CMYK versus RGB
Let’s continue looking at specific publishing terms that can be confused (and that may be to some, a bit obscure.)
Both CMYK and RGB are related to the color model for images. (CMYK is listed in our Publishing Glossary, posted here.)
Here’s what The Chicago Manual of Style says:
CMYK
An abbreviation for the basic colors used in process color printing—cyan (C), magenta (M), and yellow (Y), plus black (K)—to approximate all the colors in the spectrum. (From The Chicago Manual of Style, 17e.)
RGB
An abbreviation for the additive color model that uses red (R), green (G), and blue (B) pixels to render color images on displays for computers and other devices. RGB images are converted to CMYK for printing. (From The Chicago Manual of Style, 17e.)
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(Note that these are pronounced “see em why kay” and “are gee bee”.)
It’s important to understand the differences when preparing images for either online or print use. Straight out of a digital camera, your images will be RGB. And in most cases you should leave them that way.
As noted in the definition, RBG is an additive color model: Additional colors are created by combining colors. In contrast, CMYK is a subtractive color model. The color range is more limited than it is with an RBG model. That’s why when an RGB is converted to CMYK, it will tend to look less vibrant and somewhat duller.
Such a conversion it typically done in a program such as Adobe Photoshop.
If preparing any images to be printed in color, these can be saved as CMYK (which is what the printer will use), but be careful: Trying to convert CMYK to RGB will produce the more limited range of CMYK. Once the model has been changed to CMYK, the color range won’t be recovered.
It’s advisable not to mess with the color model at all: If the image will be included in a printed book, leave this to the graphics people, such as the professional graphic artists at Virtus.
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