Display profiles generated from EDID

If you’re running a GNOME or Unity desktop (and probably recent versions of KDE too), you may notice differences in color rendition between different applications. The difference you’re seeing is between applications that apply the system configured display profile and those that don’t. For example Eye of GNOME and Darktable do this by default, GIMP for example doesn’t…

Now, as many people have noticed most displays render color quite differently, and display profiles are a technical means to correct that to some degree. There are several means for obtaining a display profile, one is to buy a measurement device (called a colorimeter) and actually measure your particular display. Some vendors supply a display profile ICC file on a CD that came with the display. And lastly more recent displays apparently provide information which can be used to generate a display profile via EDID (which is a protocol for information exchange via VGA/DVI/HDMI). The respective methods have been listed in order of decreasing accuracy. For a bit more in-depth information you might want to consider reading this.

At least since distributions have been shipping colord and GNOME Color Manager (so I’m guessing since Oneiric for Ubuntu users), colord actually queries your display via the EDID protocol, to extract the required information to generate an automatic display profile, which allow certain applications to correct for the displays behavior.

We Need You

Now, recently we’ve begun to have the impression that some vendors may be shipping bogus information in their displays (possibly under the assumption that it would not be the used anyhow). But currently we have no information to substantiate this.

Please read this and this first before continuing.

I’d like to ask you, to submit your EDID generated profile to the gnome-color-manager-list (you can post to the list without subscribing, your submission will be moderated and thus will take a few days to turn up) including the following:

  • Subject: [EDID] Display Make + Model
  • Attach ~/.local/share/icc/edid-*.icc
  • Display Make (if it’s a laptop, then the laptop make)
  • Display Model (if it’s a laptop, then the laptop model)
  • The Displays Age (approx. how long ago did you buy it)
  • Duty Cycle (light usage on average a few hours a day, heavy usage approx. 8 or more hours a day).
  • The output of  xprop -display :0.0 -len 14 -root _ICC_PROFILE
  • Subjective Impression (download this SmugMug calibration image, and load it into GIMP, then go the GIMP’s Preferences, to go Color Management, and then check/uncheck Try to use system monitor profile while keeping an eye on the image, tell us what looks most realistic to you (checked/unchecked) and why…

After more than 2000 submissions colord-0.1.34 was released which should detect and disable cases where the displays are supplying bogus information via EDID. Based on the current statistics it seems 4% (or thereabouts) of the displays supply bad information.

Working around bad EDID

Assuming some vendors actually provide bad information via EDID, you might need a way to disable this automatically generated profile. In older versions of GNOME Color Manager (3.6 and earlier) there wasn’t an easy way to disable this. There is however a feasible workaround. Install argyll on your system. Then assign /usr/share/color/argyll/ref/sRGB.icm to your display. (Go to the GNOME System Settings, Choose the Color applet, Choose your display, click Add Profile, select Other Profile, and then select Argyll’s sRGB.icm).

Posted by on April 14, 2013 in color