Calibration and Profiling – not the same thing

The difference between calibration and profiling in colour management

Red bus in Leicester

A well known colour red

The other day I saw someone mention a ‘printer calibrated to their monitor’. I’d noticed  elsewhere that there is a deal of confusion in the terms calibration and profiling, which tend to get used in an imprecise way. This short note is just aimed at this point, and is part of many more related articles and reviews on the site, all indexed through our Colour management page.

The person using the phrase was using a ColorMunki (presumably for their monitor and printer) so was obviously interested in getting the best from their monitor and prints.

I’d note that the terms ‘calibrated’ and ‘profile’ seem to have a range of other meanings in parts of the print industry, dating back many years. I’m specifically talking here about usage of the terms in an ICC based colour managed workflow for photographers, who might capture/scan/edit their own work and print it themselves or send it off to an external printer. These people are the primary intended audience for the reviews and articles on this site. Just be aware of the wider fluidity of these terms, and if someone uses one in an unfamiliar way, just ask what they really mean?

So… the difference

Colour management (including for Black and White) is essentially about knowing the characteristics of devices (profiling) and setting devices to known standards (calibration).

You might calibrate a display to a 6500K white point and known luminance (say 120 cd/m²), whilst the monitor’s profile describes what output colours it produces compared to what it is sent. Think of it as a way of knowing what actual colour comes from the screen when you send it a particular value for a pixel. An RGB value of 255,0,0 is red, but what red? Looking at this the other way round, it tells me what numbers I need to send to display a particular red. It also tells me if the red I want to display is actually capable of being displayed on this particular device.

Profiling a printer

Profiling a printer

For a printer, you don’t calibrate in most cases – when you hear the use of the word calibration in connection with a printer, there is a distinct chance it is wrong. For printers, calibration is generally something that happens at the factory, and in the case of smaller printers, only at the factory. It is improvements in calibration and manufacturing that make ‘canned’ printer profiles a lot more useful than only 10 years ago.

I’d note that some printer manufacturers’ software and specialist printer driver software may exist for a printer, to calibrate the printer to a known factory state, but the process most people will be familiar with is printer profiling, which once again is a way of describing the printer’s output for a given input.

When I replaced a printhead on our large format printer recently, I ran a calibration process on the printer, to bring its characteristics to a factory standard. This means that I don’t have to create new printer profiles after changing a print head.

Profiling a camera

Profiling a camera: X-rite cc passport

Profiles are about converting colour data from one representation to another. Fortunately, all the messy maths are taken care of by the colour management parts of your applications and operating system. Printer profiles are what can enable predictable print output and soft proofing.

You can produce custom profiles for a camera, although they are already there inside your camera (for jpegs) or RAW converter.  Camera calibration is something carried out at a service centre.

I’m probably guilty myself, of occasional imprecise usage of the words when talking about monitor calibrators, such as the Spyder 4 Elite or i1Display Pro  I’ve reviewed . However I do try and keep the meanings clear.

I’ll finish with the definitions from the book I most often recommend (Real World Color Management)

Calibration
Modifying or adjusting the behaviour of a device (such as a colour reproduction device or colour measurement instrument) to a desired state (often a factory specification, or some state that simulates another device).

Profile
A file that contains enough information to let a CMS convert colours into or out of a specific colour space. This may be a device’s colour space – in which case we would call it a device profile, with subcategories input profile, output profile and display profile (for input, output and display devices respectively); or an abstract colour space such as a working space, such like Adobe98

…and since I mentioned it
CMS
Colour Management System. Software dedicated to handling device-to-device conversion of colours. The ICC based model for a CMS consists of four components: a PCS, Device profiles, a CMM, and a set of rendering intents.

For details – read the book. My copy lives on a bookshelf just a few feet from where I’m sitting…

Real World Color Management 2nd Edition
Real World Color Management 2nd Edition