Understanding the difference between RGB vs. CMYK is crucial when trying to match your colors for printing purposes. Colors that may display brilliantly on your monitor may look differently when you get your document back from the printer. Here’s why.
Mixing red (R), green (G), and blue (B) can produce a large part of the visible spectrum. When these three colors overlap, they produce white, and hence this is known as an additive color model. Computer monitors produce colors by emitting light through red, green, and blue phosphors. But that only explains part of it. Your monitor settings can be customized depending on your preference and hardware such as your graphics card.
Monitors have various display settings, such as 256 colors (8 bit), high color (16 bit), or even true color (32 bit). If you’re using true color, you’ll notice a world of difference when compared to 256 colors. You can also adjust settings like your monitor’s brightness or play with the color levels pretty easily – processors very similar to changing the brightness and color levels on your tv set. Therefore, a color on one computer can look completely different on another computer.
This “subtractive” model is based on combining the colors cyan (C), magenta (M), and yellow (Y) to produce black (K). However, this is never quite achieved during printing because all printing inks contain some impurities & the end result tends to be a brownish color that must be combined with black to form a true black color. Because of this, not all colors that can be mixed on the computer in RGB mode can be made in real life.
Another major factor in the difference between monitor display and print is the direction the light is coming from. Your computer illuminates the screen by displaying a light from inside the monitor and projecting it outward so the colors are actually being lit from behind. With print, obviously, you’re not holding your paper up to a light source and looking through it to see the colors – the light shines down and the paper absorbs/reflects color – so the type of paper you use also plays a major role in how colors are displayed.
This is why you always need to allow enough time to get a printed color proof from your printer before you print your final piece. (Using CMYK for printing is known as 4 color process.)
If you are determined to use one specific, unvarying color, then selecting a Pantone is going to be your best bet. Pantone provides a number of inks that you can use alone or in addition to your CMYK printing. Keep in mind that the more Pantone colors you choose, the more expensive your document is going to be. (If you decide to use a Pantone color in addition to CMYK, that’s 5 inks instead of 4.) However, you will be able to guarantee that your color will be identical throughout all your printed pieces. More information on Pantone colors can be found on their website.