HDR to SDR Tone Mapping is Incorrect

[Anonymous]

The HDR to SDR conversion done for Windows' "Stream HDR" function is Incorrect. Instead of converting PQ EOTF to sRGB gamma (the default windows SDR transfer function), PQ EOTF is converted to 2.4 gamma, causing a washed-out picture on sRGB calibrated displays. This problem is unable to be fixed on built in displays because most have no ability to change SDR transfer function without complicated workarounds such as applying a 3dlut through Windows DWM. 

[AndrewG_Intel]

Hello @Anonymous

Thank you for posting on the Intel® communities.

In order to review this further, could you please provide us with the following information?

1- Is this a new system? Did the computer work fine before or are you experiencing this behavior since the first day that you have the device?

2- If this worked fine before at any moment, were there any recent hardware or software changes that might relate to the point when the issue started? (for instance, Windows*, driver, software, or BIOS updates?)

3- Since Microsoft's website offers the drivers as a "single bundle package driver", and therefore, we are not able to review driver versions, could you please confirm if the current graphics driver "27.20.100.9621" reported by Intel® SSU is the latest one available from Microsoft*? Also, could you please confirm if the system is running the latest BIOS? (as per the Intel® SSU, it is running BIOS 9.106.140).

4- Just to make sure we understand correctly, is the issue only with the built-in display or also with external displays?

5- When you said "PQ EOTF", are you referring to "perceptual quantizer - electro-optical transfer function"?

6- Please provide a Report for Intel® Graphics Drivers following the steps on the link. If the issue is also on external displays, make sure they are connected to the computer when running the report.

7- Please fill up the Template for submitting a Graphics bug available in the link. Please make sure to provide detailed step-by-step instructions for issue reproduction.

Best regards,

Andrew G.

Intel Customer Support Technician

[Anonymous]

1- Is this a new system? Did the computer work fine before or are you experiencing this behavior since the first day that you have the device?

no, this has been an issue from day 1

2- If this worked fine before at any moment, were there any recent hardware or software changes that might relate to the point when the issue started? (for instance, Windows*, driver, software, or BIOS updates?)

n/a

3- Since Microsoft's website offers the drivers as a "single bundle package driver", and therefore, we are not able to review driver versions, could you please confirm if the current graphics driver "27.20.100.9621" reported by Intel® SSU is the latest one available from Microsoft*? Also, could you please confirm if the system is running the latest BIOS? (as per the Intel® SSU, it is running BIOS 9.106.140).

yes, the current graphics driver is the latest available from microsoft for my surface laptop 3. there is a firmware update history posted by microsoft on their website which contains updates they have pushed to each surface device (drivers and firmware). you can use the tool lessmsi to extract the specific drivers, too. uefi firmware is up to date, microsoft releases all updates (drivers, firmware, etc) for surface devices thru windows update and they are automatically installed.

4- Just to make sure we understand correctly, is the issue only with the built-in display or also with external displays?

the issue affects both external and built-in displays. because i cannot change the gamma on my built-in display, i cannot work around this issue. external displays usually offer the ability to change gamma so it's not really an "issue" in that case, however it is still wrong. the windows default SDR gamma is sRGB and HDR video should be tone mapped to sRGB gamma instead of 2.4 to reflect that.

5- When you said "PQ EOTF", are you referring to "perceptual quantizer - electro-optical transfer function"?

yes, PQ HDR10. the pictures i included were streams from netflix in standard hdr10 format.

6- Please provide a Report for Intel® Graphics Drivers following the steps on the link. If the issue is also on external displays, make sure they are connected to the computer when running the report.

ok

7- Please fill up the Template for submitting a Graphics bug available in the link. Please make sure to provide detailed step-by-step instructions for issue reproduction.

ok

[Anonymous]

Category	Questions	Answers (N/A if not applicable)
Description	Provide a detailed description of the issue	The HDR to SDR conversion done for Windows' "Stream HDR" function and local HDR10 playback on compatible SDR displays with UWP apps is Incorrect (they use the same mechanism for tone-mapping). Instead of tone-mapping PQ EOTF to sRGB gamma (the default windows SDR transfer function), PQ EOTF is tone-mapped to 2.4 gamma, causing a washed-out picture on sRGB calibrated displays. This problem is unable to be mitigated on built in displays because most have no ability to change SDR transfer function without complicated workarounds such as applying a 3dlut through Windows DWM. Still, the problem remains that windows default gamma is sRGB and HDR video is instead being tone-mapped to 2.4 gamma.
Hardware (HW)	Brand and Model of the system.	Microsoft Surface Laptop 3 13.5”
	Make and model of any Displays that are used to see the issue (see note2 below). LFP = Local Flat Panel (Laptop panel)EFP = External Flat Panel (Monitor you plug in)	LFP=Sharp LQ135P1JX51
	Provide any other hardware needed to replicate the issue. ie: Cables&brand, cable type [vga, hdmi, DP, etc], dock, dongles/adapters, etc	n/a
	Hardware Stepping (see note1 below).	Intel64 Family 6 Model 126 Stepping 5
Software (SW)	SW or Apps version used to replicate the issue.	Netflix 6.97.752.0, Movies & TV 10.21092.10731.0
Configurations	Single display, clone, or extended (see note2 below).	Single display
	Display resolution & refresh rate setting of each display (see note2 below).	2256 x 1504 (60p Hz) display is adaptive sync compatible (20p Hz—60p Hz) as well and UWP apps let display match video framerate.
	AC or DC mode, i.e. is power cable plugged in or not?	both
How to repro	Please provide steps to replicate the issue. These steps are very crucial to finding the root cause and fix. A screenshot to illustrate the issue is a huge plus. A video of the failure is even better! Attach to the post or provide the YouTube link.	1. Make sure “Stream HDR content” is enabled if using Netflix 2. Play HDR10 video on built in or external SDR display calibrated to sRGB gamma that does not support HDR formats but does support "Stream HDR video" tone mapping 3. see attached pictures 4. n.

[AndrewG_Intel]

Hello perrinpages

Thank you for your response and for all these details. Please allow us to review this further and we will be posting back in the thread as soon as more information is available or in case more details are required from your environment.

Best regards,

Andrew G.

Intel Customer Support Technician

[Anonymous]

Thank you, hopefully this can be resolved in a timely manner.

[AndrewG_Intel]

Hello perrinpages

We are still working on this matter. However, we understand that the issue is also observed on external displays despite "a workaround is applied", is this correct?

Since we understand that you also tested on external displays, could you please provide us with the maker and exact/full model of the display(s) that you have tested? (you may also share some links as a reference).

Best regards,

Andrew G.

Intel Customer Support Technician

[Anonymous]

"We are still working on this matter. However, we understand that the issue is also observed on external displays despite "a workaround is applied", is this correct?"

Yes, external displays usually have settings to change sdr transfer function (though an integrated display menu or tv settings) so the issue is apparent but can be worked around.

"Since we understand that you also tested on external displays, could you please provide us with the maker and exact/full model of the display(s) that you have tested? (you may also share some links as a reference)."

https://support.lenovo.com/us/en/solutions/pd500392-thinkvision-p27h-20-flat-panel-monitor-overview

The external display must be capable of srgb/bt709/sdr colorspace only (no WCG or hdr certification). with an external display, streaming hdr video may not be supported so you will need local hdr10 content playing in Windows Movies & TV app for it to tone map. The issue mainly affects built in displays because their requirements for streaming hdr video are lower and they do not offer the ability to change sdr transfer function to something other than the windows default sRGB.

https://support.microsoft.com/en-us/windows/stream-hdr-video-on-windows-2e98fc86-5358-d6bc-1e22-d0e416d3c704#WindowsVersion=Windows_11

https://support.microsoft.com/en-us/windows/display-requirements-for-hdr-video-in-windows-192f362e-1245-e14d-3d3f-4b3fc606b80f#ID0EBD=Windows_11

[AndrewG_Intel]

Hello perrinpages

Thank you for your response and for all these details. We will check this information and we will be posting back in the thread when new details are available.

Best regards,

Andrew G.

Intel Customer Support Technician

[Anonymous]

Any update on this? Does it really take weeks to watch a few seconds of hdr netflix?

[AndrewG_Intel]

Hello perrinpages

Thank you for your patience in this matter.

We would like to recommend trying the following and testing the behavior:

1. Go to Intel® Graphics Command Center.
2. Select the Video tab on the left side menu.
3. Look for the Input Range feature.
4. Change it to Limited or Full to test the behavior (it will depend on the display that you are using)

Please let us know the outcome.

Best regards,

Andrew G.

Intel Customer Support Technician

[Anonymous]

That doesn't work. If input range was set incorrectly, the 2.4 gamma lut I applied would not have "fixed" the issue. 

[AndrewG_Intel]

Hello perrinpages

Thank you for your response and for the clarification. We will be posting more details as soon as possible.

Best regards,

Andrew G.

Intel Customer Support Technician

[AndrewG_Intel]

Hello perrinpages

After investigating this further, we would like to inform you that the function used on the "Stream HDR" Windows feature is controlled by Windows, since is it a software function. And the industry default value for gamma is 2.2, and hence, this is the default value used in this Windows feature.

However, it’s worth noting that the viewing conditions where HDR is consumed may vary the optimal gamma value for the best viewing experience. In general, the gamma 2.2 setting is generally best suited for brighter viewing conditions: think office setting with bright overheads and lots of indirect daytime light from exterior windows. In contrast, the gamma 2.4 setting is generally used for darker viewing conditions: think watching Prime Time television at night in a living room. And this is where the issue you have may be originated, the viewing condition.

As mentioned above, the default industry value for gamma is 2.2, and you mentioned that you used some software (DWM LUT) to apply a custom 3DLUT and force the gamma to 2.4, seemingly correcting the issue. This “correction” you perceive may be due to the viewing conditions where you are consuming the content. And you are correct that this is a complicated workaround. However, Windows does feature the option to adjust the gamma value to get the best viewing experience for the user according to the viewing conditions.

The first option is to calibrate the built-in display for HDR content. This process is described in this article*: https://support.microsoft.com/en-us/windows/calibrate-your-built-in-display-for-hdr-content-in-windows-de1c66fa-6cc0-b327-e73a-1bac6bd46bc0#WindowsVersion=Windows_11

The second option is to adjust the gamma and brightness for the whole Windows UI, which is explained in this article*: https://www.hellotech.com/guide/for/how-to-calibrate-monitor-windows-10

Either option allows the user to change the gamma value to get the best viewing experience for their conditions without using any complicated workaround.

Best regards,

Andrew G.

Intel Customer Support Technician

[Anonymous]

1. No, 2.2 gamma is not the "industry standard". sRGB is the industry standard for web content. They are not the same. bt.1886 is the standard transfer function for HD video content per ITU. 

2. HDR10 transfer function correlates to absolute nit values, so it should NOT vary based on viewing conditions. HDR10 video is to be watched in a dark room only. I'm sure ITU knows better than you because they made the standard! Only HDR video with dynamic metadata such as Dolby Vision was designed to accommodate ambient light. 

3. I know the 2.4 gamma lut I applied is correcting the problem because I compared the picture to a true HDR display and a Dolby Vision compatible SDR display. When the 2.4 gamma lut was applied, the streams matched much better. The HDR display I used was an iPhone 12 Pro, which is an excellent (and accurate) HDR display. I have measured this myself with calibration/profiling software. HDTVTest on YouTube also did his own analysis and found it comparable to a Sony BVM-X300 mastering display!

4. The reason I used a 3dlut to change transfer function is because it is the only way to know I am conforming to industry standard transfer functions. Windows' gamma adjustment is much too coarse and does not truly conform to any other standard other than sRGB!

5. "Calibrating" the built-in display for HDR is pointless if the tone mapping being done is wrong in the first place...

6. I have attached pictures that will hopefully educate you on why my reasoning is correct. Keep in mind the camera doesn't have enough dynamic range to fully capture a true HDR display so it looks a bit darker because of the bright lights.

7. Intel maintains an HDR tone-mapping vpp filter in MediaSDK/oneVPL which I assume is what's being used for Windows tone mapping, so yes this does concern Intel!

[AndrewG_Intel]

Hello perrinpages

Thank you for your response and for these details. We are checking this and we will be posting more information as soon as possible.

Best regards,

Andrew G.

Intel Customer Support Technician

[Supercali]

I'm in the same boat.

I have a HDR-capable laptop with a built-in OLED display directly attached to an Intel CPU.

I can't calibrate HDR in any meaningful way because Windows 11 now "decides what's best", so all HDR content looks utterly wrong. Typically, it's horrendously clipped, or the blacks are crushed, or the gamma curve is wrong, or some combination of all three. 

Similarly, the Intel drivers don't give any control of any type. I can't even enable 10-bit in SDR mode, even though the panel supports it!

Last but not least, the additional RTX 3070 mobile GPU could be used to play HDR games, but NO! It's forced to pass through the Intel GPU to get to the built-in screen, but the iGPU doesn't allow the RTX to "see" that the monitor is HDR-capable.

Physically the panel is quite good, but the software is a total letdown. 

There's no controls available at all. Nothing works. Between Intel and Microsoft, someone has not done their job.

[Anonymous]

Hello, have you tried the software dwm_lut? It's available on github. 

https://github.com/ledoge/dwm_lut

The recommended way to use it is to profile your display in HDR and SDR mode (displaycal is free) then apply the separate 3dluts through the dwm_lut. You will need a colorimeter (i1 display pro is recommended) however. I'll link the discussion from the displaycal forum so you can have some more information. It's really tragic Intel and Microsoft can't figure this out. Apple of all companies offers some ability to calibrate and has sensible picture presets in their "XDR" branded display control panels.

https://hub.displaycal.net/forums/topic/i-made-a-tool-for-applying-3d-luts-to-the-windows-desktop/

I also recommend making a separate post as my problem is slightly different than yours, even though they are related (more posts about a topic will tell Intel there's a problem!). There are a limited number of people who even know what HDR is, let alone what accurate HDR looks like. Good Luck!

[AndrewG_Intel]

Hello perrinpages

After reviewing this further, we have the following details to share:

First, the industry-standard gamma IS 2.2, a simple google search for “industry standard display gamma” can confirm it. A lot of discussion about the “best” gamma value can be found online, but most of those discussions conclude that it comes to personal preference. However, it should be noted that the vast majority of HDR content is recorded using this gamma value, and as such, 2.2 is the ubiquitous recommendation of a baseline gamma from where to then calibrate your display to your personal liking.

Secondly, it should be noted that the "gamma correction" and "HDR to SDR" tools included with Windows* are developed and maintained by Microsoft*. And as such, only Microsoft can actually correct any issue with these tools. So, if you are not satisfied with the options included with Windows, you need to contact Microsoft about it, not Intel.

Finally, your laptop (Surface* Laptop 3 13.5) is listed as NOT supporting HDR (the Intel® SSU confirms this). So, it is unrealistic to expect the same quality from this display as from fully HDR-capable displays (like the iPad* and iPhone* you mentioned). The Windows "HDR to SDR" tool is included to help improve the consumption of HDR content on SDR displays, but it cannot be expected that this tool will magically make SDR panels display the same quality as HDR panels.

Having said that, we will proceed to close this thread from our side. Thank you for your understanding.

Best regards,

Andrew G.

Intel Customer Support Technician