About
When HDR is enabled, almost all SDR content in Windows looks wrong and washed out, even it's own UI. dwm_eotf_rs solves this problem by replacing Desktop Window Manager's piecewise sRGB transfer function with proper gamma curve.
It does that by reading memory of the loaded dwmcore.dll module, patching shaders that are responsible for incorrect SDR to HDR conversions and writing it back.
This is an alternative implementation of the same idea that is behind dwm_eotf. dwm_eotf_rs is a major upgrade in terms of QoL, it also provides additional features, such as system tray controls, Multi-Plane Overlay toggle, autostart and shader dumping. It's more reliable as well, as it does not require multiple retries for it to work and it's brightness scaling feature is less buggy.
You do not need to disable/revert the patch (or restart DWM) when playing HDR games or videos. It only affects DWM composed SDR content!
Usage
Help Output
Patches DWM's shaders to use proper EOTF (gamma)
Usage: dwm_eotf_rs.exe [OPTIONS] [GAMMA] [COMMAND]
Commands:
dump Dumps DWM's original shaders as DXBC
restore Restores original sRGB EOTF and enables Multi-Plane Overlay
schedule Creates a task ('dwm_eotf_rs') that runs the app on user logon
unschedule Removes the startup task from Task Scheduler
help Print this message or the help of the given subcommand(s)
Arguments:
[GAMMA] Exponent to use during EOTF patching [default: 2.2]
Options:
-c, --compatibility-mode Patch DWM and exit (disables tray mode)
-m, --mpo-state Optional Multi-Plane Overlay toggle (set to false to prevent some apps from bypassing DWM) [possible values: true, false]
-n, --nits Optional target SDR brightness in nits (depends on display setup, see ReadMe)
-i, --ignore-whitelist Patch every shader that contains sRGB EOTF or alpha correction patterns
-s, --skip-patching Prevent automatic patching on app start (tray mode only)
-w, --wait-time Delay (in seconds) before patching on start (tray mode only) [default: 5]
--brightness Optional brightness multiplier (legacy dwm_eotf compatible factor)
--no-alpha-fix Disable alpha correction fix when increasing brightness (see ReadMe)
-h, --help Print help
-V, --version Print version
Tray Mode
By default, the app runs in system tray, where you can toggle patch as needed as well as select a gamma value (2.0/2.2/2.4/[GAMMA]).
When it launches, it will wait a few seconds (specified by -w option) before inital patching to avoid problems in some edge cases.
Compatibility Mode
When supplied with the -c flag, dwm_eotf_rs works like a simple console app - it patches DWM and exits.
Startup
The app can register itself to run automatically when user logs in, using the Windows Task Scheduler (task named dwm_eotf_rs).
The -c schedule argument combination schedules dwm_eotf_rs to autostart in Compatibility Mode. This is the intended way to use the app.
In tray mode, the context menu includes an "Autostart" checkable item that toggles the startup task on or off. If the gamma value is changed while autostart is on, the task is updated to use the new gamma.
Brightness Control
It's possible to set a desired paper white brightness in nits using the -n option. dwm_eotf_rs takes the highest SDR content brightness value of all your displays (as set in Windows Settings) and calculates the scaling factor for EOTF. The program additionally patches "AlphaCorrectSDR", "BoostSDRLuminance" and similar shaders to fix UI transparancy issues introduced by brightness scaling.
The --brightness option allows to set a brightness multiplier directly, but uses the math compatible with original dwm_eotf and might not be interpreted in terms of nits.
Multi-Plane Overlay
Some apps and most games use the Multi-Plane Overlay (MPO) GPU feature to render their UI directly (so called "Independent Flip"), bypassing DWM and it's shaders (patched or otherwise). Most Electron and NW.js apps (e.g. VS Code, RPGM), Unity games, Chromium-based browsers and a lot of others use MPO.
dwm_eotf_rs will disable/enable MPO via registry when -m false/-m true is provided. There is also a relevant toggle in Tray Mode.
Do note that some apps and games will force Independent Flip if it's fullscreen anyway (when nothing obscures the app's window, to be more precise). Disabling MPO might also reduce performance of games.
Whitelist
By default, dwm_eotf_rs will patch a predefined set of shaders (and an extra set when using --nits/--brightness without --no-alpha-fix). It should cover most use cases, but it's possible to patch all shaders with same patterns with an -i flag.
Shader Dumping
The app can dump DWM's shaders as DXBC files for research purposes.
These shaders are nested. There are 30 top-level shaders and hundreds inside. Use --big-shaders flag to dump only former.
Library
dwm_eotf_rs depends on shader_patcher library from this repository that can be used to implement patching of other apps.
Known Issues
- Chromium, NW.js and Electron-based apps (Web browsers, VS Code, RPGM games, etc) also use incorrect curves and will switch back and forth between original and fixed look sometimes.
- Setting
--force-color-profile option (same as #force-color-profile in browser flags) to hdr10 or scrgb-linear will remove flicker, but the app will use it's own HDR implementation.
- Alternatively, set that flag to
srgb and disable MPO (see section on Multi-Plane Overlay above). This will fix flicker and allow dwm_eotf_rs to work at the cost of HDR.
- As mentioned above, some SDR games bypass DWM when in fullscreen regardless of MPO settings, so the
dwm_eotf_rs will not help. You can use ReShade with Lilium's "SDR TRC Fix" shader in such cases.
Acknowledgements
- Many thanks to ledoge for original C implementation.
