ddcutil is a Linux program for querying and changing monitor settings, such as brightness and color levels.

Most monitors, other than laptop displays, have a Virtual Control Panel (VCP), which implements features defined in the Monitor Control Command Set (MCCS). Typically, ddcutil communicates with the monitor's VCP over an I2C bus, as per the Display Data Channel/Command Interface Standard (DDC/CI).

Alternatively, some monitors (e.g. Eizo ColorEdge, Apple Cinema) provide a USB interface to the VCP, as described in the USB Monitor Control Class Specification. ddcutil can communicate with these monitors over USB instead of I2C.

A particular use case for ddcutil 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.

The tarball/github project builds both command line (ddcutil) and shared library (libddcutil) executables. The command line executable does not depend on the shared library.

For detailed information about ddcutil, see the project website: www.ddcutil.com.

In particular, for a summary of key post-installation steps, including loading driver i2c-dev, see Post-Installation Checklist. More generally, for instructions on building and configuring ddcutil, see Installation and Configuration

The ddcutil FAQ describes the causes and workarounds for many common (and not so common) issues.

Once ddcutil is installed, online help is also available. Use the --help option or see the man page:

$ ddcutil --help
$ man 1 ddcutil

References to the relevant specifictions can be found at www.ddcutil.com/bibliography.

If ddcutil is successfully built but execution fails, command ddcutil environment probes the I2C environment and may provide clues as to the problem.

Please direct technical support questions, bug reports, and feature requests to the Issue Tracker on the github repository. Use of this forum allows everyone to benefit from individual questions and ideas.

When posting questions regarding ddcutil configuration, please execute the following command, capture its output in a file, and submit the output as an attachement.

$ ddcutil interrogate 

For further information about technical support, see https://www.ddcutil.com/tech_support.

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

Sanford Rockowitz rockowitz@minsoft.com