CMYK: what it is and how it affects your print projects |
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CMYK is at the heart of every successful colour print job, regardless of its size or complexity. If you have a good understanding of how colour printers and presses use CMYK to define colour, you are well on your way to successfully creating colour print jobs from your favorite colour laser printer or your local print shop.
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Color on screen vs. colour on paper |
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Have you ever sent a colour print job to a commercial printer or even the colour laser printer down the hall only to get back a printout whose colours are different from the ones you painstakingly created on your computer screen? Chances are that the way your monitor displays colour compared to the way that a printer prints colour are driving these differences. You might be surprised to find out that monitors and printers do not work with colour in the same way.
The way that we see colour in the world and on our computer screens has everything to do with light. Your computer monitor uses a combination of red, green, and blue (RGB) light beams to display more than 16.7 million colours. In contrast, almost all commercial presses and a healthy portion of colour printers use a combination of four colours -- cyan, magenta, yellow, and a key colour (CMYK) -- to represent all of the colours on a printed page (somewhat less than 16.7 million colours).
Think of RGB and CMYK as two different languages of colour. For your print projects you have to learn how to "speak" CMYK, or more accurately, how to use your computer to create files that a CMYK-based printer or press can understand.
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Defining colour with CMYK |
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As you just learned, CMYK models each colour as a combination of different shades of cyan, magenta, yellow, and a key colour. The key colour is almost always black (only very special printing instances use something other than black as the key colour), so CMYK could be called "CMYB." Color printers (both laser and inkjet) as well as professional printing presses are stocked with inks in these four colours and use unique combinations to create every colour on the printed page.
For instance, bright pink is 2% cyan, 83% magenta, and 0% of both yellow and black. The percentages don't add up to 100, but instead reflect the proportion of each ink's full strength used in the mix to create the final colour. Pumpkin orange (or a close approximation thereof) is 0% cyan, 72% magenta, 83% yellow, and 0% black.
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Using CMYK in the real world |
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What does CMYK mean to you? Remember that the computer monitor that displays the electronic version of your print job uses RGB to define colours, but your printer or press uses CMYK. Many RGB colours have CMYK equivalents, but the best and safest way to know what a printed colour will look like is to get a commercial colour guide or process colour book. These are printed books that contain hundreds if not thousands of colour chips that show you exactly what a colour will look like when it's printed. You usually have to buy these guides, and different ink companies like Pantone or Agfa have their own versions, so find out from a professional printer what inks they are using. If you have a laser or inkjet printer, find out which company colour model the printer uses (HP printers use Pantone).
Every good graphics or page-layout tool (PageMaker, Photoshop, QuarkExpress, etc.) has CMYK options, so use your colour guide as the definitive resource for what a colour will look like as you build your documents on the screen and don't worry that what you see in RGB doesn't exactly match. In addition, many HP printers, like those in the colour LaserJet line, have built-in ColorSmart technology to help make printouts in CMYK match what you see in RGB on your screen without a lot of work on your part.
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Printable version
