Will my book cover look exactly the same as what I see on my computer screen?

In previous posts we discussed the content and design of a book cover. However, there’s a technical aspect to printing a book cover too. To make sure that the knockout cover that was designed turns out as great as planned, it’s important that it’s printed accurately, especially when it comes to color.

RGB and CMYK

As you are probably aware, most colors are made up of a combination of other colors. Purple paint is a combination of blue and red paints; green paint comes from mixing blue and yellow paints.

When it comes to creating colors digitally, there are two sets of primary colors that are commonly used to mix the colors: RGB (red, green, and blue) and CMYK (cyan, magenta, yellow, and black).

If you want to see how RGB works, open up a Word document. In the Home tab, click on the tiny down arrow in the bottom right side of the Font section. This opens up a drop-down menu; click on More Colors. Now a new window opens; click on the Custom tab. At the top, you have a table full of colors. It should say “Color Model: RGB”; underneath that are the three colors with number references to the right. You can experiment with adjusting the color values, adding a little more red, then green, then blue, and then more red again. The composite of this mix is represented in the sample square above and by the X in the chart.

In the CMYK color system, K stands for black. If you are wondering why it isn’t called CMYB, with B for black, you are in good company. The standard answer is that K stands for key, but the significance of this, as well as the technical differences between the two color modes, is beyond the scope of this post. For those who wish to enrich their knowledge of this subject, here is a link to an excellent article to get you started.

The black produced by K is 100% pure black, and it looks a little dull. There is actually another type of black called rich black. In order to give it a little more shine, some of the other three colors are mixed into the black to create a richer effect. As a rule, offset printers can print rich black, but digital printers cannot handle it. Always consult your printer before finalizing your print files.

The Differences

So, what is the practical difference between RGB and CMYK? When do you use one, and when do you use the other? The answer is that the color system you should use depends on how your final image will be produced.

RGB is the color mode used by your digital camera and computer monitor to create color, and CMYK is the color mode use by professional printers. Therefore, if you are preparing a file for viewing on a computer, such as with web material, the colors should be prepared in RGB mode (your digital photos will look perfect). But if you are creating a file that will be sent to a professional printer, then the color mode should be CMYK. Desktop printers also work with CMYK.

These two modes create colors that are similar colors but not always identical, so it is ideal to avoid converting from one to another. There are also some colors that RGB can produce that can’t be made with CMYK. And sometimes color converted from RGB can look duller in CMYK, especially if there are large areas of a solid block of color.

Issues

What happens when a CMYK printer receives a PDF that was made using the RGB color mode? Sometimes the printer uses software that converts the color mode to CMYK for printing. However, some printers simply won’t print a file made with the wrong system. I assume they don’t want to take the risk that the color conversion will disappoint the customer and be left with a bad reputation. If you find yourself in this situation, find a PDF tool that can convert the files to CMYK, verify that the colors came out to your satisfaction, and then send the files to the printer.

Another issue that can arise is when a digital photo is used on a book cover. The photo is in RGB mode, but the cover will be printed in CMYK mode. In this case, though, the cover designer is probably working with a professional program that can convert the image to CMYK for printing. Nevertheless, it is worthwhile to test the output before ordering a full print run.

Most of the time these aren’t serious issues. The most problematic situation is when a very specific color is needed. For example, if a company logo is placed front and center on the book cover in order to solidify a branding effort, the designer should be careful to use the correct colors from the start in order to avoid any accidental mismatches.

Fine Tuning

So far we’ve dealt with the colors produced by the RGB and CMYK modes, but there is another factor that comes into play too: the computer monitor. Aside from the fact that it operates in RGB mode, there are other things that influence the way the actual color appears on the screen compared to what you might see on the page. The brightness, contrast, and color-temperature settings on a monitor can make colors look brighter or darker than they really are. If these details are significant to you, then you should learn how to calibrate your monitor to the most realistic settings to view your documents.

Communicating

Careful calibration and attention to details can help with the technical aspect of printing accurate colors, but there are human challenges too. Communicating clearly and correctly about colors is important.

A publisher might want the lettering on a book cover to be red – But how dark or light should it be? There are tens of shades of red. Which is the right one? And once you’ve chosen just the right shade of red, how can you make sure a graphic designer knows which one you’d like to use?

One solution is to go into Word and play around with the color settings until you find the color you are looking for and then relate the RGB code to your graphic designer. But fiddling with the controls until you find just the right one can take a lot of time and become frustrating.

Luckily, there are websites that have tools to solve these problems for us. One that I use is called w3schools.com. They have several different color tools, including lists of names, values, groups, shades, and more. They also have tools to help you convert an RGB value to CMYK, and vice versa.

Printers

I mentioned that professional printers work in the CMYK color mode. But not all printing presses produce the exact same colors. As expected, there are high-quality printing presses that are excellent at matching colors, and there are lower-quality presses that produce average matches at best. You usually get what you pay for. So, if it is really important to you that the color comes out great, make sure that you are using the best printer.

See It in Full Color

As we’ve seen, there are many factors involved in color printing. By following the advice outlined above – choosing your color well, communicating exactly which shade you like best, saving the color in CMYK for printing (or RGB for web use), and choosing a top-notch printer – you have the best chance for the colors in your book’s cover to come out the way you envision them. But there are no 100% guarantees. The best way to be sure of the final product is to print a proof copy of your book. That way, you can avoid any unpleasant surprises and be sure that you – and your readers – are delighted with the results.