Profileling problems with hp lp2475w

[IanWorthington]

I'm trying to calibrate an HP LP2475W monitor using the Monaco Optix 2.0 software with the X-rite DTP94 puck (which I understand has a gamut suitable for this monitor) and am far from sure I can rely on the generated profile.

Setting up the white point works fine as does fine-tuning the brightness and generating the color profile but between these, when adjusting the contrast and brightness, the measurement cursor stays at about the 75% point, regardless of any changes I make using the monitor controls (There's actually a quick  jump in the direction I move the control, but then it returns to the 75% point).

If I ignore that, and using suggested Brightness and Contrast settings for this monitor from tftcentral.co.uk I rebuilt an icm profile this evening. I ended up with:

black point: 0.14 cd/m2
white: 77 cd/m2
Average dE < 1.0
Max dE = 3.08 (for L/a/b target: 97.1/-0.1/2.4, measured: 99.6/-1.6/3.5)

Then, using the lcd tester at lagom.nl, I was unable to see any checkboard
pattern below black 2 (which I think is good) or from 247-254 (which I believe
is very bad). Gamma using their chart seems to be between 1.6 and 1.9 rather
than the 2.2 the calibrator is reporting.

I do notice that the large dE occurs for near white values: would this concur
with the results of the lagom white checkboard?


Any thoughts on how I can get a better profile with a more accurate gamma and which doesn't clip so much highlight tone?

ian

[bill t.]

I think you're just way too dark at 77 cd/m2, especially for an LCD.  Try 120 or 140 and see if it's better.  I got into very dim monitor levels a while back, and honestly it didn't help me make good prints.

[Scott Martin]

Any thoughts on how I can get a better profile with a more accurate gamma and which doesn't clip so much highlight tone?

Make sure the Contrast, RGB and gamma settings on the monitor are left at their native settings. If they are adjusted it messes up the calibration process and you'll get delta E issues in the highlights especially. Using a monitor's "Reset" or "Restore Factory Defaults" feature restores those native setting. The Brightness adjustment is the only hardware adjustment that you want to mess with on any LCD display. Let the software (not hardware) control the color of white, if needed.

As for the luminosity, use whatever gives you a match to paper white under your lighting. Of course, good Solux lighting is always a smart investment that aides this connection.

You might also try downloading the Color Eyes Display Pro software and try it out in demo mode with your DTP94. It's a nice step up that includes iterative calibration.

[juicy]

HP LP2475W is a large gamut monitor. DTP94 expects sRGB primaries and thus it is less than ideal for this kind of display without some kind of correction matrice. I'm not aware if there are any profiling software that works with this display and puck without problems.

J

[Scott Martin]

J, are you saying that from hands-on experience or from theory? What problems are you experiencing?

I've been traveling around with a case full of devices calibrating all kinds of devices since the 90s and am hugely impressed with a DTP94/ColorEyesPro combination, even on large gamut displays. The consistency and quality across a huge variety of devices is unsurpassed, IMO. The color scientists say the Spyder3 and it's 7 sensor configuration has an edge over the DTP94 on large gamut displays. From my own side-by-side, real world, print to screen comparisons I'm actually seeing better saturation and consistency with DTP94/CEDP on large gamut displays then with Sypder3Elite, and extremely similar results with compared with proprietary systems from Eizo and NEC. My experience suggests that a DTP94/CEDP is extremely capable on large and regular gamut devices and thus my recommendation. But I'd be happy to hear more real world, hands on observations.

[juicy]

Well, I'm also interested in hearing real world experiences about this particular setup.
My wording in the earlier post was inaccurate. When I wrote that "I'm not aware if there are any profiling software that works with this display and puck without problems" I meant that I have no knowledge of this but that there very well may be such a software. However the theory that is stated over and over says that it is somewhat unlikely without the correction tables and especially so when taking into account that LP2475W is a very cheap display marketed for office use and not as a professional graphics display.
I have this display and the original Monaco XR pro and my experiences are limited to that software. I have to test CEDP when I have the time. Anyway with Monaco software I feel the whitepoint is allways quite weird but I haven't played with it for a while.

Cheers,
J

[trinityss]

Hi,

I have also a HP LP2475w and are using now the iColor Display of Quato:
http://www.quato.de/english/icdisplay3.php

Why? Because the panel is the same as used in there Quato IP240ex monitor.
The iColor Display contains calibration matrixes for a couple of colorimeters.

I'm using a Spyder3 elite device for which there is a calibration matrix available.
The DTP94 puck is also supported, actually this is the recommended device from Quato if i'm not wrong.
They sell it as "Silver Haze Pro": http://www.quato.de/english/shp.php

Personally, I think the DPT94 puck is better... read "the inter-instrument agreement is more stable" (compared with the Spyder).
But even with a calibration matrix you are still not 100% about the measurements.

The new discuss device from BasICColor might be the better choice, but it is also much more expensive.

Just ask Quato for a trial key and give it a try.
77 cd/m² is indeed too low, it all depends on what you want to simulate.
More info about the correct settings can be found in this document:
http://forschung.fogra.org/index.php?menuid=62&reporeid=122&getlang=en

Kr,

[juicy]

Hi,

I have also a HP LP2475w and are using now the iColor Display of Quato:
http://www.quato.de/english/icdisplay3.php

(________)

Kr,

Thanks, an excellent tip!
I'm testing this setup at the moment and so far it seems good. Of course this is still far from the quality of hardware calibration but otoh this setup is very affordable.

Cheers,
J 

[trinityss]

Let me know the results. I'm thinking of bying a DPT94 myself... I don't trust my Sypder3 anymore.
I would be interested in the maximum gamut that you achive when measuring with the DTP94.

Kr,
Steven

[juicy]

Hi,

I just made some comparisons in Color Sync utility comparing the profiles created with the Quato's software and the Monaco XR pro -sofware both using the same DTP-94 puck. To be honest I was a bit surprised about the results. Attached are some screencaptures. The first image shows on the left the two profiles made of the same display with the two aforementioned software packages, the wireframe is made with Quato iColorDisplay and solid is Monaco.
The image on the right: wireframe Quato, solid AdobeRGB(1998).
The second image: wireframe Quato, solid "sRGB"-display (a HP LP2065, profile made with MonacoXR)

For me it seems that despite the lack of correction matrices for wide gamut displays and DTP-94 measuring instrument in the Monaco software the results are more or less identical to those of the Quato software that uses the correction matrices. Thus I would like to ask a couple of questions from the color management gurus: Are all the results obtained with these profiling combos complete BS or is the DTP-94 after all capable of measuring much wider gamut than it's supposed to be or was the old Monaco XR pro software so advanced that it had the wide gamut correction before there were many wide gamut displays on the market???  I guess the DTP-94 is more capable than I thought. Also the weird whitepoint measurements that I was getting with the Monaco software were more or less confirmed with the Quato software (native wp of the HP2475w display seems surprisingly low at around 5500K when dimmed to around 120-140).

Any thoughts?

Cheers,
J

[trinityss]

Indeed a surprisingly result for me as well...

The gamut looks quite normal, but I would compare it also with the Adobe RGB gamut.
I'm not sure about the Adobe RGB gamut coverage.
It should be around 102:
http://h10010.www1.hp.com/wwpc/us/en/sm/WF05a/382087-382087-64283-72270-3884471-3648442.html

"Impressive performance
•   Enjoy crisp, clear, high-resolution onscreen presentation from the 1000:1 contrast ratio, sharp resolutions to 1920 x 1200, an extra-bright screen, and 102% color gamut on a 24-inch diagonal wide-aspect screen."

I was never able to make a gamut that covers 102%...


Kr,

[juicy]

Hi,

The right hand image compares the monitor profile to the adobeRGB (solid) and at least colorsync utility shows the monitor gamut to be noticeably larger than adobeRGB in the red part of spectrum.

Cheers,
J