Re: real world wide gamut monitor - HP LP2475w - calibration with Spyder3
Re: real world wide gamut monitor - HP LP2475w - calibration with Spyder3
- Subject: Re: real world wide gamut monitor - HP LP2475w - calibration with Spyder3
- From: C D Tobie <email@hidden>
- Date: Mon, 7 Dec 2009 12:39:40 -0500
HI Steven,
Your results are fairly typical. Without, as you note, a lab-grade
device for comparison, its not a matter of determining accuracy, but
rather consistency and grouping. We find, comparing affordable
calibrators to a lab-standard, that the X-Rite devices tend to group
on one side or lab-standard device, and Spyder devices tend to group
on the other. This tendency causes those who would like to do their
own comparison tests, but who don't have access to a lab-standard, to
use the most costly of their devices (typically an EyeOne Pro) as a
pseudo-standard, and thus assume that the X-Rite devices are more
accurate, then in fact they are just more consistent to one another.
This gets even messier when you consider that even two lab-standards
devices of different makes and models don't even agree as closely as
one would expect them to; producing whitepoints, for instance, that
might vary by 300 or 400 degrees.
The older Optix device (which is in rather a category by itself, as it
was not developed by Gretag, or by Datacolor) tended to beat out both
the Gretag (now X-Rite) colorimeters, and the Datacolor colorimeters,
on older displays, with more sRGB-sized gamuts. On newer wide gamut
displays, the Spyder3 often comes up with the best colorimeter-based
results, though this tends to vary with the particular wide gamut
display in question. I've also heard from a number of users that an
off-the-shelf Spyder3 does about as well (sometimes better) than an
EyeOne Display 2 that has been custom tuned to the wide gamut display
in question.
Due to the favorable results on wider gamut screens with the Spyder3,
a number of wide gamut display and/or calibration software developers
have chosen to add support for it in their proprietary software, and a
few have even chosen to offer display bundles including it, while
others continue to bundle the Display2, though I am not aware of any
that still bundle the Huey.
So, messy as this may sound, for some aspects of calibration,
spectrophotometers usually do the best job, for other aspects, the
best of the colorimeters are preferable; and which colorimeter is
preferable for a given display depends on the particular display make
and model (and possibly other factors, such as phase of the moon).
There isn't even any guarantee that the device bundled with a
particular display will give the best results on that display. Sorry
if this doesn't offer a simple, clear answer, but no everything can
boil down to a single simple answer.
C. David Tobie
Global Product Technology Manager
Digital Imaging & Home Theater
email@hidden
Datacolor
www.datacolor.com/Spyder3
On Dec 7, 2009, at 11:43 AM, Steven Dobbelaere wrote:
Hi,
I have doubts about the gamut of my monitor profile. I've did some
investigation but have still a lot of questions (even after reading
the "Monitor Calibration" thread from a couple of weeks ago in this
list).
The monitor I have is an HP LP2475w, a wide gamut display.
It uses a wide CCFL backlighting lamp and has a color gamut of 92%.
http://h10010.www1.hp.com/wwpc/uk/en/sm/WF05a/382087-382087-64283-3884471-3884471-3648442.html
In the states the gamut seems to be 102% ?
http://h10010.www1.hp.com/wwpc/us/en/sm/WF05a/382087-382087-64283-72270-3884471-3648442.html
QUESTION1: What is the reference gamut to express a gamut coverage?
92% of what gamut?
Eizo and NEC use the AdobeRGB gamut as reference, but is there a
kind of an ISO to express the gamut volume?
Here they compare with the NTSC color gamut:
http://www.tftcentral.co.uk/speccontent.htm#gamut
I first used an EyeOne display2 for creating my monitor profile.
However, EyeOne Display2 devices have a specific calibration matrix
when they are bundled with
high-end monitors. That is a clear indication for me that a standard
device is not suited for wide
gamut displays.
Therefore I bought a Spyder3 elite because this device is suited for
wide gamut displays.
http://spyder.datacolor.com/product-mc-s3elite.php
New Support for Next Generation Displays. Patented Spyder3 optical
design and color engine enable precise calibration and profiling of
the latest in wide gamut, LED backlight and AdobeRGB displays.
Comparing my monitor profiles measured with the EyeOne Display2 and
the Spyder3 revealed some surprising results.
Settings: native white point - gamma 2.2 - brightness=100 and
contrast=100 - 16-bit LUT / CAT02 / icc v4
All profiles are created with basICColor.
http://img43.imageshack.us/img43/9751/e1d2spyder3.jpg
As you see in above screenshots the gamut of the monitor profile
created with the spyder3 is smaller then the EyeOne Display2.
I returned my spyder and received a new one. However, the result was
the same.
I compared again the monitor profiles from an EyeOne Display2, the
Spyder3, the EyeOne Pro and the Colormunki.
Again the same results:
Settings: native white point - gamma 2.2 - brightness=100 and
contrast=100 - 16-bit LUT / CAT02 / icc v4
http://img51.imageshack.us/img51/5036/e1d2colormunki.jpg
http://img31.imageshack.us/img31/5659/e1d2e1pro.jpg
When i compare my profiles with profiles from other users then they
are very similar.
http://img704.imageshack.us/img704/3104/e1d2othere1d2.jpg
http://img43.imageshack.us/img43/9927/spyder3otherspyder3.jpg
QUESTION2: Which profile is now most accurate?
I think this can only be answered when:
comparing with a device that uses a calibration matrix
comparing with measurement data from a spectroradiometer
What i have is the EDID info from the monitor (I assume not from my
monitor but for all HP LP2475w monitors).
When i make a profile with these values and compare it then the
Spyder3 profile is closer to the gamut of the EDID profile in the part
where the E1D2 is much larger.
http://img51.imageshack.us/img51/3520/comparedwithedid.jpg
What I actually expect is a profile that is covering most of the
AdobeRGB gamut.
THe Spyder 3 should be the recommended tool, but it fails and the
I1D2 profile is much larger??
http://img704.imageshack.us/img704/9219/spyder3versusadobergb.jpg
http://img704.imageshack.us/img704/8173/eyeonedisplay2versusado.jpg
When I use the volume values then I get a coverage of 111% for the
I1D2 profile and a coverage of 98% for the Spyder3 profile.
Good, the gamut value is not that bad but what does it tell me? If
the gamut coverage of a monitor is 92% then the 92% can be:
- inside the reference gamut
- partly inside the reference gamut
QUESTION3: Am I correct that the gamut value doesn't tell how well
the reference shape is followed?
QUESTION4: Is there a reference wide gamut (CCFL) profile available
created with a spectroradiometer that I could use to see how
accurate my
colorimeter is?
THx!
Steven
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