RGB vs. CMYK

Understanding these concepts can improve your digital photography

RGB and CMYK are used to describe color in the digital photography world. If you're a photographer, an understanding of the two is crucial, because they have a great impact on the color of your photographs, both on screen and in print.

RGB vs CMYK

Overall Findings

RGB
  • Stands for red, green, and blue.

  • Combines three primary colors to produce different colors. 

  • Mostly associated with computer displays.

CMYK
  • Stands for cyan, magenta, yellow, and black.

  • Uses those colors as filters to subtract various amounts of red, green, and blue from white light to produce other colors.

  • Mostly associated with printing.

The quickest way to explain the difference between the two is that RGB is for the web and CMYK is for prints. It's a little more complicated than that, though, so let's take a close look at the color spectrums.

RGB Pros and Cons

Advantages
  • Wider color variety.

  • Industry default for computer screens and DSLRs.

  • More flexible than CMYK.

Disadvantages
  • Needs to be converted to CMYK for printing.

  • Slight inaccuracy between the monitor and the print.

RGB stands for red, green, and blue—the three colors that can be mixed to produce different colors. It's an additive color spectrum that relies on adding different amounts of the three colors to make different colors. The RGB spectrum has 256 levels of brightness, which in turn produce 16,777,216 (256 x 256 x 256) color possibilities.

When you take a photograph on your DSLR, your camera composes the shot using an RGB spectrum. Computer monitors also work in RGB, so it's easy for users to expect what they see on their LCD screens will be what they see on their monitors. Therefore, RGB is the industry default for DSLRs and computer monitors, because it allows us to view colors true-to-life on screen.

Setting each RGB color to 0 produces black. Setting each to 255 generates white.

CMYK Pros and Cons

Advantages
  • Industry standard for printing.

  • Many printers now convert from RGB to CMYK automatically.

  • Used by most home printers.

Disadvantages
  • Conversion from RGB to CMYK isn't perfect.

  • Less color variety.

  • Blacks can appear too rich when converted from RGB.

CMYK stands for cyan, magenta, yellow, and black. It's a subtractive color spectrum that uses those colors as filters to subtract various amounts of red, green, and blue from white light to produce different colors.

Therefore, an image displayed on a computer monitor might not match a print, unless the RGB spectrum is converted to CMYK. Although many printers now convert from RGB to CMYK automatically, the process is not yet perfect. RGB doesn't have a dedicated black channel, so blacks often appear too rich. 

So Which Should You Choose?

Whether you go with RGB or CMYK largely depends on the medium you're working with. If you're going digital, you'll probably want to use RGB. If you plan on printing your work, you might want to use CMYK.

Most desktop printers in homes and offices use CMYK inks. The printing technology in both software applications and printers now does a very nice job of automatically converting RGB colors into CMYK.

For the most part, you don't have to worry about conversion on a home printer. If you find that your blacks are not quite right, however, try converting to see if that helps.

Although some commercial printers might ask you to convert a photograph to CMYK, it's not common. This is particularly true when you're using a photo printing lab. Their software and technicians can handle most color challenges to produce the best photographic prints possible. They want to make the customer happy and know that not everyone has a full understanding of the technology involved.

If you take your work to a dedicated graphics printer for items such as postcards, brochures, etc., they might ask for the image in CMYK. This is because it's the format that they've always worked with. CMYK, also known as four-color printing, dates back to the days before digital technology was even imagined.