Monitor property control
Modern monitors contain lots of control functionality. They interfere with a proper calibration. So it is for some users useful to set them to a state which corresponds to a certain ICC profile or disable such settings at all.
If the properties are simple, they may be set to good defaults before calibrating such a display device. Some monitors provide higher than 8-bit per pixel LUT's, sometimes even for each colour channel. In this case it is more promising to calibrate these LUT's directly and leave the graphic cards LUT untouched. This help in providing more of the 256 steps possibly with todays VGA busses.
Possibly controls are brightness, contrast, monitor and grafic card LUT's, auto adjustment features ...
Candidates for holding a according API are Xorg or HAL. Work is already done in the ddccontrol project. Of course Xorg includes i2c capabilities, which is under discussion (http://lists.freedesktop.org/archives/xorg/2007-August/027105.html) to expose as a library (in RandR). The communication with a monitor can happen eigther over DDC/CI (http://en.wikipedia.org/wiki/Display_Data_Channel) or a separate UBS cable.
- Monitor Device Class Definition (http://www.usb.org/developers/hidpage/) specification at usb.org
- i2c (http://www.i2c-bus.org/) specification
- ddccontrol (http://ddccontrol.sourceforge.net/) open source project
- Apple Cinema Display control (http://www.technocage.com/~caskey/acdctl) open source project
- Ookala MCF Monitor Calibration Framework (http://ookala-mcf.sourceforge.net/) C++ open source project from HP
- Specifications (http://www.freedesktop.org/wiki/Specifications) list at freedesktop.org
- XV calibration thread (http://lists.freedesktop.org/archives/xorg/2007-August/027469.html) Graemes response at fd.o
- Xcalib thread (http://lists.freedesktop.org/archives/openicc/2005q1/000094.html) at the OpenICC list about calibration paths