The terms RGB stands for red, green, and blue spectrum lights used by digital cameras, scanners, and computer monitors. CMYK or cyan, magenta, yellow, and black inks on the other hand is used by printers to print and get a wider range of colors on a sheet. This is known as four color process printing and is used in many advanced printers.
The overlaying colors in RGB and CMYK are very different from one another. Many bright colors that you see on your screen or digital camera cannot be printed precisely onto a sheet. These RGB colors that cannot be replicated by a standard CMYK printer are known to be “out of the CMYK color gamut.”
The difference in the colors is not noticeable when you are printing a colored photograph with mild colors. The difference is accentuated when you use a pure, bright, and bold color from the RGB format to be replicated on sheet via a CMYK format printer. In order to reduce the differences while printing from a four-color printer, all the RGB color pictures need to be first converted to a compatible CMYK color format.
How to Increase the Color Accuracy
Pantone Process Color Guide is a useful tool to convert RGB color format to reproducible colors in the CMYK color palate. With 3000 colors on display, this swatch tool can be obtained in both uncoated and coated stock. All the displayed 3000 colors are available with color builds corresponding to the colors on the screen. If you have to reprint a poster many times, using the the Pantone Guide helps maintain uniformity in all the prints.
The RGB-to-CMYK conversion can be done by any standard graphic designing tool which is readily available in the market. You might have to do some work on the image files in order to convert the colors according to your choice. A standard rule does not follow for images, so the color needs to be carefully adjusted for each project in hand.
Custom printing is another process in which you can use a specific color cartridge to print a color that is not otherwise achievable via the process ink. These types of colors are referred to as PMS colors.
Another approach to achieve exact same colors in your printed product is to calibrate your monitor according to the CMYK color scheme. It is important to keep in mind that different monitors display different levels up to which the graphics and colors can be calibrated. CRT monitors show the finest color resolution followed by flat screen LCD monitors.
Other factors affecting the accuracy of color on the print are the brightness settings, contrast, temperature, and frequency of your monitor. Other fine adjustments that can increase the accuracy of the printed photograph, such as the fine adjustments of red, blue, and green color channels can be done. Since monitors display pictures with light, the printer will still have some limitations in reproducing the image on paper. Through all these discussions it is clear that the quality of color will be different from the colors on your monitor.
For more questions about getting the right colors for your print job contact our Color Department at 757-545-7675.