In contrast, color contrast analyzers use algorithms from the Web Content Accessibility Guidelines (WCAG) to obtain verifiable, objective results for luminosity, brightness and contrast. Those results give us an impression how fore- and background colors are perceivable by other people.

An example

Visiting the iTunes store we can say subjectively that the light gray text on a dark gray background is somehow hard to read. It’s straining, and possibly that’s not only due to the small font size:

If we check it with a color contrast analyzer, we get results like these:

The luminosity contrast ratio is sufficient with 5.37, the difference in brightness only just fails with 116 (125 being the lower limit), and the difference in color is insufficient with a result of 348 (the lower limit is 500).

So it’s not us getting old — the color values are indeed poorly chosen!

Downloads and links

There are various tools to test color contrast:

• Firefox Add-Ons: Colour Contrast Analyser and Juicy Studio Accessibility Toolbar
• Internet Explorer: Web Accessibility Toolbar 2.0 (WAT)
• Opera: Web Accessibility Toolbar 1.1
• Colour Contrast Analyser 2.2 as standalone software for Windows or Mac OS

As web application:

• Juicystudio Colour Contrast Analyser
• More resources listed by the W3C