Unfortunately, color is a far more complicated topic than most people realize, and it’s these complications that might be keeping your KDP book covers from looking great. Entire books have been written on the topic of color as it relates to viewing colors on a screen vs. viewing those same colors in print.
Even the simplest part of the issue continues to confuse people – beginners, amateurs, advanced amateurs, and professionals alike. I’m referring to this seemingly simplequestion: “Should I use RGB or CMYK?”
Even though there is an easy answer – RGB colors are what you see on a computer monitor and CMYK colors are what you see on a piece of paper that has been printed – it’s still confusing to many people because, for one thing there is not just one kind of RGB and not just one kind of CMYK. There are lots of different kinds of RGB and lots of different kinds of CMYK. And using the wrong kind of RGB or the wrong kind of CMYK will cause crummy-looking book covers, endless hours of grief, and unnecessary expense.
Why does my printed cover look so dull, drab, and horrible?
It’s all about color spaces and gamuts. Knowing what they are and how to use them makes a difference.
As you can see in the graphic below, the color spectrum visible to the human eye is a very wide gamut, while the various color spaces (the inner outlines), such as RGB and CMYK are much smaller.
This means that the colors you choose are going to look different sometimes very different, depending on the color space you are working in and how anyone is viewing those colors.
If you are working on a color file (such as a book cover) in Photoshop (or other image editor), you should be working in RGB. Actually, even if you convert the file to CMYK while in Photoshop, you will be seeing an approximation of colors because a monitor can only display RGB no matter what.
So, which RGB? The diagram below shows two RGB color spaces – sRGB (which is a good color space to use for website graphics), and Adobe RGB 1998 (which is often thought to be best for preparing a print job).
You can see that if you are working in the Adobe RGB 1998, many of the color tones you see on the monitor will look very different after conversion to CMYK and bring printed on a printing press…because the inks used on a printing press cannot create anywhere near the color variations as those displayed on a monitor.
Continue reading below the graphic.
You will see that the sRGB color space is also small. There are lots of colors outside its gamut that will not show on lots of lower-end computer monitors..but still, that’s what’s best, considering the huge variation of monitors that will view a website.
The Adobe RGB 1998 color space is larger, but still leaves out a lot of the best and brightest colors. That’s just the way it is…and it is still much larger than the CMYK color space (which is what is used on a printing press.
There are many other variations of RGB, but sRGB and Adobe RGB 1998 are the ones you need to know about.
To get the best results when preparing anything for print, most experts recommend using the Adobe RGB 1998 color space in order to get the best colors after the image is converted to CMYK
RGB is limited, but mostly, it’s good enough – actually it’s great as long as you are viewing colors on a monitor, but CMYK is another story
You will see that the CMYK color space is limited. Very limited. Most of the colors within the CMYK color gamut are more dull and less saturated. And all the best colors, the ones that are so bright and saturated are totally out of reach. CMYK is not only necessary, but it’s also not a disaster, as long as you realize that there are many colors (mostly bright and saturated) that just will not print on a printing press or most color printers.
Those beautiful colors, especially bright reds and vivid blues that look so great on a computer monitor will fade into something drab after being converted to CMYK and printed on a press. That’s life.
In addition to the difference in the color gamuts, another huge difference is the way colors are displayed. On a monitor, light is shining through the colors and then into your eyes. This makes for better and brighter colors. On a printed piece, the light is shining onto the paper and then bouncing back to your eyes. It’s never going to be as bright and colorful as what you see on a monitor.
Comparing RGB and CMYK in real life
Open the PDF file you uploaded to KDP for one of your paperback books. Now hold the actual printed book near the monitor. See the difference? Yes, the printed cover might look OK, but it’s definitely going to be less “alive” than what you see on the computer monitor. For some people, that’s OK – but you and I are not satisfied. We are disappointed. We want it to be better next time we print a cover.
Photoshop has a method for previewing where the problem colors will be before you convert from RGB to CMYK – it’s called the Gamut Warning, and when you view your image through the Gamut Warning command, the out-of-gamut colors will (temporarily) display as gray in order to show you that the colors you thought you would see later will not look the way you had hoped.
The graphic below shows three views of the same Photoshop gradient: Left side is Adobe RGB 1998. Middle is the same gradient in simulated CMYK. The right side is the Gamut Warning view, with the gray replacing the colors that will not print as you would like on a printing press.
Here are the decision points that cause the most confusion and trouble when preparing a document to print:
Should I convert the image to CMYK immediately, as soon as I start manipulating my graphics and setting my type, so that I will see what the file will actually look like later?
If I’m doing the entire cover in Photoshop, should I convert from RGB to CMYK when it’s ready to print?
Maybe. But be sure to check first with the Gamut Warning to see which colors are going to disappoint you when the cover is printed…and try to make adjustments.
If I am doing the entire cover in Photoshop, should I leave everything as RGB until I’m ready to save the file as a PDF file?
It depends. The conversion from RGB to CMYK directly in Photoshop may be different than the conversion during the PDF-creation phase, which you will not find out about until you view the PDF file…if ever.
If I am doing the entire cover in InDesign…importing my RGB Photoshop files into InDesign, arranging all the elements on an InDesign page, should I convert from RGB to CMYK immediately?
In most cases, you can’t do this anyway, so don’t worry about doing it this way.
If I am doing the entire cover in InDesign…importing my RGB Photoshop files into InDesign, arranging all the elements on an InDesign page, should I use the PDF options to convert to CMYK during that phase?
Hard to say. This can be a good option, even though the RGB to CMYK conversion engine is different in this method than doing the conversion in Photoshop. The problem here is that there are so many PDF-creation options to choose from during this function. There are at least six Adobe PDF Presets to choose from. Which one to use?
Further into the process, you will have to decide if you want to convert your colors to the destination or not, along with many more options to choose from. Every one of these options can and will give different results when your cover is printed, and also may cause KDP to reject your cover file if you have an incorrect combination of options.
This sound hopeless. I’m lost. What should I do?
Amazon KDPs documentation is hopelessly incomplete and fragmented. The YouTube world of “how to” videos related to KDP printing is filled with incorrect, worthless, useless, information and misinformation…along with a very few videos that explain things correctly. So let’s think about this for a minute.
What does KDP say about this?
Very little. They talk all around the issue. KDP’s documentation is frustrating to say the least, but buried deep in in one of the paragraphs, they say that your PDF file can be OK when submitted as either RGB or CMYK. Wow. This is something that most people seem to have missed.
OK, so what should I actually do?
Create your print files in Adobe RGB 1998. That’s the best color space for working on your files. Check the colors with Photoshop’s Gamut Warning and work to get most of your colors within the gamut, realizing that the beautiful deep blue you wanted is just not going to print correctly. Do not convert to CMYK. Then, save your PDF file, either from Photoshop or from InDesign, with no conversion. Let everything remain as Adobe RGB 1998. Do not include any color profiles.
Then, assuming you have done everything else correctly, and you finally are able to approve your book cover for print, order a hard-copy proof of your book, and wait for it to arrive in the mail. If you’re not happy with the finished product (the proof), you should now have some idea of what adjustments you should make to get your colors closer to what you wanted…make adjustments and then run another proof. Continue until everything is OK.
You said nothing could be printed from an RGB file.
Not really. Even with no intervention, an RGB file will still print. It just won’t print correctly. But don’t worry. The KDP print process (which is mostly described very poorly) will run your PDF file through a RIP (raster image processor) that will do the RGB to CMYK conversion and do everything else necessary for the KDP press to print your cover.
As mentioned previously, entire books (almost unreadable in their complexity) have been written on this topic, so keep in mind that what I have written just covers the basics in a simple way, hoping to help people struggling with the problems of color printing (especially on Amazon KDP book covers).