This is a question we’re asked regularly and it causes some confusion. Images are generally captured using the RGB colour mode but, for printing, they need to be defined as CMYK mode. Think of it as the difference between screen viewing and printing.
The initials RGB represent the primary colours of the screen mode – Red, Green and Blue, CMYK represents the primary colours of printing – Cyan, Magenta, Yellow and Black (Black being represented as K or the Key colour).
In the early days of desktop publishing, images were converted to CMYK using Photoshop before they were placed into a design application like Illustrator, QuarkXPress or InDesign. This process can be time consuming and creates a variety of inconvenient side-effects. The CMYK colour mode is adapted for specific printing processes and machinery and has a reduced colour range compared to RGB so CMYK images so are not suitable for reuse in many other media. A further benefit from leaving images as RGB is that much of Photoshop only works in RGB mode so, if you convert an image you’ll find a substantial amount of Photoshop’s editing capabilities are disabled.
The good news is, this process is no longer necessary, as long as you are exporting your document to a PDF using a preset which includes a colour conversion.
Let’s explain that further. The typical way to change colour modes in Photoshop is to manually select Image>Mode>CMYK Color, however, as all Adobe applications use the same colour engine, you can perform an RGB to CYMK conversion at any point in your workflow using any Adobe application. If you are sending print-ready PDF’s to your print provider, you can automate the conversion by placing RGB images into InDesign or Illustrator and creating a PDF using choosing a preset such as PDF/X-1a2001 or Press Quality. These presets contain a built-in conversion which will convert any images to CMYK automatically. The original pictures will remain untouched, leaving you free to reuse them for output in other media without making duplicates.
This does not automate creative processes such as colour correction, retouching or sharpening and these should be carried out in Photoshop in conjunction the various soft proofing tools such as Proof Colours and Gamut Warning.
In cases where you intend to send open InDesign files and links to your print provider this approach is not suitable (unless you’ve agreed that your print provider will perform the conversion). For most people, however, converting on export to PDF offers a much quicker and more efficient way to ensure images are correctly adjusted for print.
To learn more about working with colour with Creative Cloud, contact us.