RGB Colors on your computer monitor vs. CMYK printed colors
Viewing color on your monitor
Computer monitors and printers (or any other printing method) typically use two different color processes to reproduce color. Computer monitors use RGB to display color. RBG stands for Red, Green and Blue. Most printers use industry standard CMYK process colors for printing your document. CMYK stands for Cyan, Magenta, Yellow and Black. If you would like to print your own artwork or images with a printer, for best results, you need to convert any RBG images or artwork, to CMYK before you upload them. Sometimes you’ll see some color changes to the artwork or images when you make this conversion, so it’s better that you see the changes and make any necessary adjustments before uploading your file.
Also some colors that you see on your screen in RGB are very difficult to reproduce using CMYK (or any other printing method). therefore if you have the software that enables you to process your artwork or images into CMYK before you upload it, you’ll have a better idea of what you’ll get once the printed products are shipped to you.
Please note that some of the hardest colors to match going from RGB to CMYK are blues.
The differences between monitors
You also have to take into consideration that different monitor types display colors differently. For instance, many LCD or laptop monitors cannot display as much of a range of colors as other monitors. On these monitors, colors can lose contrast and many colors sometimes look similar to others (for instance, dark greens and browns).
Professional designers, printing and prepress companies use color-calibrated monitors to ensure that the color they see on their screens is as close as possible to the actual color of the file. It is not practical for most home users to purchase these very high-end monitors, and therefore they should understand that there will ALWAYS be variance from what they see on the screen to what they see on their printer, or any other output device.