RGB vs CMYK: The Color Shakedown

cmykColor Basics

Color comes from light. Without light there is no color. The sun contains all the colors of the rainbow. When sunlight (or any light) shines on an object, some of it is absorbed, and some reflected. This depends on the characteristics of the reflecting surface, angle of light, and the light source itself. It is the reflected light that we see, which interacts with the light receptors in the eye, and is then interpreted by the brain to produce the range of colors we see. Learn more about color in the course Color Basics for Print Designers.

The Internet and Print World

The internet and the print world treat color in different ways. The reason for this is technical, but it’s important to understand how these differences affect the way you create content. RGB stands for red, green and blue and is the color model associated with computer screens, and is similar to how the retina interprets color. CMYK is the acronym used by the print industry, that uses cyan, magenta, yellow and black plates to mix colors. You can see CMYK on a computer screen, and RGB colors will print onto paper. The big difference is how light is reflected. Computer screens have a light shining behind them, and printed documents reflect light off their surfaces. This has an impact on how colors appear to the eye, and causes problems for graphic designers, who need a visual reference, or proof of what a print document will look like before it goes to print. Color management systems inherent in softwares overcome some of these difficulties.

Dots and Pixels

Both the CMYK and RGB color systems use a similar form of deceiving the eye to create color. Printed documents use tiny dots of color layered on top of each other, that the eye blends to create the impression of a color. Pointillist painters used the same technique to create famous works of art during the Impressionist period. For fun, have a look at a newspaper under a magnifying glass and see if you can find the little dots. Computers use pixels, which are tiny squares, and merges them to create the desired color. Now zoom in on an image on your computer until you will see the pixels appear.

Software

The major design software packages, such as Adobe Photoshop are able to convert between RGB and CMYK. Although there is no discernible difference on the screen, when documents are ‘output’ they must be converted beforehand into the relevant color model. Traditional printing, often referred to as offset lithography, requires that four separate metal plates are created for cyan, magenta, yellow and black for a four color print job. When graphic designers proof their work, they print out a page for each color plate. The document is first created, or typeset in a desktop publishing software such InDesign. Images imbedded in the document will already have been converted to CMYK. Similarly, an image to be used for a website may need to be converted from CMYK to RGB. To get around the problem of color discrepancies between a computer screen rendition, and the desired final output onto printer media, the designer will use color swatches, such as Pantone colors. These swatches are recreated in digital form in nearly all design softwares, and although they may look different on screen, the information contained in the saved document, will usually tell the printer which pantone colors to use. To learn more, check out the Photoshop CS6 Crash Course, Introduction to Adobe InDesign, and Adobe Illustrator CS6 (pro techniques for print and web).

Color accuracy that is for use in digital form can also be a challenge. This was especially true when computer monitors were only able to display a limited number of colors. Web designers had to use hex color codes that were considered ‘safe’ on the internet. Photoshop was used to convert an RGB, or a CMYK color to the nearest web safe color. Nowadays, color monitors can display a huge range of colors. Choosing colors for a website, can be done directly from a color palette in a design software, or the percentages of the color can be changed using a mixing palette. The same can be done with both RGB and CMYK colors. Software tools can analyze color on a screen, and determine color values.

rgbLess is More

The restrictions imposed by tight budgets in the print world have pushed the boundaries of creativity in ways that you don’t see in digital design. Since the cost of printing with four colors is high, graphic designers will often use just one or two colors, often referred to as spot colors, and create visually stunning designs by using different tints. Tints are measured in percentages of a color. For example a 50% tint of red is going be a paler version of the original red. Using several tints creates the illusion of many colors. Tints are not to be confused with shades, which is spot color combined with black to create darker versions of the original color. Using two colors allows designers to explore their relationship in great depth in very creative ways, which is much more difficult when many colors are present.

The Future

The internet and print worlds have been separated largely by the two different color models. Traditional printing is both a cumbersome and a costly process, whereas creating content for the web is comparatively easy. The development of digital printing has brought the two closer, as computers have removed some of the steps from design to print. Converting from one color model to the other is also a simple task. Perhaps the biggest change has been in the way we receive print documents, such as newspapers, and books. The Kindle and iPad have made big advances in displaying text and images on small screens, and to an extent have been successful in simulating paper. So is the print world losing ground to the forward march of digital delivery, and in danger of becoming obsolete? Not for the time being, since many consumers haven’t made the transition to non-paper based mediums out of personal preference, and paper still remains the medium of choice for industries such as the legal profession. A bigger threat to CMYK may come from digital printing, but for large print runs offset lithographic printing is generally cheaper.