While most indie books are sold as e-books, many authors like to have the option available to buy print books as well. If you are planning on having a print version of your book, it’s a good idea to learn the differences in how printers make colours, as opposed to how screens do.
Your computer monitor is backlit (as is your TV, phone, and tablet). This means that the image is created by light shining through the screen from behind. When you look at a printed object, you are seeing the light bounce off the paper and back to your eyes.
Backlit devices use RGB colour. RGB stands for Red Green Blue. These are the three colours that you see on your screen in various intensities. They start out as their colour and become whiter as they get more intense, creating the image you see on the screen.
Printers use CMYK colour. CMYK stands for Cyan Magenta Yellow blacK. Yes, black is the K, it stands for Key. So, the printer physically has ink in these four colours and sprays them onto the white paper, creating the colours you see on a printed image.
Alright, so why does that even matter?
Well, here’s what happens. You create a book cover on the computer, using RGB colour, because it’s the default. It looks great. You send it off to the printer where they change the file to CYMK and the colours shift. They have to, because CMYK simply can’t print the exact same colours that you see on the screen. Sorry. Some people won’t really notice, and some printers do a good job of translating the colours, but if you are someone who has an eye for detail, you will notice. And you will be annoyed. Typically the colours will print duller and darker, and there are a few colours that simply won’t work. Neon colours, bright purple, and bright cyan have fared the worst in my experience. I tend to make covers with a lot of solid, bright colours, so it’s even more obvious than it would be with a photo.
So what can you do about it?
Check if the program you use has the option to change your colorspace to CMYK. I work in Photoshop, which makes it easy, just look under Image > Mode and select CMYK. When I’m illustrating a cover for print, I always set the colorspace to CYMK before I even start, this is the easiest way to not be disappointed by the limitations. The same applies for photo covers, you should have the file set to CMYK, then when you add the photo in, you’ll be able to see how it shifts. I like to have the original photo up as well (the easiest way is to have them both open and then go to Window > Arrange > Two Up Vertically) this way I can see how the colours shift and can adjust the CYMK version to be as close to the original as possible.
Sometimes, when I know that the cover will be seen 99% online, and I really want to use a colour that CYMK won’t support, I make two versions and make the web version nice and bright, then tone it down for print. I did this for Kelly McClymer’s Cozy Mystery, License to Shop.
Working in a CYMK colourspace is a good start, but that isn’t enough to get the image on your screen to be a perfect preview of what the printed image will be. Monitors are inconsistent and change quite a bit from one to the other. Have you ever used someone else’s computer, or a work computer, and noticed that the screen looks dark, or too bright and washed out? Not everyone seems to notice, but if you have an eye for detail, I’m sure you have. So if your cover looks great on your screen, but way too dark on someone else’s, which do you trust? Well…neither. You need a monitor that is calibrated, otherwise it’s just arbitrary.
A good place to start is calibration software, check on your computer to see if there is something included (I run Windows 7 and it has a calibration tool included under Start > Control Panel > Appearance and Personalization > Display). If you are serious, your best bet is to invest in a callibration device like a Spyder.
Long story short
Computers and printers make different colours, so if you want your book cover to look the same when you print it as it does on the computer…create the cover in CYMK and calibrate your monitor!
This is how you get a nice image for print, but for your e-book cover, be sure to save the image in RGB. Otherwise it will look crazy bright and terrible when you view it online.