Auto-EDID Profiles Results

First, thanks for everyone that contributed ICC profiles. I’ve received over 800 uploads in a little under 24 hours, so I’m very grateful.


Total profiles scanned: 800
Profiles with invalid or unlikely primaries: 45
EDIDs are valid 94.4% of the time

This resulted in the following commit to colord:

commit 87be4ed4411ca90b00509a42e64db3aa7d6dba5c
Author: Richard Hughes <>
Date:   Wed Apr 24 21:47:14 2013 +0100
    Do not automatically add EDID profiles with warnings to devices

I’ll explain a little about what these numbers and the commit means. The EDID reports three primaries, i.e. what real world XYZ color red, green and blue map to. It also tells us the whitepoint of the display. From basic color science we know that

  • If R=G=B, we should be displaying a black/gray/white color without significant amounts of red green and blue showing
  • The reported gamut of colors should not be bigger on real hardware than theoretical archive spaces like ProPhotoRGB.
  • If R=G=B=100%, then we should have a good approximation of D50 white
  • The temperature of the display should not be too cold (>3000K) or too warm (<10000K).

There are actually 11 checks colord now does on RGB profiles, similar to the checks done above. If any of the 11 checks fail, the automatically generated profile is not used. The user can still add it manually if they want and then of course it will be used for the monitor, but we don’t break things by default for 5.6% of users.

If anyone is interested, the results were generated by this program, and the raw results are available here. My personal take-home messages you can take from this file are:

  • Sometimes blue and green are the wrong way around (Samsung SyncMaster)
  • Vendors need to use something other than random binary data (AU Optronics)
  • If you don’t know what a whitepoint is, don’t try and guess (Sharp and Lenovo YT07)
  • Projectors generally don’t really know/care what values to use (OPTi PK301 and In Focus Systems)

There’ll be a new colord release with this feature released in the next couple of weeks.

Published by


Richard has over 10 years of experience developing open source software. He is the maintainer of GNOME Software, PackageKit, GNOME Packagekit, GNOME Power Manager, GNOME Color Manager, colord, and UPower and also contributes to many other projects and opensource standards. Richard has three main areas of interest on the free desktop, color management, package management, and power management. Richard graduated a few years ago from the University of Surrey with a Masters in Electronics Engineering. He now works for Red Hat in the desktop group, and also manages a company selling open source calibration equipment. Richard's outside interests include taking photos and eating good food.

3 thoughts on “Auto-EDID Profiles Results”

  1. I have two identical screens here at work, but they show slightly different colours. (it’s especially visible on gray and white)

    I haven’t calibrated them, and it happened with at least Fedora 16 and Fedora 18. (both running their respective GNOME versions).

    Yesterday when I sent you the generated EDID profiles, I noticed there were two of them. Could the screens be reporting two different profiles, which causes the slight mismatch of colours?

    1. Nahh, the two profiles are because the “identical” displays probably have different serial numbers. Did you buy both screens at the same time and have used them for the same amount of time since new? Otherwise backlight ageing is going to be a significant difference.

      1. The two screens are provided by my employer, so I have no idea when they were bought, or whether they were used by someone else before me.

        One screen looks a bit more dull, less luminous than the other, so it could be that its backlight aged more, indeed.

Comments are closed.