Changing the brightness of a calibrated monitor for other uses?

Question

So, in my ongoing goal to start post-processing photos in a color-managed fashion, I've calibrated my monitor using a ColorMunki Display.

However, I have only one monitor that needs to be usable in two situations:

1. everyday use, which includes true work-work and some unimportant editing that I often do with my window open, and
2. serious editing of images destined for my wall or otherwise important, which I do with the window shades down.

The brightness that I need out of the monitor for these two uses is not the same.

The "standard" calibration, with a gamma of 2.2, white point of D65, and luminance of 120cd/m2 is surprisingly bright and may very well work for situation 1, but it is too bright for situation 2.

So here's my question: With a calibrated monitor, is it ok to simply reduce or increase brightness using the monitor's controls (the buttons at the bottom-right)?

This could take two forms, either the calibration is for situation 2 and I manually increase brightness for situation 1, or vice versa, the calibration is for situation 1 and I reduce the brightness for situation 2.

Obviously, I don't want to lose the characterization element, i.e. the color correction for the monitor, from either, but what I don't know is whether or not changing the brightness will mess up the color correction...?

If so, I suppose I could make two .icm files, one at a cd/m2 compatible with situation 1 and another compatible with situation 2, and then switch back and forth at Control Panel>Color Management>Devices, but that seems like a real pain.

I am of course also open to other tactics!

Thanks in advance and happy shooting to all!

KLE-France

EDIT 1: Thanks to all who are participating. The D50 vs D65 debate (and it's a biggy) for printing seems to be coming up.

Two things:

X-rite itself recommends D65, e.g., this, but there are other arguments elsewhere for D65.

And in any case, on my computer, in my "hanging" lighting, and with the printing services I use (which indicates D65), a D65 white point is what works, as does doing my serious editing in a relatively darkened environment with the screen relatively dim.

So, to keep the post from veering off course, and if I may be so bold, my question isn't about D65 vs D50; there are surely plenty of conversations here on that; my question is whether or not manually increasing or decreasing brightness has an effect on the color correction aspect of monitor calibration.

Thanks! KLE

Answer 1

... serious editing of images destined for my wall or otherwise important, which I do with the window shades down.

Part of the entire point of monitor calibration is to equalize, as closely as possible, what you see on screen to what you see in print for the same image. This assumes a well lit environment in which both the monitor and the prints are being viewed. It also requires matching the target monitor characteristics to the ambient lighting present (or, to put it another way, making sure the ambient lighting meets specifications for standard viewing conditions).

Since standard viewing conditions for prints is specified at D50, if your ambient lighting is matched to the D50 standard, then your monitor should also be calibrated for D50 ambient lighting at the appropriate brightness.

There are no real standards for setting a monitor to be used for editing in the dark. But particularly with dim light sources, bluer light sources with higher color temperature (like 6,500K) can cause less than optimal human perception.

... my question is whether or not manually increasing or decreasing brightness has an effect on the color correction aspect of monitor calibration.

As the article about the Kruithof curve linked above indicates, yes it can certainly have an effect, since the same colors at different brightnesses can be perceived as "bluer" when dimmer or "warmer" when brighter by human vision.

Related:
What ambient lighting is appropriate for a room where photos are edited and proofed/printed?
Why don't you need to calibrate a camera's LCD screen?
What's the best light for viewing photos?
What white point temperature should I set my LCD monitor to?
How to select "white point" before calibrating a monitor with Spyder3
What are Color Profiles and where would I find information on using them properly?
What should I consider when designing my physical environment for photo editing?

Answer 2

Well, you can check it yourself.

First, you should certainly calibrate for the critical case, that is, your situation 2. Set the target you like (say, sRGB, 100 cd/m2) and calibrate for it. Then you can try to change (increase) brightness for the less critical situation.

Now simply use your colorimeter to validate the colour profile. I'm not familiar with the ColorMunki software, but all those I used allow to validate (measure the accuracy) of the current colours, without actually correcting them or creating a profile. The device will separate luminance from chromaticity, and will report the measured colour deviation (according to the same selected target, sRGB or whatever). You can then see which way it shifts, and judge if it's acceptable or not.

If your brightness controls change only the backlight, and it's LED, I'd expect the shift to be minimal. But in the end, if it's 'unimportant', why would you care? Just make sure you calibrate for the critical situation, and always return the settings to the original position 'as calibrated' before performing critical work. Maybe your monitor supports 'profiles' of settings and you can use them to switch modes quickly.