¶ Special K HDR Retrofit in 6 Brutal Steps
A. Display must support HDR
B. Windows Desktop must be in HDR Mode
C. HDR Retrofit only works in D3D11, D3D12, and OpenGL (and possibly D3D9 games…)
D. HDR Retrofit only works for Patrons
Step 1. Launch a D3D11, D3D12, or OpenGL game (or possibly a D3D9 game…)
Step 2. Configure the game to run borderless fullscreen for max. compatibility.
Step 3. Display Special K’s control panel menu (Ctrl + ⇧ Shift + ← Backspace)
Step 4. Open the HDR menu at the top of Special K’s control panel menu and press the HDR Setup button.
Step 5. Select the scRGB HDR option from the HDR Calibration widget.
Step 6. Restart the game.
¶ HDR Calibration Guide
Special K v 0.11.1 has made significant changes to its HDR processing, and while we think it is 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That info is out of date, and you’re better off ignoring it.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.
¶ 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 increase the dynamic range, but decreases contrast |
| 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 |
| [Reset] | Resets the currently selected HDR Preset to the software default + Said default often changes between releases |
¶ Tonemap Modes
These control luminance response when processing HDR
¶ Passthrough
- No tonemap is applied; luminance scales linearly from SDR to target luminance
- No control over color saturation or mid-tone contrast is possible
- Tends to over-saturate and over-brighten, but … some people really like that
¶ 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
¶ 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
¶ Pipeline Remastering
Pipeline remastering is a feature of Special K’s HDR retrofit that increases the range and precision of intermediate render passes to infuse/preserve HDR qualities early in the render pipeline rather than try to produce an HDR image using a game’s final output alone (i.e. Xbox Auto-HDR).
Remastered passes include things like atmospheric scattering, HDR (pre-tonemap) light accumulation, and (unfortunately) shadow maps and FMVs. Not all passes work as intended when their range and precision are increased, and the performance cost of upgrading these render passes varies from game to game.
Special K v 0.11.1 has disabled all of the render pass remastering options by default, since they were the source of many compatibility issues.
However, remastering is important for image quality and, in some games, even required for the UI.
You are encouraged to enable these yourself, they just cannot be the default policy or support requests from first-time users would never end 
¶ Cost Analysis of Remastering (v 0.11.1)
Special K v 0.11.1 adds new statistics to the Remastering Tooltips:
1) VRAM Allocation Statistics for Remastered Render Passes
2) Ratio of Passes Eligible for Remastering vs. Actually Remastered
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
Remastering does have a performance impact, but it is difficult to measure.
The underlying SDR -> HDR process without remastering has virtually no performance overhead.
¶ HDR Visualizations
¶ Luminance
¶ vs. EDID-Max-Avg-Y (Maximum Full Field Luminance)
This visualizes image brightness versus the maximum luminance your display can process across the entire screen.
It is acceptable to exceed the range of this visualization, but ideally you would limit the pixels too bright for Max-Avg-Y to less than half the screen.
¶ vs. EDID-Max-Local-Y (Maximum 10% Window Luminance)
This visualizes image brightness versus the maximum luminance your display can process in a 10% local window. This is your display’s ability to handle HDR highlights, and it can only guarantee this level of performance in small localized regions. Obeying this limit is important or atmospheric bloom will inevitably wash out image detail that existed in the original SDR image!
Any solid color produced by either of the EDID visualization modes is a luminance level your display is capable of displaying without using smoke and mirrors. What you need to watch out for are color cycling pixels, they are out-of-range for your display and you must dial-back luminance settings or you will lose image detail.
Color cycling pixels are too bright for your display; they will not be clipped (unless in HGIG mode), but will cause the image to be processed differently.
¶ 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 <path-to-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
¶ Global Default INI Settings
¶ Default INI that will Enable HDR in all Games Automatically
(how good an idea this is, is up for debate)
[Render.DXGI]
UseFlipDiscard=true
[Render.OSD]
;HDRLuminance: 1.0 = 80 cd/m^2, 9.375 = 750 cd/m^2
HDRLuminance=9.375
[SpecialK.HDR]
scRGBLuminance_[0]=18.75
scRGBGamma_[0]=1.0
ToneMapper_[0]=1
Saturation_[0]=1.0
MiddleGray_[0]=1.25
Use16BitSwapChain=true
AllowFullLuminance=true
Preset=0
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:
-
Press and Hold: Ctrl + Shift while starting the game
-
Press [Reset Config]
¶ HDR Retrofit for DirectX 9 games
¶ Disable native HDR in games without an in-game toggle
Special K v21.03.20 added support for hiding HDR support from games so they do not enable HDR. This is of particular interest for titles with no in-game HDR toggle present, and can allow the full use of Special K’s HDR retrofit in those titles which may result in a better HDR experience in comparison.
- Install Special K for the game, either globally or locally.
- Launch and close the game once to allow the Special K config file to be created.
- Open the game-specific config.
- Find and change the parameter
HideHDRSupportto true. - Save and close the file.