An Introduction to Calibration and Device Profiling

Paul Lindström discusses the benefits of ICC technology and the ability to preview colours in your artwork  as they will appear in the final print, which will help avoid colour errors, reduce waste, save time, money and stress. 

It’s now 25 years since the International Color Consortium (ICC) was formed and the ICC colour management technology introduced. The ICC started as a joint effort between Adobe, Agfa, Apple, Kodak and Microsoft. Their idea was that colour management should be done starting at the computer operating system level, and that all applications should do it in the same way. This would add both consistency and ease of use.

The ICC invented a standard file format for colour conversions: profiles. The ICC’s colour scientists also decided that colours should be defined neither in CMYK (Cyan, Magenta, Yellow and black, called K because it’s the Key colour) nor RGB (Red, Green, Blue) colour spaces, because doing so limits what can be done with the colour data. Instead the ICC technology is based on the CIE Lab and CIE XYZ colour spaces which are much larger. These colour spaces are collections of mathematical definitions of all the colours humans can perceive, which is way more than either CMYK or RGB can represent.

Why a device independent colour space?

Lighting up

Colour conversions

To make a colour conversion from for example RGB to a print specific combination of CMYK, you need to know or specify what type of RGB your image is referring to, as well as the correct ICC profile for your print production. Adobe RGB and sRGB are among the most popular for photos, but you need to know which one has been applied to your images in order to handle the conversions correctly.
Caption: In ICC technology the reference colour space is not RGB or CMYK, but a device independent colour space, CIE Lab, as shown here. Redish colours have positive a values, yellow positive b values, greens negative a values and blues negative b values. But you don’t necessarily need to know this to use ICC profiles.

What devices do I need to calibrate?

 As a designer you must calibrate your monitor, if you want to see colour accurate artwork and images. For this you will need a colorimeter or spectrophotometer. If you buy a high end proofing monitor – which we recommend because you can’t really calibrate cheap standard monitors properly – the manufacturer will provide dedicated software for calibrating it. The monitor software will also support the most commonly used colorimeters and spectrophotometers. In the process of calibrating your monitor, you will create a unique ICC profile for it. This ICC profile will define the colour characteristics of your monitor as it is setup by you. Inside the ICC profile is a table mapping how the monitor’s RGB values correspond to values in CIE Lab, and how they will be used by the colour management system to display colours correctly.
Caption: All apps compatible with the ICC technology support both soft- and hardcopy colour accurate proofing by applying the relevant ICC profile for the printed job. Here an example from Adobe Photoshop, where the popular Fogra 30 ICC profile is used for prints made to be compliant with ISO 12647-2 (Process control for the production of half-tone colour separations, proof and production prints -- Part 2: Offset lithographic processes).

Colour accurate proofs

How do I do softcopy proofing?

How do I do hardcopy proofing?

Spot the difference

The ICC technology only provides good colour management for working in either RGB, CMYK or greyscale (black and white). While you can call for spot colours in your designs, they are not very well displayed, or colour managed unless you use a special application such as the tools EFI provides as part of its Color Profiler Suite. There are developments underway to improve colour management for spot colours in the latest version of ICC’s technology, but either way you must learn to properly colour manage RGB and CMYK in your processes to get the best results.

By learning about and applying ICC technology you can preview colours in your artwork as they will appear in the final print. This will help you avoid colour errors and so reduce waste and disappointments. It will also save time, expense and stress, so build up your knowledge and experience to master it and give yourself a value-added edge.

The Wild Format guides are intended to expand awareness and understanding of the craziness that can be created on wide format digital printing devices, from floors to lampshades and everything in between. These guides are made possible by a group of manufacturers working together with Digital Dots. This article is supported by Digital Dots, EFI, Fujifilm and HP.

FESPA’s new colour management feature, COLOUR L*A*B* will be introduced for the first time at Global Print Expo 2019 in Munich. It is aimed at helping visitors improve colour management practices in their own print businesses. The feature provides a walk-through showcase of representative technologies from a range of specialist suppliers, live demonstrations, guided tours of the exhibit, and educational presentations from subject matter experts. Book your tour now and discover the steps and technology to achieve consistent colour throughout your production mix.