[argyllcms] Re: Bad measurements & white point calibration with Argyll 0.7b7 and GretagMacbeth i1Display 2
- From: Leonard Evens <len@xxxxxxxxxxxxxxxxxxxxx>
- To: argyllcms@xxxxxxxxxxxxx
- Date: Wed, 09 Jan 2008 23:39:22 -0600
On Thu, 2008-01-10 at 09:43 +0900, Craig Ringer wrote:
> Hi folks
>
> I'm having some severe issues getting decent results out of an i1Display
> 2 using Argyll 0.7b7 . If I use dispcal to adjust the gains to target a
> D65 white point I end up with a bright purplish-blue display.
>
> I've seen the same issues with lprof, which uses a slightly older
> version of the Argyll meter reading code.
>
> The same hardware works fine with the GretagMacbeth i1Match software.
>
> This issue might be best illustrated visually, so I've provided some
> photos of the display output along with information on the testing
> procedure, additional hardware details, etc at:
>
> http://www.postnewspapers.com.au/~craig/argyll7b7_blue/problem_report.html
>
> I'm not sure where to go from here, so I was hoping someone else might
> be able to detail similar issues or suggest a few tests that might
> reveal more. I can provide things like calibration run files if that'd
> be useful.
I'm still too new to color management to help you much. Let me just say
that I've been using both Lprof and argyll to calibrate and profile
monitors. I work mainly under Linux, but I have Windows XP on the same
(dual boot) machine, so I can switch back to that for comparison. First
I started with my six year old CRT monitor and had some problems. In my
case, everything ended up too dark with little contrast with the profile
in place, but the colors looked right. It turned out that the problem
was that I hadn't set the luminosity high enough. Because of the age of
the monitor I had problems with luminosity, but setting it as high as
possible I got not unreasonable results.
Since then I got an LCD monitor (Samsung 226CW). LCD monitors can be
tricky since contrast and brightness mean different things than for CRT
monitors and how you go about using the monitor controls is different.
Indeed just what you should do can depend on the specific monitor.
I found the advice on the argyll web page about how to proceed for LCD
monitors pretty good for my monitor. It advises using the default
setting for "contrast" which for my monitor is 75 percent, and then
working from there. I also found the discussion in Real World Color
Management about LCD monitors generally helpful.
In any case, I managed to get a reasonable result.
I also went back to Windows XP and used the i1Match software. But not
wanting to disturb the monitor settings I had come up with under Linux,
I left those alone and just produced a profile.
Since the Windows desktop is somewhat different from the Linux Gnome desktop,
and since I can't do a side by side comparison, I can't say they look
exactly the same. But I don't think there is any obvious difference.
With my present settings, my gray desktops look gray but in both cases
there may be a very slight bluish tint compared to what I remember for my old
CRT, which may have in fact been too yellow.
In any case, I expect to go back and do the monitor calibration/profiling
again when I understand everything better.
> --
> Craig Ringer
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