[argyllcms] Comparison of Monitors on Linux and Mac

  • From: Timothy Hattenberger <thattenberger@xxxxxxxxx>
  • To: argyllcms@xxxxxxxxxxxxx
  • Date: Fri, 10 Oct 2008 17:11:07 -0700

I need to be able to view the same image on Mac and Linux and have them look the same. I've eliminated as many variables as possible.

2- 20" Apple Cinema - One on the Linux and one on the Mac
ArgyllCMS used to calibrate and profile on each OS (latest version, v1.0.03 I believe)

After creating the profiles using the same settings, on each platform, I then load them using ColorSync on the Mac and dispwin on Linux. When I compare a set of images they are pretty close, but there is definitely a color difference and it's more pronounced in some images over others (to be expected). For example, one monitor is more red than the other.

My current understanding is that on Linux, when I run dispwin, it's loading RGB VCGT calibration curves into the xserver somewhere (i.e. not into the graphics card) and the rest of the profile is never used. So, in order to make sure it's exactly, the same, I'm using untagged images on the Mac. So essentially only the VCGT curves are being 'used' there as well. I verified this on the Mac side by comparing the same untagged image loaded in Preview (a color managed app) and Shake (a non-color managed app) and they look identical. I've been working on this a while and am getting a little frustrated.

In fact, I got better results when I used Eye-One match on the Mac, and RSR cineProfiler on the Linux box, not only in comparison, but in overall profile performance (e.g. there was a lot less contouring). I believe I could probably tweak the argyllcms settings eventually to get a better looking profile, but I'm not even at the point of having the images match yet.

I have a suspicion that this could be related to the monitors, but don't know how to eliminate that. If I run dispcal -yl -R and look at the native responses of the monitors, what I get (roughly) is that one of the monitors has a native white point of ~6850K and the other is ~6300K. I would guess the same monitors should have much closer native responses. What I would like to do is be able to make an input .ti1 file with just a few patches, measure the XYZ values and calculated CIEDE94 values. The only question is if it's possible to make those measurements with the calibration in place (i.e. w/o blowing away the VCGT LUTS). Is that possible?

So, does anyone have any clues?

Tim H.

The information contained in this message and its attachments is
confidential and proprietary to LAIKA, Inc.  By opening this email
or any of its attachments, you agree to keep all such information
confidential and not to use, distribute, disclose or copy any part
of such information without the prior written consent of LAIKA,
Inc.  If you are not the intended recipient of this message, any use,
distribution, disclosure or copying of such information is prohibited.
If received in error, please contact the sender.

Other related posts: