Gallery

Living colour

Posted on 16 Jun 2008 at 12:01

For designers, the arrival (at last) of comprehensive control over CMYK colour handling is cause for celebration. Tom Arah explains how it's done.

One side of successful CMYK (Cyan, Yellow, Magenta and blacK) colour handling is practical, getting the printed result you expect (as detailed in last month's column). But how about aesthetics, making sure the result is attractive by choosing colours that work well together?

Choosing your base colour is the most important step, as it sets the look and feel of your whole design, so what message does each colour give out? Of course, there's no single answer to that, because everyone has their own preferences and sees colour differently. This subjective response to colour is quite fundamental: colour isn't out there, it's fabricated in your brain following the response curves of the red, green and blue cone cells in your retina. There's no way to know what colour anyone else sees in their mind's eye: my "green" might correspond to your "blue", or it might be completely alien to you. This lack of fixed standards turns out to be the key to understanding the effects of colour, because although I can't be sure you're seeing the same colour as me, we can all learn to apply the same broad labels to the same wavelengths. Most of us call grass "green".

It's through their associations in the external world that subjective colours derive meaning: light green looks fresher and younger than dark green thanks to the lifecycle of plants, sky blue suggests openness, and so on. These broad qualities are what you need to grasp and exploit in your work, and it should literally "come naturally" - you don't think "this looks a good place to add nature's universal danger signal", you'll just know instinctively that blood red will grab the readers' attention.

Having chosen a base colour to match the broad mood of your publication, how do you create it? I'll use the market-leading CMYK design application Adobe Illustrator as an example, but these lessons work for most print-orientated software. Illustrator's main Colour panel displays sliders for varying the cyan, magenta, yellow and black components of your desired colour, each with 100 discrete levels. The final printed colour is created as a halftone with percentage steps, which means there are 100 million (100 x 100 x 100 x 100) different colours available. In practice, as described last month, the black plate is largely there for press-related reasons to do with text definition and ink economy, so the CMYK colour space is mostly traversed via its C, M and Y components, which still leaves a core of around a million possible colours to play with.

So how do you create a particular colour, say an emerald green? Recent versions of Illustrator help you by smoothly colouring the cyan, magenta, yellow and black sliders to show the effect moving them will have on the current colour, but if you're starting from white with 0% of each ink, no green will be visible, because the full colour spectrum is attained only by mixing - drag up the cyan slider and the yellow slider will take on a greenish hue. Getting just the shade you want then becomes a trial-and-error exercise of dragging on the cyan, magenta and yellow sliders, using the black slider to darken the result. It's easier to get your head around than the counter-intuitive way RGB colours mix (where solid red and green produce yellow!), but it's still hardly natural or efficient. Fortunately, there's an alternative colour mixing option available: the HSB (Hue, Saturation, Brightness) model, available on Illustrator's Color panel menu, is much closer to the way we think about colour than either RGB or CMYK.