Monitor calibration question

[Doc_Pit]

Hope it's OK to ask a monitor calibration question.  Not really Photoshop, but...

I'm calibrating a new Dell U2720Q monitor with i1 Display Pro.  The monitor is supposed to have a 1300:1 contrast ratio.  In two attempts, the i1 Display Pro produces a Target contrast ratio = Native and an Achieved contrast ratio =  -2147483648:1.  I'm getting the same when I attempt to calibrate my Dell U2713H monitor, which I've calibrated many times before.  I can't figure out what I'm doing that produces a negative contrast ratio.

[D Fosse · Accepted solution]

If everything else seems right, I wouldn't worry. Try to set a lower (and more realistic) range, like 350:1, and see how that behaves.

It depends on what your intended output is, but a contrast range of 1300:1 is much too high for any practical purpose.

A print on premium high-grade glossy paper has a contrast range of maximum 300:1, but normally closer to 250:1. If you print on matte paper it's down to 120:1 or so.

In other words - if you want a good screen to print match, you'll set contrast ratio to 300:1 max. If your white point is 120 cd/m², that means a black point at 0.4 cd/m².

For web those considerations don't apply, but except for home cinema in a dark room, a 1300:1 contrast range is completely wasted. Monitor manufacturers play this up as a selling point, but it's basically nonsense. Other things are vastly more important, but they're not in the spec sheet.

[NB, colourmanagement net]

Hi,

As D. Fosse writes these massive contrast ratios are largely just sales babble. 

Photoshop and monitor display calibration are inseparable IMO, I think its fine to ask here, it’s a good place to look for experienced users. Although, this may be an X-Rite question ideally -X-Rite may have somewhere you can look for help.

Try the tests below first though. save time. 

First: to avoid changes during calibration - let the display warm up for an hour thius time, most are OK within 30 min, but I tested an HP office screen recently and that was still getting brighter very gradually 'til it had been on 1:40. Once I'd waited it calibrated great.

Next: I would suggest that rather than targeting a contrast range in the X-Rite software  [If that's what you are doing], I would try setting 'black' target at 'minmum' and 'white luminance' at about '120 Cdm2' [as a starting point*].

*You may need to adjust the white luminance target to suit your work room.

It doesn't actually matter what the 'achieved contrast ratio' is reported as [although that does seem to be a weird result], just the appearance when compared against a known printed standard image. 

Try this, the composite image has memory colours so it's pretty obvious if it's way off. 

free test-image download here 

copyright PixlAps & Neil Barstow 2004 / colourmanagement.net (zip file, 1 MB)

http://www.colourmanagement.net/downloads_listing/

As a comparison I suggest you try this software and see how the report comes out

(free 14 day demo - and it works with your i1)

I really like the way it works, you'll need to use a 'manual' workflow : 

https://www.basiccolor.de/products/

[bias alert, yeah we are resellers]

I hope this helps

neil barstow, colourmanagement.net :: adobe forum volunteer

[please do not use the reply button on a message in the thread, only use the one at the top of the page, to maintain chronological order]

[Doc_Pit]

Thanks very much for the help.  I set up two profiles for each monitor: a D55, 100 cd/m2, 1.8 gamma and a D65, 120 cd/m2, 2.2 gamma.  I mainly use the D55 because I'm creating images with the intention of printing.  Really appreciate the help.  Thanks, again.

[NB, colourmanagement net]

Hi

no point forcing a modern display screen to 1.8 gamma,

native gamma is likely 2.2 or close.

Photoshop knows the gamma you used (its read from the profile), so: between 1.8 and 2.2 there should be no visual difference in displayed images.

Of course the desktop area and non colour managed apps will show a difference. 

1.8 gamma was a setting for CRT type screens, its largely obsolete now. 

I hope this helps

neil barstow, colourmanagement.net :: adobe forum volunteer

[please do not use the reply button on a message in the thread, only use the one at the top of the page, to maintain chronological order]

[Doc_Pit]

The D65/120/2.2 profile is substantially brighter than the D55/100/1.8 profile.  My understanding is that the lower brightness and contrast of the D55 profile more realistically represents how an image will appear in print (reflected vs. projected light).  The reasoning, then, is that working with the D55 setting, where the objective is an image for print, makes more sense.  You're saying that's incorrect?  If so, the D55 profile is not useful?

[D Fosse]

What we're all saying is that gamma 1.8 makes no sense. The native gamma of the monitor is close to 2.2.

In a color managed application, gamma (tone response curve) is remapped from source to monitor. Gamma is "invisible". You don't see any difference between gamma 2.2 and 1.8 - but the monitor will behave markedly worse by being forced into non-native behavior.

To get a good screen to print match, you need to carefully set white point to visually match paper white, and black point to visually match maximum ink on that paper. That's how you do it. Gamma has no bearing on that, and it's not a particularly good idea to focus on numbers for the white point. Get it to match paper. Let the numbers fall wherever they want.

[NB, colourmanagement net]

Hi 

"The D65/120/2.2 profile is substantially brighter than the D55/100/1.8 profile.  My understanding is that the lower brightness and contrast of the D55 profile more realistically represents how an image will appear in print (reflected vs. projected light).  The reasoning, then, is that working with the D55 setting, where the objective is an image for print, makes more sense.  You're saying that's incorrect?  If so, the D55 profile is not useful?"

there are crossed wires here

I was discussing gamma not brightness

If you like the brightness setting of 100 Cdm2 and feel it better matches printed work, then that’s fine .

It’s the gamma 1.8 we think is spurious, I suggest you just make the profile again with gamma set to 2.2

I hope this helps

neil barstow, colourmanagement.net :: adobe forum volunteer

[please do not use the reply button on a message in the thread, only use the one at the top of the page, to maintain chronological order]

[Doc_Pit]

Thanks very much. Most of the tutorials I had seen when I started getting into monitor calibration seemed to focus on two options: (1) a calibration for viewing on a screen (D65/120/2.2) and for creating an image to be printed (D50 or D55/100/1.8.). Also, they advise setting "native" contrast. So, I always viewed those as basically THE two options, pretty much set in stone. I never explored a more sophisticated approach, like setting a specific contrast range, or a custom white point or black point. Frankly, I never wanted to have to get that technical. But I can see that there are definite advantages to upping my game here. Again, thanks very much for your help.