(This article is intended primarily for printed book information, not eBook)
Simply put, you will experience the best results for your print project if you give us files in CMYK. Simple as that.
What is the difference?
CMYK is the the color model used by printers. This color model is built around applying ink to a substrate, in this case paper. It uses the light being reflected off the paper to create color.
RGB is the color model used by anything with a monitor or screen that displays color. It is the proper color mode to supply your images for eBook conversion. This color model uses the light of the device to create the color. Images supplied in RGB for your print book will be automatically converted CMYK. Because of the sheer amount of jobs we receive in this color mode, you will not receive an additional warning about this and the job will go to production if there are no other issues.
Spot colors are used in certain types of printing when a specific color is needed (most famously Tiffany Blue) or when you are doing like a 2 color newsletter (think black and white printing, but with a color ink instead of black). Only if you were quoting a special project for offset printing with us would you want or even be able to use a spot color, as most of our printing is done on a digital CMYK press. Unless you have discussed special arrangements with your publishing specialist, all spot colors should be converted to CMYK before supplying your files. We can perform the conversion, but you may not like the results of the conversion and wish to tweak them further. We do not receive many files with this error, so you may receive a warning asking you to correct, or verify that you want us to convert for you. Learn more about Spot colors here.
Let's see it in action.
Because RGB is the most common incorrect color mode in which we receive files, we'll start there. As we mentioned before, RGB uses its own light source. This means you can create some brilliant, almost neon colors. Let's take a look at some examples.
This is an extreme example of some of the brightest RGB colors available, an an untouched conversion. You could probably find closer matches, but this was to prove the point that you don't necessarily want a computer to handle your color conversion. Let's take a look at a less startling example.
This again is an untouched conversion. You could adjust these for a more vibrant conversion and still be within the CMYK color mode, but this demonstrates the difference well, and sets expectations for some changes you might see between a RGB supplied file and your printed book.
Keep in mind you are looking at this on an RGB monitor, and your color calibration is completely out of our control, so you are likely seeing different results than we are, but you should at least see a difference between the two examples.
Can't you just print in RGB?
No, the technology does not exist. If vivid RGB color is critical to your book, you may want to consider doing your book as an ebook. The iPad and other color readers will display your images in the RGB color mode.
Still not sure?
We offer a single copy proof for $39. It's a great way to see what your files will look like as a printed book before launching your full publish. Speak it over with your publishing specialist and decide what works best for you.