Your choice of CMYK working space can be vital for good colour reproduction. In my last post I discussed which RGB working space to use in Photoshop. For RGB there are three common choices competing for your attention, each of which had their pros and cons. For CMYK the situation is a little simpler as there is one very clear winner.
Why is the CMYK Working Space Important?
When you convert a file from RGB to CMYK it is the profiles that you use that determine what CMYK values you get from the RGB data. Using a profile that doesn’t reflect even roughly how the CMYK data will be printed on press could result in poor colour reproduction. CMYK printing presses can use different types of ink, different types of paper, have different tonal reproduction curves (dot gain) and generally print very differently from one another. It is possible to create an ICC profile for a press but they are very variable devices and a better approach is to usually to get the press to conform to a standard rather than profile them individually. It is often the case that a printing company will have several presses and dozens of types of paper in stock so creating so hundreds of profiles and ensuring that the correct one is used to convert the RGB data in a job would become unmanageable. CMYK Working Spaces are usually profiles created from measuring tightly controlled press runs that conform to some national or international standard.
Photoshop CMYK Working Spaces
Photoshop defaults to using U.S. Web Coated (SWOP) v2 as the CMYK working space. The SWOP standard has long been used in the US and so with Adobe being a US company that choice makes sense for North American users. However, printing press standards have moved on significantly in the last few years and profiles based on the ISO 12647 family of standards have become much more common. ISO 12647 defines a whole host of standards for printing including things like standardised inks and papers. More recent US printing conditions often incorporate ISO 12647 standards.
Most customers I find have never changed from the default North American CMYK working space but printing in Europe is historically very different from the USA. In Europe one of the prime movers of the ISO 12647 standard is the German printing standards organisation FOGRA. FOGRA have done many test print runs based on the 12647 standards and have made readings data for those printing runs available including a data set known as FOGRA39L. FOGRA39L is the basis for the very popular ISO Coated v2 ICC profile. FOGRA standards are widely used for proofing and printing in Europe and ISO 12647 is getting wide support from printing companies.
If you select Europe General Purpose 3 or Europe Prepress 3 in Photoshop’s Colour Settings (they are in the Edit menu) then Adobe’s own profile based on FOGRA39L is selected as the CMYK working space. That profile is called Coated FOGRA39. For most European users this is the most logical choice for the CMYK working space. Many printing companies try to conform to the FOGRA or ISO standards and you will generally get better colour reproduction if you supply files in the Coated FOGRA39 colour space, or one of the other profiles based on the 39L dataset. Europe General Purpose 3 would suit a design or advertising agency. The Europe Prepress 3 setting could be more suitable for retouchers, printers and others with a little more colour knowledge. The Adobe manuals and websites contain many good colour management resources to help you decide which setting is best for you.
Supplying Files for Printing
The best colour management tool is not a spectrophotometer, it’s a telephone. If you are supplying images or artwork to a printing company or magazine it will always pay to call them and see in which colour space they would like the data. Many will suggest ISO Coated v2 or Coated FOGRA39. Others will have different international standards that they conform to and have profiles they can send you. A few will still just say CMYK and not know enough about colour management to be more specific. If that is the case then ISO Coated v2/ Coated FOGRA39 would still be the safest choice. You can convert an RGB file to any CMYK profile, not just the comic working space, by using the Convert to Profile option in the Edit menu rather than doing a simple RGB to CMYK mode change, which would use the CMYK working space.
One other factor to think about when supplying CMYK data is the total ink limit. Not many CMYK printing processes can actually print 100% of each colourant without having problems with ink soaking through the paper or not drying on press. There is a version of the ISO Coated v2 profile named ISO Coated v2 300% that limits the ink a little more than the standard profile or Coated FOGRA39 and so it is often used to help bring the total amount of ink down.
CMYK Working Spaces in Other Adobe Software
It is always best practice to replicate your Photoshop colour settings in the rest of the Adobe Creative Suite if you are using other Adobe software. The Europe General Purpose 3 and Europe Prepress 3 are available in InDesign, Acrobat, Illustrator and others. It’s also a very good idea to ensure that all computers in your organisation are all using the same colour settings.
If you use RIP software to process your files before they are printed on your proofer, wide-format printer or press then that RIP will have a setting for CMYK source profile in the queue or media set ups. It’s normally best practice to make sure that the CMYK source profile matches your CMYK working space selection so that you get the closest colour output to the data in your files.
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