[argyllcms] Dell U2413 calibration / can a wide gamut display provide a superior sRGB image?
- From: Joshua Hoblitt <jhoblitt@xxxxxxxx>
- To: argyllcms@xxxxxxxxxxxxx
- Date: Mon, 29 Apr 2013 00:14:54 -0700
Hello,
I started down the road of "home monitor replacement" a few days ago as
my home LCD panel was really showing it's age. I also decided to switch
from one 24" panel at home to 3 x 24" to match my office desktop setup
in terms of screen real estate. I did some research and decided I did
not want a wide gamut panel at home after my experience with Dell U2410s
@ $day_job. My work setup is 3 x Dell U2410s running the less than
ideal factory sRGB preset without calibration. Home usage is mostly
text with some RTS games and raw photo conversation / print proofing for
online print services (no home photographic printing) in sRGB (I have
never used aRGB in my workflow). Work / Home environment is completely
Linux. I have a DTP94 that I purchased in ~2008. I also should note
that I have very little experience with calibration and this weekend is
my first attempt to really do much with the DTP94.
After reading many positive reviews I decided to try a single HP ZR2440w
instead of jumping in on 3 monitors at once. The panel in the HP is yet
another better/cheaper IPS variant with 6bits per channel + FRC, which
probably puts it close to 8bits per color channel. The ZR2440w arrived
last Wed. I added it as a second monitor to my home machine, and while
the color curves look pretty good even without being calibrated, I swear
that are some sort of halos around bright text on dark back grounds. I
can't see it with my eye right up on the screen but it's there from the
distance; I'm wondering if this some sort of FRC affect??? It also had
some sort of strange sharpening issue going on that was slightly
blurring text (there are 5 levels of hardware sharpening, default is 4,
5 causes bad artifacts) that seems to have stopped now. It's possible
that there was some sort of cabling crosstalk going on under my desk
before I removed and reconnected all cabling. Before the strange text
sharpening issue solved itself I'd decided to return the HP and order a
U2413 to try to calibrate it.
The Dell U2413 arrived yesterday and I removed my old LCD so it could be
installed side by side with the HP. The out of the box color response
reminds me a lot of the U2410s @ work but the screen doesn't look as
"dirty". I assume that's the change in the AR coating used. I will
happily note that the sRGB preset is much better looking. Side by side
with the HP, the sRGB preset still gives what looks like much greater
color saturation. I don't know how to calibrate for just saturating so
I haven't explored that. It could be that this is just the different
between a true 8bit display and a 6bit+FRC disable?
I quickly discovered trying to calibrate the Dell with my DTP94 that at
least the green channel isn't properly detected by the puck. Sitting
next to the HP I suspect that, as per the discussion of wide gamut
displays in the argyllcms docs, that the spectral peak for the green
light source isn't playing nicely with the green filter in the
colorimeter. The Dell's white balance is very, very green out of the
box on any of the factory preset options and the colorimeter only helps
dial it down a little. The green tint isn't surprising based on the
fact that this monitor has a GB-LED back light. So, after 2 days of
playing with both monitors this leaves me with a bunch of questions that
I was hoping someone in the argyllcms community could help answer some
or all of:
1) What is the best [sub $1k] calibration solution for the Del U2413?
The Dell sourced solution for this monitor seems to be an i1 DisplayPro
+ some Dell branded calibration software that can set the custom LUT
profiles in the monitor. Googling turned up some correction files for
this monitor / colorimeter combination here:
http://dispcalgui.hoech.net/colorimetercorrections/?get&type=ccss&manufacturer=Dell&display=DELL%20U2413&instrument=i1%20DisplayPro%2C%20ColorMunki%20Display%2C%20Spyder4&html=1
http://dispcalgui.hoech.net/colorimetercorrections/?get&type=ccmx&manufacturer=Dell&display=DELL%20U2413&instrument=i1%20DisplayPro%2C%20ColorMunki%20Display&html=1
2) Is messing around with a wide gamut display trying to get better over
all image quality than a 6bit IPS panel a hopeless pursuit? Ie, I'd be
better off returning the Dell and getting 2 more HPs.
3) Since I only need sRGB support, can I make a wide gamut display
approximate sRGB for non-collor managed apps via a calibration profile?
4) It appears that virtually all image tools and my desktop enviroment
(gnome) only support one screen/display profile at a time. Since I use
xinerama to spread my desktop across 3 screens, is there a way of
profiling each screen individually and then combining the 3 profiles
into some sort of "mean profile"?
5) Is there a tool on Linux that will allow setting the 2 custom LUTs
internal to the monitor instead of the video card LUT?
Thanks,
-Josh
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