I’m starting to get into all my back to school routines this week, one if which is monitor calibration. At school I edit on my Macbook Pro but at home I usually just use my desktop monitor. So for most of the summer, and most of the time that I’m home, I don’t edit using my laptop’s display. I figured this week would be as good as any to calibrate my laptop screen again since I haven’t used it in a while and I ran into a couple of things which I’ll explain in a minute.
I’d just like to pause here and quickly explain for those of you that are unaware about calibrating your display. A computer monitor fresh out of the box will probably look great to the naked eye (which is why you bought it). The colors may look fine to you but they’re probably not even close to accurate when referenced against targets built into calibration software. Now, you could say, “Well I can just eyeball it right?” No, your eyes are not to be trusted AT ALL for “eyeballing” the color on your display. When you walk into a dark room from outside notice how your eyes adjust so that everything doesn’t look dark anymore? Or if you light a candle in a room, the room doesn’t seem that yellow/red but it is a lot more yellow/red than you realize. Your eyes adjust to whatever environment you’re in so it’s important to use some hardware/software combination to calibrate your monitor for you and ensure you are getting accurate color on screen. Initially it may look wrong or broken to you but that’s just because you’re used to looking at an uncalibrated display and often the first calibration is a big jump in the right direction. Anyway, buy a colorimeter from Datacolor (Spyder Series), or X-Rite (Colormunki/ i1 Display) and thank me later. They all do roughly the same thing so you have some options.
If you do some googling or talk to most any visual artist they’ll tell you that editing on a laptop screen is probably the worst type of display you could do any color critical work on. A lot of this has to do with the laptop display’s ability (or any display’s ability) to represent the full gamut of colors present in different color spaces. Most notably, AdobeRGB and sRGB color spaces. We’re not going to get into color spaces today because I think most people, most displays, and most printed work hasn’t suffered much from not being able to showoff the entire AdobeRGB color gamut.
I’ve never heard anyone print out one of their photos and say something like, “Crap, this picture doesn’t have as many colors from the AdobeRGB color gamut as I wish it had.” Depending on the picture it’s likely that it wouldn’t have a full rainbow of colors in it unless the picture was actually a rainbow or something. If you notice any BIG color discrepancies between your image on screen and your printed image it probably has something to do with using the correct ICC profile for your printer, paper and ink about 9/10 times. Again, this is another topic for a different day but I wanted to mention it because a lot of people will attribute a problem to the wrong thing. I’m saying that creating accurate color on a laptop display is a lot easier and more obvious than all of those things.
Realistically, the big downfall of laptop displays and the software that calibrates them is that the brightness (Luminance) is variable. You can always change the brightness of your laptop screen at the push of a button which you probably wouldn’t do nearly as often on a desktop display. Brightness on any display is measured by candela per square metre (cd/m2) which is the International System of Unit’s unit of measurement for Luminance.
As a rule of thumb most monitor calibration devices will recommend a brightness setting of about 120 cd/m2 to start. This is based off the International Standard: ISO 12646:2004 Graphic technology – Displays for colour proofing – Characteristics and viewing conditions which states, “The chromaticity of the display should be set to D50. The luminance level should be as high as practical but shall be at least 80cd/m2 and should be at least 120cd/m2. The black point shall have a luminance that is less than 1% of the maximum luminance.” which I found for reference here instead of purchasing myself a copy. Also you should take into account the lighting conditions of the room you are working in. Editing outside in broad daylight or near a bright window isn’t a good idea. Usually just having a low light setting is good, but again, it depends. If you really want to get picky you could work in a room that’s completely painted floor to ceiling in 18% gray reflectance paint with no windows and only wear black or gray clothes when you’re editing. This is the real world though and you’d probably want to kill yourself before doing any of that.
Ok, so the next big question here is “How do I get my laptop to calibrate specifically to 120 cd/m2?” The answer being, for example with my Datacolor SpyderPRO 3 software, is simply to change the default brightness target from the Laptop preset which is whatever the native laptop brightness is (this is what we don’t want because there’s no way to measure this against a target unit of brightness in the software) and change it to the standard LCD preset which is 120 cd/m2.
So now during your laptop’s calibration sequence (For this example in the SpyderPRO 3 software) it will pause at one point to allow you to change your brightness and match it as closely as possible to 120 cd/m2. If you’ve calibrated a desktop monitor before you’ve run into this step in the process where it makes you change the monitor brightness to match the target. This might be different in other software.
For some reason in the SpyderPRO 3 software it recommends that you use the native laptop brightness when really it should treat your laptop screen just like standard desktop LCD and calibrate to the industry standard brightness. I’m recommending that you do whatever you have to do in your software to make sure that you calibrate to 120 cd/m2 and make sure it stays that way. It’s also a good idea to recalibrate every week or two after your monitors warm up for fifteen minutes.
Just before I did this whole process my laptop brightness was set to half brightness (which was WAY under the 120 cd/m2 target at around 40 cd/m2) and there was a big difference between my laptop screen’s brightness and color VS. my desktop monitor which was already at 120 cd/m2. This hasn’t been a problem for me until now because I have only used my desktop monitor all summer but now that I’ve recalibrated both displays to 120 cd/m2 they are extremely close to each other if I use a picture for reference on both displays.
Now that your laptop is all calibrated and the brightness is set correctly you should probably make sure that you don’t accidentally change the brightness and screw up your calibration. I found that 120cd/m2 was not directly on one of the bubbles on the mac brightness and I had to change it in the System Prefs. Still though you could hit the brightness options on your keyboard, so how do you avoid doing that?
I wanted to find a program or something that would take a sort of screen shot of my laptop screen brightness so that I could come back to it if I ever had to change it, but I didn’t really find much. I did however, find this little program called “Function Flip” what this allows you to do is to instead of disabling all the brightness/volume F-keys like you can in the System Preferences on the Mac, Function Flip allows you to selectively turn some of your F-keys back to just F-keys and not a brightness adjustment. So it should look like this:
Now I won’t accidentally change my monitor brightness from bumping the brightness key on my keyboard. You can also set it to start up at Login so you don’t have to try and remember every time.
This is kind of a bush-league way of keeping track of your brightness but I just screen shotted it in the system preferences so that I at least have a picture to reference roughly where my brightness is should I ever actually need to change it and can’t recalibrate that same day.
Anyway, that’s about it. I’m kind of boggled I didn’t pick up on this earlier. Don’t set your laptop brightness to some arbitrary brightness, try and set it to an international standard of 120cd/m2 and watch your room’s lighting conditions and you’ll be fine.
See you next time
Looks like I’ll be writing about ICC profiles, soft-proofing and color gamuts in a couple future posts because I also ran into some stuff with that recently that you might be interested in reading about.