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Documentation > Contrast testing

The WCAG1 and WCAG21 accessibility standards both specify guidelines for testing the contrast between the foreground and background colours of text. Total Validator can carry out the appropriate contrast testing, but only when configured correctly, and with the limitations shared by all automated testing tools.

Due to our advanced HTML testing we can test the contrast of text in more scenarios than other accessibility validators, such as with the <input> element's latest type values in HTML5. But, because we use the formulas given in the official guidelines, we can only test displayable text and not text within images. The formulas also do not account for text with background images, gradients, decorations, or shadows. So, if your pages have any of these you may have to carry out some manual testing.

Running tests

For Total Validator to perform contrast testing you must be using one of our browser extensions. You can use the Validate DOM option in the application, or manually select the Send DOM option in the browser extension.

Testing from the command line, can only be performed using the CI version.

When a contrast issue is found it will be marked on the results page in the usual way. To prevent unnecessary duplication, and to simplify fixing, issues are only raised against the element that changes the colour, rather than for each block of text that fails.