a particular colour to represent invalid fields (ie “the fields in red are invalid” would be a failure).It is also important that you do not use colour alone to convey information. Logos and incidental text do not need to meet colour contrast requirements. With large text you need to meet a contrast ratio of 4.5:1. In order to pass colour contrast requirements at Level AAA, your standard text must meet a contrast ratio of 7:1. Large text is at least 18 points (0r 1.5em), or bold 14 point (or 1.2em). If you have large text, it only needs to meet a contrast ratio of 3:1. But don’t worry about the numbers – both the Juicy Studio and Paciello Group tools will tell you what does and doesn’t meet the standard. In order to pass colour contrast requirements at Level AA, your standard text must meet a contrast ratio of 4.5:1. There are no Level A requirements for colour contrast. WCAG2 has a number of different colour contrast requirements, depending on what level you are attempting, how large your text is and whether it is incidental information or a logo. What passes colour contrast requirements? TPGi has a very useful downloadable colour contrast tester – you just use the colour picker to literally pick a colour on your screen and it will tell you what level they pass. Juicy Studio has a fantastic colour contrast analyser – just plug in your foreground and background colour contrast values and it will tell you at what level they pass. This is the kind of thing that needs to be picked up in the design, and there are a couple of ways to do it. The most important thing to remember when it comes to designing an accessible web site, app or interface is colour contrast. I hope it’s not too late! Colour contrast Level 2: Screen reader View Firefox extensionĪpologies to all the GovHackers! I meant to post this yesterday, but was struck down with a migraine.Level 2: WCAG2 for content authors and managers.Level 2: Managing accessibility testing.Level 2: HTML5, Forms, ARIA and JavaScript features.Level 2: Tagging PDFs for accessibility.Level 2: Creating accessible Word documents.Level 2: Accessibility in the web development lifecycle.Level 2: User testing with people with disabilities with assistive technologies.Level 2: Video transcripts, captions and audio descriptions.Level 2: Accessible Word, PDFs, PowerPoint and HTML documents.Level 2: Accessibility testing during the web development lifecycle.Level 2: Testing mobile sites and native apps for accessibility.Level 2: Testing websites and applications for accessibility.Gez Lemon provides more details about the difference between the Luminosity Contrast Ratio algorithm and the old one (referred to as the AERT algorithm) in Luminosity Contrast Ratio Main Colour Contrast Analyser. A couple that do are Gez Lemon’s Luminosity Colour Contrast Ratio Analyser and The Paciello Group’s Contrast Analyser. Check that the tool you use for analysing colour contrast lets you choose the Luminosity Contrast Ratio algorithm. Since WCAG 2.0 is now a W3C Recommendation I think it’s in place with a reminder about this. WCAG 2.0 recommends using luminosity contrast ratio to check colour contrastĪ little over three years ago I posted Luminosity contrast ratio, in which I mentioned that WCAG 2.0 recommends a different algorithm for calculating colour contrast than the one suggested by WCAG 1.0.
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