Colour contrast accuracy in Ally

[ClunyMcConville]

Hi there, my Learning Design team is aiming to improve our accessibility practices and I've been using Canvas Ally tool to check the contrast between emphasis boxes and link text in our organisation's CSS. Ally has been flagging a lot of instances of contrast being lower than 4.5:1 for normal text (as per WCAG Level AA guidelines).

These emphasis boxes are part of our larger organisation's branding and my immediate team is not in control of the CSS, so I thought I'd dig a little deeper before I escalated the issue. I decided to double check the contrast using the WebAIM contrast checker and also the University of Washington's contrast checker, According to both of these tools, our emphasis boxes and link text meet the Level AA requirement of 4.5.1 (being 6.18.1).

I'm therefore wondering how accurate the Ally checker is and if I should rely on it to check contrast? And does anyone else have any instances of Ally misjudging Level AA compliance that I should be aware of? 

Thanks in advance! 

[Gabriel33]

I don't have Canvas Ally, but just to make sure you're not making the mistake I did just a few weeks ago, does the text color look black, and you are imputing 000000? Or did you get the exact text color (and perhaps it is 000000)?

Often, text is a dark gray instead of black, like in this forum. That can drop contrast by quite a bit.

[ClunyMcConville]

Hi, thanks for the reply. I've been taking the exact HEX colours and testing them using the WebAIM tool, so I think it should be accurate.