Display Calibration For Viewing On Displays / Devices

Question

I am using an Xrite ColorMunki Display to profile my displays. As part of the calibration process, I need to choose the White Luminace for my display (an iMac Retina 5K). I can either ask the ColorMunki to measure the ambient lighting and automatically set the whitepoint for best screen-to-print matching:

I would like ColorMunki to automatically determine the optimum luminance level fro my display based on my ambient light conditions where I view my printed output. (Recommended for display to print matching.)

Or I can choose from a series of predefined display luminace values (cd/m2).

• 80
• 90
• 100
• 110
• 120
• 130
• 140
• Native

I understand that I can place the ColorMunki in my print viewing area with my viewing light on and have it measure the light there and build the profile accordingly. However what about when I know the image will be viewed on a screen? I can understand that measuring the ambient lighting in my room could help tweak the profile so that the way I perceive the image is minimally effected by the strength of light in my room, but obviously every screen / device and every environment in which they are used will be different (compare someone viewing using an iPad on the beach to someone on a laptop in a dark bar). The auto option even says 'Recommended for display to print matching', so I'm assuming I should instead choose one of the fixed values.

So what should my display luminance be set to if I want to preview images destined to be viewed on screens / devices?

Note: I'm setting my Whitepoint to D65

Answer 1

I know that I cannot control other people's screens, but that is part of the question - if I cannot know the final circumstances of viewing, then what should guide my choice?

The ISO standard for viewing prints and for viewing images on a monitor is what should guide your choice. The best you can hope for is that the viewer of your images have also created a viewing environment that complies with the same standard.

The standard for viewing photos on a monitor is D50 (broad spectrum light with all of the components, including UV, carefully controlled and centered on 5000K). For LCD monitors the intensity of the ambient light as measured at the center of the screen should be 55 Lux. The monitor should also be calibrated to D50. Recommended maximum (pure white) brightness with an LCD monitor is 120 cd/m². For a CRT it is 100 cd/m².¹

There are many in the graphics industry that prefer to use D65, which is centered on 6500K, for monitors. This is perfectly acceptable as long as the monitor and the ambient lighting match. However, care must be taken not to allow the 6500K ambient light to affect the perception of the D50 light source illuminating prints in your print viewing booth (D50 is the standard for viewing prints). In the case of a small print viewing box, you would need to turn off any non D50 lighting when critically evaluating photo prints. Otherwise you risk metameric failure.

Metamerism is when two objects render different spectral power distributions yet visually match under a certain lighting/viewing condition, but not under another. Two objects that visually match under at least one lighting condition are called a metameric pair. When two objects match under one light source/viewing condition but not under another, the resulting condition is called metameric failure.

If you print match under D65 lighting you risk the color not being perceived as the same under D50 standard lighting conditions.

_{¹ "Maximum" in this context is what the calibrated monitor is measured at when displaying a pure white signal (e.g. [255,255,255]), not what the monitor is measured at when the brightness is turned all the way to 100%. Minimum is what the monitor is measured at when (attempting to) display pure black (e.g. [0,0,0]). Maximum at 120 cd/mm² is the correct brightness assuming the monitor is showing pure white when it is measured.}

Answer 2

Hum You are mixing diferent things here.

Determine your white point. This is not the same as intensity.

Ambient Light and ambient background

Ambient light behind your monitor is a relative thing. Imagine you have a lamp above your desk, but all your things, desk, wall, coffe mug, are painted matt black. The sensor could pick the ambient light as the recoved by the lamp but has nothing to do with the actual background you have behind your monitor.

A quote from here: https://www.just-normlicht.de/en/iso-3664-2009-01.html

Colors in the area surrounding the viewing surface affect perception, which is why the standard prescribes neutral-gray, low-reflection ambient conditions. Be it a booth or room walls, the reflectance of the coating of the viewing environment is set at a maximum of 60%. Unless otherwise stated, JUST standardized viewing booths and stations are coated in neutral gray according to Munsell N7, which meets exactly these requirements.

The problem is that this states for the printed samples, but you could adapt this to your environment behind the monitor. Remove wood finishes (warm color) or distracting elements.

Put a light source of the same temperature of the white point you defined in your workflow.

Adjust the distance of your environmental light so, when projected to the background it gives not more than that 60% compared to the monitor. Measure the reflected light not the incidental light.

(A bright background of about this 60% actually could stress your eyes less than a dark one)

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One thing you might need to consider is that if you are not using a viewing booth, you might be tempted to compare a printed sample next to your monitor, just try to balance this two situations, try that the viewing light does not cast too much light into your monitor. A shield either the viewing boot or the monitor could be a good option.

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You can NEVER control a viewing condition on the user's screens. So stop worrying that.

One joke I once comented:

A drunk man is driving on a highway and listen on the radio: "one driver is on the wrong way of the highway" And he says... one? There are a lot of them!

The point of calibrating your monitor is just to be sure you are not the drunk man.

Answer 3

It depends on whether you insist on print matching or not. Print matching does not necessarily give the best results for displaying on the web.

Matching to print viewing area requires that your monitor is set to lower white point and probably lower brightness. Some displays handle that better than others. If you go too far from the native values of the display, the higher the probability that you start experiencing issues like uneven gradients or loss of shadow detail. Your display may be perfectly fine, but it does not hurt to check quality of your profile... See here and here and especially here.

My pictures are sometimes printed, but mostly displayed on the web. I don't have a print viewing booth, my print viewing area is just a desk lit with Solux lamps. When I calibrate, I pick luminance around 100 and auto-adjust prints using the Print Adjustments feature in Lightroom. It gives good results on both my Epson 3600 and the web including mobile devices.

Your question has changed, but if you are asking what values you should set, pick brightness around 100 - 120, white point D65 and check/tweak you profile using the links above.