Tuning the Linux font rendering stack for a more visually pleasing output.

Includes tweaks for FreeType, fontconfig, and other components. See Overall with Details for more information, and Notes for the list of after-install recommendations and known issues with their possible mitigations.

Visual comparison is available on the project's wiki page.

Note that this project is just a collection of tweaks that reflect the author's vision on how font rendering should look like.

Due to the nature of the rendering stack features used in this project being still experimental or even completely not supported by most of the Linux desktop environments (like proper gamma correction and blending), correct rendering cannot be guaranteed in some cases.

Previously known as freetype-envision

• Improves visibility of the medium and small-sized fonts.
• Adjusts the font environment to support new experimental features of the font rendering stack.
• Keeps the system components and font list intact. No additions or removals, only rendering tweaks.

Download the latest release from the releases page (Assets - Source code) and unpack it.

Open the terminal in the unpacked directory and execute the command below with elevated permissions:

sudo ./lucidglyph.sh install

See User mode for per-user installation.

Then reboot to apply the changes.

Use the same script from the section above with elevated permissions:

sudo ./lucidglyph.sh remove

Then reboot to apply the changes.

Follow the steps from the Install section above and the script will request user confirmation to allow the upgrade.

Warning

Experimental feature, expect things not to work as intended. User feedback is greatly appreciated.

Caution

If you are a power user who relies heavily on symbolic links for custom Fontconfig rules and use lucidglyph versions from 0.10.0 to 0.11.1, please check this to avoid possible corruption of symlinks during an upgrade or removal of this project in per-user mode.

This issue has been resolved and mitigated in 0.12.0 release. No manual intervention is required.

User mode allows the project to be installed for the current user only, without any need for elevated privileges (sudo) or system-wide changes.

To activate this mode, pass the --user (or -u) argument on main script run:

./lucidglyph.sh --user [COMMAND]

Specific modules can be blacklisted individually, disabling the desired parts of the project.

The blacklist should be provided through the --blacklist (-b) option when calling the install command and will be automatically preserved between updates. One --blacklist option can hold only one module name or glob pattern provided in literal string format (single quotes).

You can get the names of the modules by inspecting the contents of the src/modules/ directory.

The below example will prevent modules from being installed in the respective order:

• src/modules/environment/lucidglyph-freetype-properties.conf
• src/modules/fontconfig/11-lucidglyph-grayscale.conf

sudo ./lucidglyph.sh install \
    -b 'environment/*freetype-properties*' \
    -b 'fontconfig/*grayscale*'

Below are the lists of fonts that are recommended (and not) for use with lucidglyph installed. These are subjective, opinionated suggestions, not strict guidelines - hence, lucidglyph does not enforce any font overwrites by itself.

Fonts in the "Not Recommended" group are generally not recommended for usage due to poor legibility and improper geometry at small sizes after stem-darkening (see Details).

Serif:

• Noto Serif

Sans-serif:

• Inter, Adwaita Sans
• Noto Sans

Not Recommended:

• Cantarell

Monospace:

• DejaVu Sans Mono
• MesloLG, Menlo
• JetBrains Mono

This project does not assign the hinting settings forcefully, only "suggesting" the system to use the "Slight" hinting if no other option is set. This is the intended behavior since hinting settings are usually really taste-dependent, so the final choice was left to the end user.

Starting from version 133 (February 2025), Chromium now uses the self-written replacement for FreeType called Fontations, as a new font system, with Skrifa library being responsible for rendering in it.

Skrifa currently lacks any stem-darkening support¹, which is one of the crucial parts of the lucidglyph project (see Details).

In Chromium 139.0.7258 the flag that was previously used to turn back the FreeType rendering backend was completely removed² with one of the contributors stating that they "...no longer intend to carry the FreeType support."³.

There's nothing more I can do here until the Fontations stack matures enough to support the required functionality other than suggest switching your browser of choice to any non-chromium-based one or make use of scaling and zoom features.

For the software that is still based on older Chromium versions, you can switch to FreeType rendering in several ways:

Command Line
Launch the software with the --disable-features flag:

$ <software> --disable-features=FontationsFontBackend

Manual

1. Open this link: chrome://flags/#enable-fontations-backend
2. Set the flag to Disabled.
3. Restart the browser by closing the window.

You can track the detailed progress on this issue here.

While GNOME does use the grayscale anti-aliasing method by default, there are a few Linux distributions that change this setting to the sub-pixel method, making the font rendering appear incorrect after the tweaks from this project.

To check if your system is configured properly:

1. Open the terminal
2. Execute the command below to query the current configuration:

   gsettings get org.gnome.desktop.interface font-antialiasing

3. If the output of the above command looks like this:

   'rgba'

4. Then execute the command below to set a proper font anti-aliasing:

   gsettings set org.gnome.desktop.interface font-antialiasing grayscale

To revert the above changes to a system defaults just execute this command:

gsettings reset org.gnome.desktop.interface font-antialiasing

By default, the vanilla Plasma desktop environment does follow the fontconfig rules, including the anti-aliasing settings, but in some cases this behavior gets overwritten, causing an improper font rendering due to misconfigured anti-aliasing parameters.

The problem arises due to a regression in the KDE Plasma text rendering stack, which forces an incorrect configuration when fractional scaling is used.

This issue is already being tracked⁴ on the KDE tracker but still requires a manual intervention.

To fix it:

1. Open the System Settings
2. Go to the "Appearance & Style" - "Text & Fonts"
3. Ensure that "Sub-pixel rendering" is set to "None"

Rendering of some fonts dark (foreground) on light (background) (aka light themes) in Kitty may discard most of the applied stem-darkening (see Details) due to the nature of gamma correction. The lack of darkening is easily visually detectable by very thin-appearing glyphs.

To remedy this issue, append this modified text_composition_strategy parameter to Kitty's user configuration file:

text_composition_strategy 1.7 0

Decrease or increase the value 1.7 to decrease or increase the emboldening effect, respectively.

Sway Window Manager does not respect global font anti-aliasing settings, resulting in subpixel anti-aliasing being used instead of grayscale.

To remedy this issue, append the following content to your window manager configuration file:

output * subpixel none

For a more detailed explanation of this entry, please refer to the official SwayWM man page:

man sway-output | grep -A8 "output <name> subpixel"

• Environment variables:

  • Stem-darkening (fonts emboldening) for autofitter (including custom darkening values), type1, t1cid and cff drivers. This feature improves visibility of the medium and small-sized fonts. Especially helpful on the low pixel density (LowPPI) outputs. Basics Article and Usage Documentation.

  • Disable synthesized bold fonts in Qt-based software. There is an issue that causes bold glyphs to appear heavy in variable fonts. Red Hat reports: Bugzilla, Fedora tracker. Qt report.

• Rules for Fontconfig:

  • Enforce grayscale anti-aliasing (disable sub-pixel). Grayscale anti-aliasing should be enforced in the system to make the stem-darkening from the above work properly.

  • Suggest the client to use the "Slight" font hinting style, which is the preferred style for both preserving the original geometry and providing legibility. Only applied if the target system misses any hinting configuration.

  • Stem-darkening fallback through emboldening. This rule compensates the lack of stem-darkening on very small glyph sizes (caused by #9) by utilizing the built-in emboldening feature of Fontconfig. It is important to note that there is a significant chance that some software may not support this feature.

  • Reject usage of "Droid Sans" family for Japanese and Chinese characters and force the environment to use other fonts. Stem-darkening does not work well with this typeface, causing characters over-emboldening.