What is the best colour space to design in – RGB or CMYK?

I’m happy to help. It’s a tricky topic to cover in an email but I’ll do my best (a debate I sometimes enjoy when it’s the first time someone has had it explained properly):

You are right that traditionally all artwork prepared for print was best done in CMYK however with newer digital printers and inks things are not as simple as they used to be.

Where most people get confused is that the digital printer still uses CMYK inks and on the surface this seems simple to design in this Colour space – however the problem we face now is that the CMYK in your file (or default working CMYK space within Adobe for example) has nothing to do with the CMYK colour space in a digital printer. The space within your file relates to an international offset standard (such as “US Web Coated Swap” or “Euroscale”) and only really relates to how an offset printer is anticipated to produce that file.

This is where the problem is faced – digital printers and inks (particularly dye-sub, but any digital these days) has a MUCH larger colour gamut (or space) than these offset inks, and by using the offset setting within your file you are restricting the gamut (volume of deep colours) to only what that offset ink could produce and not taking advantage of the vibrancy and depth of colour that the digital printer is capable of.

Another thing about this that is important about this is that once this colour is clipped or lost at the design or file preparation stage – it is gone forever and by repeating the process in reverse it will not come back (by this I mean that converting an RGB file to offset CMYK will reduce the volume of colour, then converting that CMYK back to RGB will not put it back – it’s still gone).

Software has advanced a lot in the last 10 years and can as easily map from your files working space of colour wether it is CMYK or RGB however RGB has a much larger gamut than the printer and therefor does not bottle-neck colour to less than the printer can do prematurely BUT, RGB will be very well mapped from the larger space to the printers maximum (the ideal goal).

To some it all up simply – design in RGB for raster (photos) and Pantone for vector because these are the best possible “vibrant” colours, and the only time you need to worry about CMYK is at the last export of the file to go out of your office and only if it is going to be produced by offset or screen print and in that situation this loss of colour will be at your final step and not too early that quality is lost where it could have been better.

There is a lot more to this but this should be enough to hopefully explain why to design or create in RGB for digital output. Call if you ever want to ask any questions, I am happy to help where ever I can