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Re: 1.4.1 use of color for state indicator

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From: Jonathan Avila
Date: Mar 9, 2020 6:49AM

Hi Glenn, yes -- you'd want to take the contrast ratio before converting to grayscale as the calculation treats hues differently to help people with color perception challenges -- but applying a simple grayscale test would help people understand if it's really the hue or the luminance that makes the difference. For example, if you grayscale something and it says find the red text then it's obviously an issue. If you grayscale something and then you say which of your buttons is selected -- then you'd say -- the color (hue) doesn't make difference (e.g. whether it's purple or blue didn't matter) -- I'm really looking at lightness making a difference. As I understand it luminance and lightness are not the same thing -- but lightness is a easier to understand concept for me and most people. So if you then say it's lightness that makes a difference based on my grayscale tests -- then I go back to color and check the contrast ratio between the two items. So if the selected state only
relied on color difference -- does that selected state have >= 3:1 (I should have said >= in my prior email)?

Jon

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From: WebAIM-Forum < <EMAIL REMOVED> > On Behalf Of glen walker
Sent: Monday, March 9, 2020 8:21 AM
To: WebAIM Discussion List < <EMAIL REMOVED> >
Subject: Re: [WebAIM] 1.4.1 use of color for state indicator

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Thanks, Jonathan. That sounds nice but there's nothing in the success criterion to imply that. It makes logical sense, but it's not spelled out anywhere.

When you say "something" has a contrast greater than 3:1, is that something the two states? Selected and unselected, even though they're not adjacent colors?

As far as grayscale, I could take white and yellow, a contrast of 1.1, and when viewed in grayscale, the yellow will be slightly gray. Are you saying that would pass? Or are you saying convert the colors to grayscale first, then take the ratio of the resulting grays and see if it's greater than 3:1?

When you get into hue vs luminance, it's hard to explain to non-accessibility people (or maybe people in general) that 1.4.1 use of
*color* might not really mean color. Both red and pink are colors. Using one for one meaning and the other for another meaning is using two colors.
Saying that doesn't fail 1.4.1 because they're not really colors, they're luminance, just feels weird.