RGB vs. CMYK

Your web designer keeps asking for things in RGB and your printer needs them in CMYK. You've always wondered what the difference is and now its time to dig in and find out!

Your computer monitor will emit color by merging red, green and blue light (RGB). All colors of the visible spectrum can be produced in this way, however your screen is only capable of displaying a limited range of these colors.

When you go to print the paper itself absorbs or reflects specific wavelengths. The colors cyan, magenta and yellow serve as filters to subtract varying degrees of red, green and blue from white light to produce a selective range of colors.

This is the basic difference between RGB and CMYK. Now lets dig a little deeper...

When printing artwork developed in RGB format you can often see dramatic color differences. This is because the ranges covered by RGB and CMYK do not completely match. The picture on the right details which areas of the color spectrum are obtainable in each format as well as on your monitor. This same color change will take place when converting a CMYK file to RGB.

To further increase your ability to match colors in your file to the output from your professional printer it is important to use pantone colors. Using pantone colors will give your printer an actual ink to use on your work. It is possible to match any CMYK color up to a pantone color.

However, their are some advantages to working in RGB mode. RGB images are 25% smaller and therefore faster to work with and easier to store. Also, the SWOP CMYK gamut is pretty small. If you ever want to reproduce those files for a different medium (such as the web), you'll have thrown away some potentially useful information.

One way to save the quality of work when moving from RGB to CMYK is to merge the layers when you change the mode. This helps to preserve the overall blending quality of the layers. Also, leaving multiple blending options in your file will cause the printer to use more ink.