Monitor calibration, how, how often?

[Colin Southern]

BTW the biggest adjustment you need to make with the iMac is luminance. In the stores they are displayed way too bright: luminance is far too high. If you're looking to match print and screen, depending on your office lighting which will determine the 'brightness' of prints, you'll typically need to dial the iMac luminance back to ~100 cdm2.

I always find luminance to be a judgement call; if you're in a subdued ambient light area then 100 is good, but I like to work in a reasonable brightly lit environment, and actually run mine at 200 cd/m2.

[Downrigger]

Thanks, Colin, and Tim. I can see that luminance is important if you want the appearance on your screen to accurately predict the lightness and values you would expect from a print. My macBook Pro (Retina) has a slider for luminance in "settings"-"display" but I can't figure out how to read or set the actual value it is at in cd/m2... it is just a relative adjustment, without values for luminance as near as I can tell.

[Colin Southern]

Thanks, Colin, and Tim. I can see that luminance is important if you want the appearance on your screen to accurately predict the lightness and values you would expect from a print. My macBook Pro (Retina) has a slider for luminance in "settings"-"display" but I can't figure out how to read or set the actual value it is at in cd/m2... it is just a relative adjustment, without values for luminance as near as I can tell.

In terms of predicting what a print may look like, it's 1/2 of the battle -- but prints and monitors usually have pretty big dynamic range differences, which complicate things (things like shadow detail visible on a monitor can get crushed in a print). Generally though, it's the levels you want to get right -- most don't notice small colour shifts (many don't even notice huge ones it seems!), but levels are what separates pro-quality work from amatuer stuff more than anything else in my opinion.

With regards to cd/m2 ... the Spyder Colorimeter gives a readout in the software. That - alone with white balance - are the only 2 things I bother calibrating on my monitors ... everything else I just leave up to the profile.

[Mike Buckley]

With regards to cd/m2 ... the Spyder Colorimeter gives a readout in the software.

You're probably referring either to the Elite or Pro version, as the lightweight Express version does not include that capability.

[ajohnw]

You're probably referring either to the Elite or Pro version, as the lightweight Express version does not include that capability.

Check but I'm pretty sure that even the light weight colormunki does this. TV's and projectors too - but again check.

There is a lot of information and good reviews on this site.

http://www.northlight-images.co.uk/reviews.html

When I read threads like this I always wonder how far people go. I did consider changing to broad spectrum daylight lighting but decided to give it a miss.

John
-

[Colin Southern]

You're probably referring either to the Elite or Pro version, as the lightweight Express version does not include that capability.

You could be right. It's just one of the steps included in the wizard, but it does depend on what options you tell the software is available on the monitor.

[Macmahon]

Thanks, Colin, and Tim. I can see that luminance is important if you want the appearance on your screen to accurately predict the lightness and values you would expect from a print. My macBook Pro (Retina) has a slider for luminance in "settings"-"display" but I can't figure out how to read or set the actual value it is at in cd/m2... it is just a relative adjustment, without values for luminance as near as I can tell.

Mark
The absolute cd/m2 value doesn't matter a whole lot. The right value, as Colin says, depends on your local lighting conditions. IOW it is relative. To get in the ballpark with your sliders, the simplest thing to do to control just the luminance bit of the job, is to make you monitor screen white (display something like a blank word-processing page on full screen) and take a piece of photo inkjet paper and set it alongside your computer, in the position you would tend to want to look at a comparative print. Now eyeball the screen then eyeball the paper. Adjust the screen brightness slider until, as far as you can tell, the brightness of the screen is about the same as the reflected brightness of the paper.
That will be a good place from which to start a decent profile measurement.
Does that help?
Tim

[davidedric]

To confirm John's comment, the ColorMunki does measure ambient light before profiling and calibrating. It also has the option to continue to monitor ambient light, though personally I don't do this because the level changes very little.

[ajohnw]

Mark
The absolute cd/m2 value doesn't matter a whole lot. The right value, as Colin says, depends on your local lighting conditions. IOW it is relative. To get in the ballpark with your sliders, the simplest thing to do to control just the luminance bit of the job, is to make you monitor screen white (display something like a blank word-processing page on full screen) and take a piece of photo inkjet paper and set it alongside your computer, in the position you would tend to want to look at a comparative print. Now eyeball the screen then eyeball the paper. Adjust the screen brightness slider until, as far as you can tell, the brightness of the screen is about the same as the reflected brightness of the paper.
That will be a good place from which to start a decent profile measurement.
Does that help?
Tim

In some ways the illumination of the screen does matter. If you look on the UK tftcentral site you will find he provides basic brightness and contrast settings suitable for best calibration of the monitors he reviews. I have heard from others that these figures can be shifted but there are limits for a good calibration. Some people just use the icc profiles he generated for each one he has looked at.

If your calibrator doesn't come with some sort of diffuser measuring ambient light levels is a problem. Another reason I went for a colormunki. I am unsure how much ambient lighting colour temperature may mess this aspect up though. I was concerned about that due to the measured values and added an extra light but found it made little or no difference. I assume my eyes balance to the screen even though the ambient is well off. The main lighting is up and behind the screen so the fact that it is diffuse may help with that aspect.

After using the software that comes with a calibrator people who don't own an excruciatingly expensive spectrometer might like to try this software and see what it reckons. Some people who do own them use it as well.

http://dispcalgui.hoech.net/#concept

The trick to getting the best possible calibration is to achieve an exact balance on the colour bars that come up initially to set the r g b levels controls in the monitor.

Whoops - also allow it to correct for the fact that LCD type monitors do not produce a true black. There is always a little light there. Perhaps local dimming monitors don't do this but I find it hard to believe that this works perfectly unless it's done at a pixel level.

John
-

[ajohnw]

To confirm John's comment, the ColorMunki does measure ambient light before profiling and calibrating. It also has the option to continue to monitor ambient light, though personally I don't do this because the level changes very little.

The one I have is the Display. Just checked having seen a comment that some calibrators are not temperature compensated. I haven't seen anything that would suggest this is a problem but do leave everything on for some time before using it.

On using the software I mentioned I too get confused by terms. It will run 2 routines. One quick which determines the colour ordinates and gamma. This is just intended to check if things have drifted far enough to justify a new ICC file - that's the other. It has 2 varieties one of which uses a lot more colour patches. After running that it gives options to install the icc file for you if needed. They are saved anyway so it's best to give some thought to naming them. In my case I install system wide. Some applications need it installed in them as well.

John
-