Better ClearType Tuner

A better way to configure ClearType font smoothing on Windows.

Quickly set font-smoothing settings in Windows 7, 10, or 11, and know what you are getting, unlike using the broken ClearType tuner that is built-in to the OS. This program includes all font-smoothing settings that I have found to work in modern Windows, and does not expose settings that are non-functional.

• Enable or disable font antialiasing.
• Choose between Grayscale antialiasing or subpixel antialiasing using RGB or BGR subpixel layouts. "ClearType" technology specifically refers to RGB and BGR subpixel antialiasing.
• Edit the text contrast and other text rendering settings.
• Preview the results at several font sizes and see a zoomed-in view to better-understand what is going on internally!
• Every setting is previewed live, through all three of the rendering paths Windows actually uses: GDI, DirectWrite ClearType, and DirectWrite grayscale.
• Compatibility varies between apps. Windows has multiple text rendering APIs and apps typically use one or the other and may not respect all of settings as configured in the operating system. The three previews show you which is which.

Download from the Releases Section, extract, and run.

The zip contains two builds of the same program. Run whichever one suits your machine, and keep its .exe.config file next to it:

Windows has two low-level text rendering methods: GDI and DirectWrite. Apps typically only use one or the other and some apps behave differently. For example, Firefox is known to use DirectWrite, but in my tests Firefox ignores the Enhanced Contrast setting.

More importantly, DirectWrite is not one thing. It rasterizes glyphs down one of two paths, and each application chooses for itself:

This is why some apps appear to ignore settings that demonstrably work elsewhere. A WinUI app draws its text onto composition surfaces that may be transparent, transformed or animated, which cannot carry per-subpixel coverage, so it rasterizes grayscale no matter which antialiasing mode you select.

Better ClearType Tuner previews both paths side by side, live, so you can see which setting moves which.

The selected antialiasing mode controls GDI-based apps fairly reliably, but is only a hint to DirectWrite apps, so apps may end up using a different antialiasing mode than what you selected.

TextContrastLevel is the one Avalon.Graphics value still not exposed by Better ClearType Tuner. It is a WPF 3.5-era setting with no reader I could find in modern Windows; the TextContrastLevel value is written at its documented default of 1 so the full set of keys exists in case something I'm not aware of cares to read it.

Administrator permission is no longer needed to change text rendering settings. Everything going into the Windows Registry is written under HKEY_CURRENT_USER now. Better ClearType Tuner versions up to 1.6.2 also wrote GammaLevel and PixelStructure under HKEY_LOCAL_MACHINE, and that required administrator permission. It had no benefit because the keys under HKCU override the keys under HKLM anyway. A UAC prompt can still appear in one case: clearing Override DirectWrite defaults on a machine where an older version of this program (or another tuner) left a machine-wide key behind, since removing that still requires administrator rights.

A checkbox Override DirectWrite defaults decides whether the Avalon.Graphics registry key exists at all. A clean Windows installation does not have it, and that is not always the same as having it with default-looking values in it. DirectWrite falls back to settings of its own, and at least some applications behave differently depending on whether the key is there or missing. Clearing the checkbox removes the keys from the Windows Registry; the settings boxes then show what DirectWrite falls back to, read from DirectWrite itself rather than assumed.

Note that Microsoft documents the Avalon.Graphics GammaLevel default as 1900, but experiments show that DirectWrite does not use that number. When the DirectWrite API is asked what it resolves to with the key absent, it answers with a gamma of 1.8 — a GammaLevel of 1800.

DirectWrite text rendering appears to have been designed with support for having different text rendering settings on different monitors. However, this appears to be entirely non-functional in modern Windows, so this program sets Avalon.Graphics registry keys for all monitors the same.

Sources / further reading

• This project's investigation notes: ClearType Investigations (wiki) — and discussion in #11.
• Microsoft documents per-display WPF/Avalon keys such as PixelStructure under SOFTWARE\Microsoft\Avalon.Graphics\<display> (ClearType Registry Settings — WPF), while GDI font-smoothing orientation is a single SystemParametersInfo value (SPI_*FONTSMOOTHINGORIENTATION) with no monitor handle. DirectWrite can load per-HMONITOR defaults only when apps call CreateMonitorRenderingParams (multi-monitor how-to).
• Independent mapping of what each cttune.exe step writes: Reupen — What does each step in the ClearType Text Tuner do? (2025).
• Longer discussion of ClearType (setting planes, tools, and mixed RGB/BGR desks as a corollary): ClearType · HCI Nerdz topic · essay.

For those who want more advanced text rendering tweaks, I strongly recommend MacType. MacType enables much deeper customization of text rendering (although it doesn't work with everything) and is particularly useful on displays that use subpixel layouts not natively supported in Windows.