gnome-saturation-extension

A GNOME extension that let's you change the saturation (and hue) of the whole screen. Requires GNOME 45 or later.

Important limitations

It's not possible to adjust saturation and hue the same way gnome-gamma-tool adjusts gamma, therefore this extension uses a different method (a GLSL effect), but that method has its limitations.

• the adjustment affects screenshots and screencasts
• screenshots and screencasts in practice won't even work properly, see this bug report
• HDR is most likely not supported (I can't test it due to lack of a HDR monitor)
• per-monitor settings only affect logical monitors and only if they're not mirrored, up to 4 monitors are supported
• it needs to be updated for each new GNOME version

Manual installation

git clone https://github.com/zb3/gnome-saturation-extension saturation-extension@zb3.me
cd gnome-saturation-extension
mkdir -p ~/.local/share/gnome-shell/extensions
cp -r saturation-extension@zb3.me ~/.local/share/gnome-shell/extensions

Then you need to log out (GNOME requires this), and once you log back in, you can use gnome-extensions-app to enable and tweak it, or you can do it manually:

gnome-extensions enable saturation-extension@zb3.me

and to open the preferences window:

gnome-extensions prefs saturation-extension@zb3.me

Hacking/Testing

After changing XML settings schema files, we need to rebuild the gschemas.compiled file:

glib-compile-schemas schemas/

To test changes without needing to log in and log out, we can run a nested gnome-shell instance:

dbus-run-session -- gnome-shell --nested --wayland

(then you need enable the extension inside that nested shell)

However, it's important to note that in practice, the GLSL code might run using the older gles2 backend which uses GLSL 1.0 ES shaders that are more limited. To ensure these users don't get a blank screen after enabling the extension, we need to test this extension using that specific backend:

dbus-run-session -- env CLUTTER_DRIVER=gles2 gnome-shell --nested --wayland

For GNOME 49, you need --devkit instead of --nested --wayland.

Run this to pack the extension into a zip file:

zip -r saturation-extension@zb3.me.shell-extension.zip LICENSE schemas metadata.json *.js