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Re: Color contrast principle

From: John Foliot <john.foliot@deque.com>
Date: Wed, 16 Jan 2019 16:51:05 -0600
Message-ID: <CAKdCpxzA4M7O64PdpY6XnDmaJyz7pLfL6+K__O=R0PWA6fjBeg@mail.gmail.com>
To: David MacDonald <david100@sympatico.ca>
Cc: Jonathan Avila <jon.avila@levelaccess.com>, Alastair Campbell <acampbell@nomensa.com>, "WCAG list (w3c-wai-gl@w3.org)" <w3c-wai-gl@w3.org>
I think the word we may be searching for is *subsume*

https://www.merriam-webster.com/dictionary/subsume

JF

On Wed, Jan 16, 2019 at 3:44 PM David MacDonald <david100@sympatico.ca>
wrote:

> Hmmm
>
> >The input also has a dark grey border which can be assumed to merge into
> the dark background. The border does not interfer with identifying the
> component, so the contrast ratio is taken between the white background and
> dark blue background.
>
> If the grey outilen is merged with the dark blue background wouldn't the
> contrast be between the input and the dark greay background. I think of the
> word merge to mean "part of", no?
>
> Cheers,
> David MacDonald
>
>
>
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> On Wed, Jan 16, 2019 at 2:11 PM Jonathan Avila <jon.avila@levelaccess.com>
> wrote:
>
>> I am fine with that.
>>
>> Jonathan
>>
>> Sent from my iPhone
>>
>> On Jan 16, 2019, at 1:05 PM, Alastair Campbell <acampbell@nomensa.com>
>> wrote:
>>
>> CAUTION: This email originated from outside of the organization. Do not
>> click links or open attachments unless you recognize the sender and know
>> the content is safe.
>>
>> Hi everyone,
>>
>>
>>
>> Busy day, just catching up, some comments before a suggestion:
>>
>>
>>
>> JonA wrote:
>>
>> > an adjacent point that is not immediately touching the initial point
>> can be used for the comparison when the sum of corresponding points
>> communicates the same information needed to identify parts of the control
>> or graphic and its states.
>>
>>
>>
>> I see where you’re going, but I’m wary of the ‘not immediately touching
>> the initial point’ aspect, I think a concept about combining / merging
>> areas would be more effective.
>>
>>
>>
>>
>>
>> Detlev wrote:
>>
>> > it is important to allow cases where (thin) outlines can be disregarded
>> if the colours they separate have enough contrast between them. It might be
>> necessary to define the upper limit of the line thickness though, in some
>> way, not sure how  (3 or 4 CSS pixels? Could appear arbitrary.)
>>
>>
>>
>> I’m not sure that it matters how thick it is, If something were a thick,
>> non-contrasting border it is considered merged. It would be very difficult
>> to bring in a concept of thickness at this stage, we need to base it more
>> around “Visual information required to identify user interface
>> components”.
>>
>>
>>
>>
>>
>> How about replacing the paragraph above the second example in Adjacent
>> colors with:
>>
>>
>>
>> If components use several colors, any color which does not interfere with
>> identifying the component can be ignored for the purpose of measuring
>> contrast ratio. For example, a 3D drop-shadow on an input, or a dark border
>> line between contrasting backgrounds can be assumed to merge into the color
>> closest in luminance.
>>
>>
>>
>> The following example shows an input that has a light background on the
>> inside and a dark background around it. The input also has a dark grey
>> border which can be assumed to merge into the dark background. The border
>> does not interfer with identifying the component, so the contrast ratio is
>> taken between the white background and dark blue background.
>>
>>
>>
>> Does that make sense to people?
>>
>>
>>
>> It’s hard to describe this simply, reading other people’s attempts makes
>> my head spin so I assume that’s what I’m doing to everyone else, sorry!
>>
>>
>>
>> Cheers,
>>
>>
>>
>> -Alastair
>>
>>

-- 
*​John Foliot* | Principal Accessibility Strategist | W3C AC Representative
Deque Systems - Accessibility for Good
deque.com
Received on Wednesday, 16 January 2019 22:51:59 UTC

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