Have you noticed your printer colors don’t always match what you see on your computer screen? Think it’s your printer that’s bad? Not necessarily. Understanding the basics of color science along with RGB vs. CMYK will help you identify color matching problems. Luckily for most of us, the steps required to achieve good color matching are much easier today compared with just ten years ago. But if you’ve ever wondered, “What is RGB or what does CMYK stand for?” you’ve come to the right place! OKI has some tips and guidelines to help identify the cause of mismatched colors along with explanations of key terms such as RGB, CMYK, Gamut and Color Profiles.
What is RGB?
RGB stands for Red, Green and Blue which are the primary colors within visible light. All of the colors that humans see are created from combinations of RGB light being transmitted to our eyes. Examples of RGB light sources include the Sun, light bulbs, computer screens, traffic lights and smartphone displays?
When looking at a sheet of white paper, our eyes receive a balanced combination of RGB light being reflected off the paper’s surface. White light contains equal amounts of RGB light. The white paper simply reflects most of the white light provided by the Sun or by the lights in the room.
When we see color on a surface, we are seeing light reflected off the surface that is no longer equal parts of RGB. For example, the green grass outside is reflecting mostly green, while absorbing (not reflecting) some of the red and blue light transmitted from the Sun. In order to control the light reflected from the surface of paper, printers use CMYK toner or ink.
What is CMYK?
CMYK stands for Cyan, Magenta, Yellow and Black. By applying different combinations of CMYK toner or ink onto paper, we can remove (or subtract) some of the Red, Green and Blue light reflected from the paper’s surface.
What about K? Printers use CMY+K (also known as black). Rather than mix CMY together to produce black, printers utilize black ink or toner to ensure a pure black color. Also, using black toner and ink in place of CMY helps to reduce the amount of ink required, thereby saving money.
RGB and CMYK’s Relationship
RGB and CMY have a special relationship. Combinations of RGB create CMY, and likewise combinations of CMY will give us Reds, Blues and Greens.
RGB: Notice that the overlapping combinations of RGB circles create Cyan, Magenta and Yellow. The white spot in the center is the combination of R+G+B.
CMY: Overlapping combinations of CMY circles produce Red, Blue and Green. The black spot in the center is produced by combining C+M+Y. A wide range of colors can be created by mixing different amounts of C+M++Y. For example, mix 10 parts magenta + 3 parts of yellow to yield a variation of red. Add more yellow and the red starts to appear orange.
Color Gamut
A key concept in achieving color matching is understanding the range of colors that your device is capable of producing. Most importantly, the range of colors displayed on your computer screen is typically greater than the range of colors that can be produced by a CMYK printer. The range of colors that a device is capable of producing is known as its color gamut.
- Colors visible to the human eye
- Colors displayed on a typical computer monitor
- Colors that can be reproduced by a printer using CMYK toner or ink.
Notice that the computer monitor has a larger color gamut and is capable of representing a wider range of visible colors compared to a CMYK printer. Vivid greens and blues seen on your display cannot be reproduced with a color printer using only CMYK toner or ink.
Tips for Better Color Matching
One of the most frequent occurrences of color matching takes place when the RGB combinations seen on your computer screen are converted into CMYK toner combinations for your printer to use. Most digital color printers will handle the conversion automatically when they process your print job. However, it is possible that the printer may need to know more about the source of your RGB colors to provide the best match.
Converting from RGB to CMYK
One of the most frequent occurrences of color matching takes place when the RGB combinations seen on your computer screen are converted into CMYK toner combinations for your printer to use. Most digital color printers will handle the conversion automatically when they process your print job. However, it is possible that the printer may need to know more about the source of your RGB colors to provide the best match.
Each digital camera and computer monitor uses a different set of materials to produce reds, greens and blues. And each printer manufacturer has a unique set of pigments and colorants in their inks and toners. A combination of C+M+Y+K on printer A could easily yield a different color on printer B. Thankfully, nearly all modern color devices exchange color information using industry standard color spaces such as sRGB and SWOP CMYK.
Utilizing Standardized Color Spaces
We hope this guide has provided clarification when it comes to understanding RGB and CMYK and color matching. Make sure to bookmark this page as a reference for future print jobs. Happy printing!
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Article Provided by OKI Data 2014