CMYK vs RGB???
When creating a design for print, there are many things you'll need to consider. You have to think about the layout, the stock (the type of paper) it will be printed on, and any extra finishing involved (creasing, forme cut, lamination and so on). All of this can feel a bit like walking through a minefield to the novice, but that's where an experienced printer can be worth their weight in gold. Unlike many other printers, at Saxon Print we take your precious artwork and physically look at it before going to print, advising on any tweaks needed to get your project to the standard you expect and deserve. We don't rely on fully automated processes that can miss obvious mistakes. You'll find a whole series of these guides on our blog.
Let's start with the difference between RGB and CMYK colour modes. "What's a colour mode?" I hear you cry. Do not fear, I will explain.
When designing something for the internet, you don't really need to worry about colour modes, as most colours will look fairly similar on most monitors. Screens all display colour in the RGB colour mode. It would be a mistake, though, to assume that the colours you see on screen while designing will stay the same once printed in CMYK. A designer getting this wrong can lead to a very unhappy client. So what exactly do RGB and CMYK mean, and when should you use each? We don't want to see you make the common mistakes many designers have, so here is our guide to the difference.
What is RGB?
RGB stands for Red, Green and Blue, and it's an additive colour model. A combination of red, green and blue light is added together to create a broad range of colours, eventually reaching white. To make yellow, for example, you add green and red light. To make a light blue, you add green and blue (this may seem counter-intuitive, but trust me, I'm a printer).
RGB is the standard colour mode for most applications because it offers such a wide range of colours. By combining red, green and blue in differing amounts, you can achieve almost any colour with great accuracy. Most photo-editing and desktop-publishing programs use RGB as standard (including Adobe Photoshop), which is exactly why you need to take extra care when designing for print.
What is CMYK?
CMYK stands for Cyan, Magenta, Yellow and Key (Key means black, and we'll call it black to save any confusion). CMYK works in a different way to RGB. It's a subtractive colour model, which means that as Cyan, Magenta, Yellow and Black inks are combined, they subtract light and you eventually reach black. Add cyan and yellow together, for instance, and you get green. Combine yellow and magenta, and you get red.
This works in the opposite way to RGB, and it uses a fourth colour rather than the three RGB relies on. As the colours combine, light is absorbed to create the various shades. Add cyan, magenta and yellow together in equal quantity (say 80% of each) and you get a dark brown. It's only when you add black (Key) that the light is fully subtracted to give a true black.
CMYK is the standard for professional press printing such as flyers, business cards and booklets, so if you want the printed colour to match your design, this is the mode to be aware of. (Giclée fine art printing is the one exception, which we come to below.)
An Example
Take a look at the image and you'll see how RGB and CMYK can differ. One of the most noticeable differences is the way the two modes reproduce blue. The main blue looks different in each version, and that's down to the colour mode.
Blues tend to look more vibrant in RGB than in CMYK. So if you create your design in RGB and print it in CMYK, you'll see a bright blue on screen, but the printed version will appear flatter and closer to a purplish blue. The same goes for greens and oranges, which can look a little flat once converted from RGB to CMYK. Brighter colours suffer the most.
When should you use RGB or CMYK?
This is a question we're often asked, and the honest answer is that it depends on what you're designing and how it will be used. If you're designing for the internet, work in RGB. If your design is heading for a printed product, there are times you'll want CMYK.
Most of the time you can work in RGB and convert to CMYK near the end of the design process, checking that the conversion looks acceptable before you send it off. Working this way lets you design with the full RGB range, with smaller files and more colour freedom along the way.
There are times, though, when it's worth working in CMYK from the start. If your design is mostly grey, for instance, you might design in CMYK. In RGB, grey is built from red, green and blue in roughly equal amounts, but grey is one of the hardest colours to control in print, and an RGB grey converted late can come out looking rather pink. In CMYK you have black (the Key colour) to control the process and keep grey looking as it should.
The exception: giclée fine art printing
Everything above applies to our press work: flyers, business cards, booklets and the like, printed with four process inks. Giclée fine art printing is different, and it's the one time you should not convert to CMYK.
For giclée we print on a large-format printer carrying eleven archival pigment inks, driven by a custom colour profile built for each paper. That reaches colours a four-ink press can't, particularly in the blues, cyans and greens. Convert a giclée file to CMYK and you squeeze it into the smaller four-ink space, losing those colours before we ever see the file, and the change can't be undone. So for giclée, keep your file in RGB, ideally Adobe RGB (1998), with the colour profile embedded, and leave the rest to us.
We explain the full story in Why Giclée Prints Stay in RGB.
To wrap up
Designing for print can be a straightforward process. As long as you're conscious of the difference between RGB and CMYK, and aware that what you see on screen in RGB won't always match what prints in CMYK, you can take the steps needed to avoid expensive mistakes.
For press work, remember that a design created in RGB needs converting to CMYK before it's sent off, and you may need to nudge some colours by hand afterwards to bring them back towards the original. For giclée, it's the reverse: leave the file in RGB and don't convert. Either way, it's always wise to print a hard copy before sending it to us, to check colour and layout.
If you have any concerns about colour accuracy or layout, talk to us before you start, email your file, and the spec of your project, to info@saxonprint.com we can produce hard copy proofs, give advice and adjust the files for you for a small fee. It can save the trouble of a print job not looking the way you hoped, not to mention the cost of reprinting.
And if you'd like to confuse yourself and learn a little more about colour theory, here is a good place to start.