Colour management

And so to Fedrigoni Paper on Clarkenwell Road to attend a presentation on colour management by designer Andy Brown and colour consultant Paul Sherfield of the Missing Horse Consultancy

The Print Handbook

Andy is the author of The Print Handbook, a pocket guide to help designers get the best from their print projects, and I’d met Paul a couple of years ago when he was contracted by COI to help improve our studio colour management.

As the responsibility of pre-press has shifted from printers to the design studio, creatives find themselves required to colour manage their open or PDFX output files, but have little idea of how to work within a structured colour-managed environment. Paul’s mission is to help designers improve their pre-press workflow by explaining the benefits of colour management policy, where it is needed and how it is applied.

Colour management provides a unified environment for handling colours, where a common colour reference is used at each step of production, from photography through design, plate making and printing.

It aims to unify the image throughout the entire production process by using the profiles of the various devices to manage colours.

Comparison of some RGB and CMYK colour gamuts

Basically, you have two colour gamuts, RGB for optical devices and CMYK for output devices. RGB has a wider gamut, whilst CMYK ‘clips’ the available colours into a space that can be rendered by an output device.

However, neither is an absolute – both RGB and CMYK gamuts are device dependent, so the space you work in depends entirely on the input device and the intended output device.

Problems of colour perception also arise because the designer is looking at a monitor that generates colour in RGB, a local colour proof is typically produced in CMYK on an inkjet printer (which deposits ink on the surface of the paper), whilst the commercial printing process (which is also working in CMYK) presses ink into the substrate. (Printed material reflects light, so colors also look different depending on the lighting environment!).

To achieve the best colour fidelity, you therefore need to align your input, editing and output devices, from camera through to press, so they are all working in a common colourspace (independent of any device) so that the various colours can match as closely as possible. This is the basic principle of colour management.

Translation between devices is achieved using International Colour Consortium (ICC) profiles. Based on Apple’s ColorSync engine, ICC profiles are the accepted means of maintaining the consistency of colour files when transporting them between the originator/creator, publisher and printer.

The ICC profiles manage colour between different devices, ensuring that the correct rendering intent is maintained.

The standard rendering intent for printing in North America and Europe is the Relative Colorimetric method. This compares the extreme highlight of the source colourspace to that of the destination colourspace, and shifts all colours accordingly. Out-of-gamut colours are shifted to the closest reproducible colour in the destination colourspace.

So how do you go about setting up a colour-managed environment?

Working backwards from your commercial printer, find out what colour profile your printer is using for the intended press and paper stock, and ask how they would prefer your open or PDFX files set up.

Outputting to a PDFX format retains your embedded colour profile so that your printer knows the colour intent.

For example, in the UK most printers working to ISO 12647/2 will use Adobes ‘Coated FOGRA39 (ISO 12647-2-2004)’ profile which is in the later versions of Adobe CS and used by their colour settings file ‘Europe Prepress 3’. Colour profiles created in this way will prove to be repeatable and maintain their colour fidelity for both litho and digital presses - and are therefore preferable to custom profiles.

Your local proofing device should be set up to use the same profile.

In Adobe Bridge, set your CS colour settings to ‘Europe Prepress 3’.

Calibrate your monitor into the same working space – although note that as monitors warm up, the perceptual colour will change slightly, so for colour-critical work, monitors should be re-calibrated at regular intervals.

Finally, ensure that all images have an ICC profile embedded – if not, then a generic RGB colourspace, such as sRGB or Adobe RGB (1988), will be assigned when the file is first opened or imported. (If you open a document embedded with a colour profile that doesn’t match the working space profile, in most cases, the best option is to preserve the embedded profile because it provides consistent colour management.)

sRGB is recommended when you prepare images for the web, because it defines the colour space of the standard monitor used to view images on the web.

Adobe RGB is recommended when you prepare documents for print, because the Adobe RGB gamut includes some printable colours (cyans and blues in particular) that can’t be defined using sRGB.

So having aligned the colour profiles of all the devices in your workflow, you can design in in a colour-controlled environment, knowing that what you see really is what you’re going to get.