?

And if we enable dynamic tone mapping, besides the tone mapping done by the source (e.g by Teckno), there will be one additional layer of tone mapping by the display that adds dynamic metadata? ie. it will then have whatever metadata that is intended by Tekno, and additionally dynamic metadata

Spot on ! That’s correct !!

 

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