In graphic design and photography, color management is an essential component of the workflow to produce professional quality results. In my last article we looked at the basics of color management and how the content management system (CMS) handles color. In this article you’ll learn more about color modes and color profiles.
In graphic design and photography software such as Adobe Creative Suite, the color mode describes the overall color model used for the image or document. The color mode determines the format for the numeric values used to describe the elements in the file. The most common color modes are RGB, CMYK, Grayscale and Bitmap. RGB (red-green-blue) is most commonly used for digital photography and images for the Web. Your computer monitor displays color in RGB. CMYK (Cyan, Magenta, Yellow, blacK) is a color mode used for offset printing, as is Grayscale, which is mainly used just for one-color printing using halftones. (Bitmap is just black and white, used for high resolution line art and not subject to color management.) You can switch between document color modes in Photoshop and Illustrator, etc.
For each color mode, there are many color spaces available. Adobe RGB is an example of a common working RGB color space for digital photography. U.S. Web Coated (SWOP) is a common CMYK space used in Photoshop. Whereas the color mode defines the numeric model used for the color values, the color space determines the range of colors possible based on that mode.
An RGB color space has many more available colors than a CMYK color space. When you have an image that uses the RGB color space and you want to print it using CMYK, the content management system (CMS) must translate the colors from the RGB space into the CMYK space. In this conversion, some colors will not be possible to reproduce, because they don’t exist in the CMYK color space. For example, very bright, vivid colors can sometimes appear washed out in CMYK because there is no way to reproduce the RGB color values in the CMYK color space. In Adobe software, you can preview these conversions to see where there might be problems and make adjustments accordingly.
The figure shows the Photoshop Color Settings dialog box where you specify default working color spaces for each color mode.
A color profile is used to describe the color space of an image file, layout document or an imaging device such as a monitor or printer. For a graphic designer, it’s imperative that you always use the correct color profiles. When you save an image from Photoshop, be sure to embed the color profile. To be able to view accurate color on your monitor, you need to use a display profile. And when you prepare files for printing, you should use the color profile specific to the output requirements. When you’re working with a printer or other service bureau, they can advise you on the correct color profile to use for their process.
In future articles we’ll look at the best ways to handle color space conversions and preparing files for printing and the Web. Thanks for reading!