New HDR Calibration Procedure (SK 0.11.1 + HGIG)

Special K v 0.11.1 has made significant changes to its HDR processing, and while I think it’s more suitable now than ever to just set the Peak Luminance Slider to max and call it mission accomplished, if you are willing to put in a little bit of work tuning things the picture is much more capable of “popping” than ever.

Where Did The Actual Guide Go?!

That info is out of date, and you’re better off ignoring it. A revised version of this guide will be released before Special K v 0.11.1 is.

Draft Revision to Calibration Guide

Terms and Settings Explained

Control Description
Paper White Controls mid-tone luminance

    +  Parts of the scene dimmer than this receive minor desaturation

Middle-Gray Contrast Adds or subtracts contrast from typical flesh-tone content

    +  Lowering will increases the dynamic range, but decreases contrast
    +  Increasing is likely to wash out any part of a game’s UI that has faces in it

Bypass sRGB Gamma If your game appears absurdly dark, it probably uses sRGB gamma

    @  When Special K encounters an sRGB SwapChain in HDR, it will give you a
          warning directing you to try this setting to ensure brightness is correct.

[Reset] Resets the currently selected HDR Preset to the software default

    +  Said default often changes between releases
    +  Simplest way to ensure accurate calibration if image processing changes

Tonemap Modes

     These control luminance response when processing HDR

  1. Passthrough

  • No tonemap is applied, only luminance gets scaled from SDR source to your target luminance
  • No control over saturation or middle-gray contrast is possible in passthrough
  • Passthrough tends to over-saturate and over-brighten, but … some people really like that
  1. ACES Filmic

  • Applies a modified ACES Filmic tonemap
    • Very slightly dims the scene
    • Also applies a small desaturation
  • To counter-act the dimming and desaturation: tweak middle-gray and saturation
  1. HDR10 Passthrough

  • Use only in games that are native HDR to begin with
  • Intended to analyze HDR quality in games, but has some potential for image adjustment

You may apply a small tweak to a (Native HDR) game’s Paper White level using this

Remastering, remastered

  • Special K v 0.11.1 has disabled all of the render pass remastering options by default, since that was a source of many compatibility issues.

HOWEVER, remastering is important for image quality and, in some games, required for the UI.

0.11.1 adds:

  1. VRAM Allocation Statistics for Remastered Render Passes
  2. Ratio of Passes that Could have been Remastered to those that Were

With these two additions, you know:

    A. How many, if any, render passes each option is responsible for
    B. How much VRAM you are on the hook for by remastering

The only gray area that remains with remasters, is how much performance impact they have.

Remastering -DOES- have a performance impact, but it is difficult to measure. You will have to figure this out on your own, unfortunately. The underlying SDR -> HDR process w/o remastering has virtually no performance overhead.

Tips and Tricks (SK v 0.11.1 Edition)

Special K v 0.11.1 introduces global default INI value support, and that has a lot of potential in HDR.

Have you dialed-in a really good calibration and wish you did not have to do it again, or could use it as a starting point for other games in your library?

       Special K v 0.11.1’s got your back!

To define default HDR values,

  1. Create Documents\My Mods\SpecialK\Global\default_SpecialK.ini
  2. Place select INI tidbits from the game you just configured in default_SpecialK.ini
  3. Profit

If using a local DLL (e.g. dxgi.dll) to inject Special K, the default INI is called default_dxgi.ini


Default INI that will Enable HDR in all Games Automatically:

      (how good an idea this is, is up for debate)


;HDRLuminance: 1.0 = 80 cd/m^2, 9.375 = 750 cd/m^2


That works for any other aspect of Special K configuration as well, so if you wanted SK’s framerate limiter everywhere, that is how you would do it.

Applying Default Values to a Game Already Played:

  1. Press and Hold: Ctrl + Shift while starting the game

  2. Press [Reset Config]

Gold at the End of the Text

Special K v 0.11.1 (Release Candidate):

64-Bit: SpecialK64.7z (7.6 MB)
32-Bit: SpecialK32.7z (6.3 MB)


Since 0.11.1 is not yet released… here are copies of the latest test build :slight_smile:

SpecialK64.7z (7.6 MB) SpecialK32.7z (6.3 MB)


What about in game brightness ? Is it still recommended to lower it to 25 % or is that not necessary anymore if we just follow the steps ahead ?

I have no suggestions for that at the moment, I’ll revisit the issue over the weekend.

In the meantime, I pulled some new color gamut features out of my hat :slight_smile: It was becoming increasingly difficult to explain the saturation slider or why it’s even there, so now Special K can do this:

And we can clearly see that color saturation is affected by each and every one of those other settings. Most users will be getting some degree of Rec 2020 color in the highlights. Internally SK does its rendering in ACEScg color space, which is wider than Rec 2020. So that’s where that extra color is sneaking in from :slight_smile:

The DCI-P3 and Rec 2020 color levels are generally subdued enough not to be a problem. Have I mentioned I dislike wide color gamuts? I genuinely hate them and cringe whenever I see content saturated that much.

Anyway, new HDR visualization toys:

SpecialK64.7z (7.6 MB) SpecialK32.7z (6.3 MB)


I have looked into this, and it should no longer be necessary.

The middle-gray adjustment is done in log-space, meaning it can add/subtract a tremendous amount of range (relatively speaking, this is no Xbox Series X AI-trained system) without requiring the game’s tone response to change.

I am happy with the general controls available now and their placement in the widget. I think best results generally come from leaving a game in its neutral configuration and focusing entirely on SK’s tuning.

Great. Thanks :+1:t2:

What is HGIG supposed to do here? From what I understood, it doesn’t do anything unless a game has explicit support for it.

When I enable HGIG under HDR Game mode on my LG B9, there is no difference whatsoever.

That’s true, most games don’t know the first thing about the display device they’re attached to, and so HGIG doesn’t work for them. That’s not the case with SK.

HGIG turns off tonemapping and clips anything that’s out of range. This is the behavior you want with SK, since I’m already tonemapping the image to the capabilities of your display and any additional display-side processing will just make things worse.

Right, but am I supposed to notice a difference when enabling HGIG with SK HDR?

I was testing it in AC Black Flag and couldn’t tell.

The main push for HGIG is on consoles where you can set the max screen brightness within the OS level and the game can read that value and tonemap accordingly which will result in an unclipped and well tone-mapped image.

Compare that to what we have today where currently the display is applying a 1k or 4k roll off to fit all of the high brightness data within a 0-800nit range (of LG OLEDS) and then the game is applying another tone-mapped curve when you adjust the HDR brightness on a game by game basis.

It’s just another level of tone-mapping that isn’t needed and cant result in less pop when a 10k nit sun is being mapped to 1k by OS and then mapped again to 800 by TV firmware.

As for if you should be able to notice a difference, I have a C9 and it’s night and day different when looking at extremely bright elements of games, RE2 opening for example the headlights have this slight grey look when you compare it back and forth to HGIG even if the game doesn’t support it (as I am just clipping instead of rolling off)

I prefer the look of HGIG in games, films not so much.

consoles where you can set the max screen brightness within the OS level and the game can read that value and tonemap accordingly

Almost no games support this on either platform.

Why would you use HGIG in an unsupported game with its native HDR? That makes no sense to me.

And again, I was asking about noticing a difference when using SK HDR, can’t see a difference even when starting at the sun in Black Flag.

Isn’t like the point of HGIG that it ends or disabling any other additional tone mapping that the display might otherwise perform, and reproduces the image signal as intended by the game developers as much as possible?

If that’s the case then it doesn’t really matter if there’s a difference if not — best case scenario there’s a (positive) difference. Worst case scenario there’s no difference at all.

As long as the game supports it (which from the sounds of it SK does) then it should be kept enabled regardless of whether there’s a direct noticeable difference or not?

I answered that if you had read my entire message. SK is made with HGIG in mind. Just set the max brightness to over a high value and compare to see what is being clipped / what isnt.

Hey there so I just found this utility though DFs auto hdr video. Found this thread about config and I’m unsure if I have a HGIG display, how would I find that out? It’s a Samsung q80r if anyone happens to know.

As of May 2020, the only TVs that have implemented the HGIG tonemapping mode are the LG 9 and X OLED TVs

Just tested it with the first Division. I’ve got no words to describe how utterly insane it looks…

Had to use some weird values to get it right, but it’s perfect now, no black crush nor overly bright. It looks better than real HDR in 90% of games I’ve played, including some Sony exclusives known for good implementations.

Yeah they use Fair Fight but I never had problems with SpecialK although I also never ventured too far into the Dark Zone areas which are more sensitive.

Can imagine the games usage of snow and very bright lighting and darkness working really well with high dynamic range support, might work well with the simulated lights option off or how it was called again.

Technically something of a optimization but it removes many of the fake lights added which some players prefer though it might be too dark in some situations without these and as it was added some patches in the game uses it more as a optimization toggling off certain additional sources of lighting.

The setting is Neutral Lighting, it’s a must have.

I’d use HGIG everywhere because how a TV’s processing responds to an image outside of its image processing range is undefined. They’ll resort to some kind of unknown eye adaptation algorithm any time a pixel is brighter than its tonemap wants to deal with, and that’s awful for games.

It’s great for movies and streaming content, just pick an image processing preset that looks nice and assume most of the content is going to be needing re-tonemapping. It’s not so great for games that might spend 98% of their time within range and that 2% of time during scene transitions really screwing things up.

This is why the HGIG whitepaper (or whatever) uses a tunnel in a racing game as its example, it’s anybody’s guess how a TV is going to deal with that, even though the graphics engine has an exact behavior in mind.

You mean using it across all HDR games? I was finally able to see the difference/improvement when trying SK HDR in Dark Souls 3.