Whether you work as a graphic designer, photographer or web developer - ensuring your Mac’s display is accurately representing colours can be the difference between the perfect edit and something that looks washed out! In this tutorial, we’ll explain why your display should be calibrated and the methods to do this.
What is Colour Calibration?
Have you ever printed a photograph or seen a website you’ve created on another computer and noticed that the colours printed look different from those that you saw on your Mac’s display? This can likely be because your Mac’s display isn’t colour calibrated.
What is seen on your display and what the image should look like can be two quite different things
What happened? You’ve changed the cartridges in your printer and it’s been thoroughly cleaned, why are the colours looking a little off? Although the photograph looked great on your Mac, some of the colours looked somehow different on the printed photo - the red looks slightly different, almost purple. The reason for this is that your Mac’s display wasn’t giving you an accurate representation of the colours, only a good approximation.
Why is Calibration Needed?
If you think of your Mac’s display as similar to a home stereo, calibration is just like adjusting the treble or bass. If you just bought a new stereo, you’d spend time adjusting all the different features (such as treble, bass or balance) until you hear what you assume is the best possible sound. Furthermore, as the music will sound different if you’re using large or small speakers in a large room or small room, you must adjust the sound for the space available.
Just like adjusting the treble and bass of your stereo can fine-tune the sound of your favourite band, the same must be done for your display. If you bought a stereo and it came from the factory with the treble and bass turned all the way down, everything would sound terrible! Computer displays aren’t calibrated fully simply because each person will have a different requirement.
Time for a little physics! Light is made up of many different colours - you probably know that white light is actually all the colours of the visible spectrum (the light that we can see). White isn’t actually a colour - it’s a combination of all colours put together. This means that black is the absence of colour.
If you take a look at this colour palette wheel, you’ll see that the centre is white - where all the colours converge
Let’s take two different colour balls - red and black. The red ball appears red because all the different colours of light that make up the visible spectrum is absorbed - all except red. Red is being reflected back and our eyes are detecting this red part of the spectrum. The black ball appears black because all light is absorbed by it - no part of the visible spectrum is being reflected back and so with the absence of any reflected light, we are not seeing any colour. Now imagine if we looked at these same balls under the a blue lightbulb - the red ball would look black because there’s no red light to reflect. The black ball will still look black because it absorbs all colour. It’s this variance of what a light source can be that affects the colours we see on-screen.
Tip: Just as you wouldn’t use a red or blue tinted lightbulb in your work environment, ensure that you have a good lighting source! Energy-saving bulbs can cast a yellow tint to the room so invest in some LED bulbs which are still good energy savers but offers a more neutral white light.
Methods of Calibrating a Display
There’s two methods of calibrating your Mac’s display:
- By eye
- A colour calibrating tool
Before we begin any colour calibration, ensure your Mac is in your preferred work environment and the room is a dark as possible - turn off any lights and close any blinds or curtains. The less outside light we have the better the calibration will be. This is because we don’t have an external light source that could alter our perception of the colour on screen. I’d also recommend setting your desktop background to something dark such as solid black just to avoid any extra eyestrain whilst you’re calibrating your display.
Computer displays aren’t calibrated fully simply because each person will have a different requirement.
To calibrate your display, open up System Preferences and then select Display. You might have a number of them in the list already - if you do, remember which one you currently use and then change it. You’ll instantly see the difference and your Mac will appear to have a coloured tint to it - on my Mac it makes it look like my Mac has a purple tint! However, if I were to take a screenshot and change the profile back, it would look exactly the same - it only affects the output of the display. This is why a photograph can look different than what your Mac shows you.
To calibrate the monitor manually, you can do so using the Calibrate… button which opens up the Display Calibrator Assistant.
The Display Calibrator Assistant
The assistant explains briefly what it does and gives you the option to proceed and calibrate the display.
If you are attempting to calibrate an external 3rd party display, you will be given an additional option to make adjustments before the next step. You’ll be prompted to adjust the display’s contrast and brightness and then fine-tune it.
Calibrator Assistant will prompt you to make adjustments to your display before continuing
Calibrator Assistant will prompt you to adjust the slider to suit your display’s Native Gamma
Gamma is quite a complex characteristic of display calibration. Briefly, gamma is the relationship between how bright a pixel will appear on the screen in relation to its numerical value. It has an affect on the contrast of an image and an incorrect gamma can make images look washed out or we may not see the level of detail in the image as it’s too dark. It’s such a complex subject that it would go beyond the scope of this tutorial. If you’d like to learn more about what precisely Gamma does, you can learn so from the Wikipedia article on the subject.
The option for Gamma 2.2 is the agreed upon standard for what Gamma should be. Older Macs used to use Gamma 1.8 which was the same for the printing industry - this was one of the reasons why Macs were often commonplace in the design industry.
Calibrator Assistant to select target gamma
If you’re calibrating your Mac’s built-in display, Apple already has a good approximation of its Native Gamma and skips the step. However, you can adjust this later in this tutorial.
Setting the white point (sometimes referred to as colour temperature) for your display adjusts the overall tint of the display. The white point scale refers to what appears as white to us, as we actually see many different shades of yellow or blue as white. For example, at the lower end of the scale at around 4100K is the colour temperature of moonlight. If you asked most people what colour is moonlight, they’ll usually say “white”. That’s actually not quite right, we just see it as white but in actual fact it’s slightly yellow - we just can’t tell the difference.
At the higher end of the scale, let’s say 10,000K, this is the colour temperature of a television or computer display. This may appear as white but in fact it’s slightly blue - again, it’s so close we don’t see the difference.
The purpose of the white point is to match your display’s output of white to the white point of what you’re working with - whether it’s printed material or television. If you’re only ever working online and not in print then you can usually leave this to the default setting which is usually 6500K or D65 - on the colour temperature scale it’s known as “middle of the day, overcast”.
Calibrator Assistant to select white point (or colour temperature)
Name your Profile
Once you’ve completed these steps, you will be able to save your adjusted profile.
Calibrator Assistant will let you specify any name you wish
Chances are, you probably won’t notice much of a difference - if any. That’s because with the basic options, there isn’t much to change. Let’s start that again, but with the Expert Mode enabled.
Native Response (Native Gamma)
The following steps are to determine your Mac display’s native gamma. What we’ll be doing is adjusting the brightness and contrast of your display by using a series of sliders.
For each step, the left (brightness) slider should be adjusted until the Apple logo looks almost blended in with the lined background. The second (tint) slider is to adjust the tint of the Apple logo further until it looks almost blended in completely. You will repeat these steps five times to ensure a fully consistent reading. In addition, you can also go back and forth between the sliders if you feel you need to make some further changes.
Calibrator Assistant: Native Response
Calibrator Assistant: Native Response
Calibrator Assistant: Native Response
Calibrator Assistant: Native Response
Calibrator Assistant: Native Response
As you move the sliders, you’ll notice that the tint, brightness and contrast of the screen change. Don’t get distracted by this and focus only on the image.
In this part, we can adjust the gamma to a wider range of values that previously was offered. However, stick to Gamma 2.2 unless you have a very specific need to use another value.
Calibrator Assistant: Target Gamma
Tip: Rather than trying to get exactly 2.2 on the Gamma slider, simply click where it says “2.2” and the slider will automatically jump to that exact value.
Target White Point
You are presented with a wider range of values for the white point but it’s still recommended to use the default values such as D50 or D65 as well as the native white point of your display.
Phew! That seems like a lot to do!
Now, the good news is that once you’ve calibrated the display properly then you wouldn’t need to really change it again unless the working environment (such as new lighting, moved desk) changed. However, even changes to the ambient lighting of the room can be enough to slightly alter our perception of the colour. So what can we do to avoid this?
Thankfully, there’s a number of colour calibrators available on the market. These are small USB devices that will automatically do all of the above work for you and a lot more accurately!
Tip: There are a number of different calibrators out there but not all of them will work with Lion or Mountain Lion - make sure to check the requirements before purchasing!
Devices such as the Spyder4 by Datacolor will cost anywhere between $150-$1000s depending on the features you require. For most users, the lower end of this price range are more than enough and will mean your display is correctly calibrated. Some photography equipment suppliers even rent them out for those on a budget.
The Spyder4 range is a very popular range that works on Mac and PC
How Do Colour Calibrators Work?
Colour calibrators work in a very similar way to how display calibration works when we use our eyes. The calibration tool has a small sensor (called a colorimeter) built-in to it and software that communicates to the device via USB. colour calibrators are so sensitive that they can see discrepancies in the colours displayed that we otherwise would miss. The sensor acts as the software’s “eye” and can determine if the colours on screen are accurate or if the display needs adjusting.
The sensor is placed over the display and colours are displayed, the sensor determining if the outputted colour is accurate and if not, adjusts the profile accordingly
When you run the calibration software, an area will appear on the centre of the display that will be where to place your calibration tool (the calibrators tend to have a number of tiny suction pads to keep it attached). Once placed on the display, you’ll then be advised to turn off and block out any outside light sources. Additionally, you’ll be asked to alter your display’s contrast and brightness since this isn’t controlled by the operating system.
colour calibrators work as software and hardware together
Calibrating the Display
Once the software begins it will display a number of colours on the display where the tool is located - this is why it’s important to place the tool as accurately as possible. After a few minutes, the software checks the results. If the colours need adjusting, it will remember what adjustments are needed and continue.
The calibrator’s software ensures the colours displayed are as accurate as possible
Once the calibration process is completed, you’ll be presented with a new colour profile you can use in OS X. You’ll likely be able to compare what the original profile looked like against the new one before saving the changes.
Tip: It’s always a good idea to check everything looks in order. I had a colour calibration tool develop a fault which meant every calibration I performed had a horrible dark purple tint!
Once you’ve calibrated your display, you’re ready to start editing again! It’s recommended to calibrate your display every few weeks if you rely upon it to be consistently accurate all the time. The colours won’t necessarily change on the screen but your environment might, such as new lightning or even a different time of year where sunlight is less or more.
Most calibration software will provide the option of reminding you to recalibrate your display. For the sake of 10 minutes every few weeks, it’s definitely worth it to keep your display up to date!
If you have multiple displays, you can also use the tool for each display
Which Calibration Tool Should I Get?
This depends on how much you rely upon keeping colours as true as possible. There are some features that the higher end models offer that may be of use. These tend to include features such as more granular controls of settings such as Gamma or colour temperature. All of these sensors will usually work with multiple displays as well - the lower end models usually require a little bit more work.
There’s a number of different companies that provide colour calibrators - I’ve included a list at the end of this tutorial to get you started
One notable feature of higher-end models include ambient light sensors. Your portable Mac or iMac will have an ambient light sensor built-in - this is what controls your keyboard backlight and/or adjusts the brightness of your display when the room gets darker. A calibration tool can include a similar sensor that would adjust the colour profile of your display automatically so that even as the light in the room changes, the sensor will continually adjust the colour profile to keep it as true as possible.
For users who aren’t printing or designing with their Mac, a colour calibration tool isn’t something to consider and manually calibrating your display once in a while will be more than enough.
In this tutorial, we’ve shown you how to calibrate your Mac’s display manually as well as the benefits of an optional colour calibration tool. If you rely upon colours being as true as possible, a colour calibration tool should be an essential piece of equipment in your workflow and are extremely inexpensive when compared to the problems it will avoid for you.