[argyllcms] Re: Comparison of Monitors on Linux and Mac
- From: Graeme Gill <graeme@xxxxxxxxxxxxx>
- To: argyllcms@xxxxxxxxxxxxx
- Date: Sun, 12 Oct 2008 00:25:27 +1100
Timothy Hattenberger wrote:
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.
You can't expect calibration alone to make two monitors look identical,
unless they are already very well matched in terms of colorant
chromaticities etc.
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.
It depends on how you use it. The profile can be stored so that it
can then be retrieved as the current profile for that display (-I)
but dispwin also loads the calibration portion of the profile
into the hardware.
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?
That's the usual situation for separate profiling. If you supply a calibration
file to dispread, then it will take the measurements with that calibration
in place. You could use the same .ti1 file on the two monitors with their
individual calibrations, and then run verify on the resulting .ti3 files.
So, does anyone have any clues?
To get a really good match, then you need to be using the profile
as well as the calibration. That means using the profile as the destination
part of a CMM managed process. You can do this with Argyll tools if
you like (ie. cctiff in combination with some non-color managed
program to display raster files), or by using color aware applications
properly. It isn't always plain sailing to know what's going on with
regard to the various color transformations that take place in
a color managed workflow though.
Graeme Gill.
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