Screen calibration with different luminance values

[Eigil Skovgaard]

Hi,
I use ACR and Photoshop for my editing.
Lately I upgraded my screen and calibrated it to the general standard 120 cd/m2, 6500 K and gamma 2.2.
The value 120 cd/m2 from a larger screen made it a bit harder to look at the screen for hours. So I began wondering why this value, 120 cd/m2, has been chosen as a common standard - AND if it would harm my images if I used e.g. 90 cd/m2 while others would still look at them at 120 cd/m2 (?)

This is my thought experiment:

If I select the value 254 for a highlight in a specific image with my screen calibrated to 120 cd/m2, I'll have to push the exposure slider to the value e.
If I do the same with my screen calibrated to 90 cd/m2 I'll need to push the exposure slider to e+g to reach the value 254 for the same highlight.

So, for the same image I'll end up with two xmp files with different exposure values.

Question:
Will those two images look identical on a screen calibrated to 120 cd/m2 - or will the e+g version now show 255+ in the highlights ???

[Doug Nelson]

This is out of my area, sorry. Let's hope Chris Tarantino is around. He's your man for that kind of thing.

[Eigil Skovgaard]

Then I am looking forward to Chris Tarantino coming around. Is their any way to accelerate that happening - e.g. by forwarding a link to him?

[Doug Nelson]

Not really. You can try messaging him here if he has that enabled (click on his name in any forum post), but I don't think it would be appropriate for me to do it.

[Chris_N]

Out of interest, What hardware device did you use to calibrate your screen? You could contact their support team (eg Datacolor) for advice.

I am not qualified to explain exactly how the calibration system works but here are a few personal thoughts about monitors and calibration. Please can someone correct me if I have made any mistakes.

1- Go to the Lagom test images and see if you can see all the tones on your monitor. In particular, check the Quick contrast test, Gamma, black level and white saturation. If you can't see everything then try turning off the lights in your room.

http://www.lagom.nl/lcd-test/

2- Download some printer test images and see if they look decent on your screen. They should not need any editing to look good. Compare if that's how you would have edited them with the same brightness.

https://www.northlight-images.co.uk/printer-test-images/

3- Editing software like Lightroom works off the file histogram and not what your screen displays. So it will show the warning dialogues regardless of how your screen is set. You will be able to set your black point and white point accurately. If your monitor gamma has been set correctly, this will allow you to adjust your midtones and exposure more accurately. With experience Your eye can adjust to your particular setup.

4- I believe 120 cd/m2 is a matter of taste but it is chosen so as to get a decent screen to print match. If for example you work in a brightly lit room and use 180 cd/m2 the image will look brighter on your screen but will print darker "compared" to your screen. So 120 cd/m2 will give you a better guide as to how the print will look and getting it right the first time. But there is nothing wrong with having your screen set to a different level.

5- Looking at a monitor is somewhat subjective. Sometimes I have edited an image in the evening and think its just right. Then tomorrow morning I think its too bright or too dark. Maybe I was just too tired or was staring at the screen too long. Or maybe the ambient light in the room threw me off. A low end monitor will not show the complete Adobe RGB colour space anyway. It also depends on how much ambient light is in your room. With experience your eye and brain learn how to "read" the image. Keep a note of the histogram while editing. So if someone works in a bright room and has learned to "read" his monitor set to 180 cd/m2, with experience he should be able to edit the same way as someone with a monitor calibrated to 120 cd/m2 or 90 cd/m2.


Kind regards
Chris

(Chris the Forum Newbie - Not Chris Tarantino)

[rossjaco]

This is informative Chris!