ddcutil and ddcui

Announcements

12 May 2026

ddcutil 2.2.7 contains important bug fixes and changes in shared library libddcutil, relating to its handling of display connection and disconnection and the transient loss of access permissions for /dev/i2c devices. These changes are important for its use by KDE PowerDevil.

For details, see Notes for Recent ddcutil Releases, and Shared Library Changes for Release 2.2.7. Further detail can be found in file CHANGELOG.md in the source tree.

Gihub users Dirga Yuza (mbday123), Sultan Alsawaf (kerneltoast), and Henning Skoglunc (hkskoglund) were of great help analyzing errors encountered by libddcutil.

19 November 2025

There's now a Buy Me A Coffee page for Sanford Rockowitz, the developer and maintainer of ddcutil. If you find ddcutil useful, please consider making a small contribution to its ongoing development and maintenance.

Prior announcements can be found here.

Introduction

ddcutil is a Linux program for managing monitor settings, such as brightness, color levels, and input source. Generally speaking, any setting that can be changed by pressing buttons on the monitor can be modified by ddcutil.

ddcutil primarily uses DDC/CI (Display Data Channel Command Interface) to communicate with monitors implementing MCCS (Monitor Control Command Set) over I2C. Normally, the video driver for the monitor exposes the I2C channel as devices named /dev/i2c-n. Alternatively, there is support for monitors (such as Eizo ColorEdge displays) that implement MCCS using a USB connection. See USB Connected Monitors.

A particular use case for ddcutil, and the one that inspired its development, is as part of color profile management. Monitor calibration is relative to the monitor color settings currently in effect, e.g. red gain. ddcutil allows color related settings to be saved at the time a monitor is calibrated, and then restored when the calibration is applied.

Restrictions:

  • ddcutil does not support laptop displays, which are controlled using a special API, not I2C.
  • Generally speaking, ddcutil can be built in a virtual machine, but will not run in a VM. This is because the virtual video drivers do not implement I2C. However, if the VM is connected to a separate video card and is running a non-virtualized driver for the card in passthru mode, then ddcutil will work.
  • Nvidia's proprietary video driver may require special configuration. See Special Nvidia Driver Settings.
  • Reading and writing Table type features is implemented but untested. See Table Features

ddcutil is released under the GNU Public License, V2 (GPLV2). The source is hosted on Github.

General support questions are best directed to the issue tracker on Github. Use of that forum allows everyone to benefit from individual questions and ideas. For details, see Technical Support.

ddcui

ddcui is a graphical user interface to ddcutil, built using Qt. For further information, see ddcui Overview.

ddcui is released under the GNU Public License, V2 (GPLV2). The source is hosted on Github.

ddcui questions should also be directed the to the ddcutil issue tracker on Github.

Topics

Using ddcutil:

Commands and Options:

Installation and Configuration:

Other:

Packaging Status In Distribution Repositories

For packages maintained by ddcutil, see Installing ddcutil and ddcui from Prebuilt Packages

Those responsible for maintaining ddcutil related packages in Linux distributions should see Notes for Linux Distribution Maintainers.

ddcutil Packaging Status

ddcutil packaging status

ddcui Packaging Status

ddcui packaging status

Author

Sanford Rockowitz rockowitz@minsoft.com