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Re: Color contrast principle

From: Detlev Fischer <detlev.fischer@testkreis.de>
Date: Wed, 16 Jan 2019 19:25:16 +0100
To: w3c-wai-gl@w3.org
Message-ID: <9bd64ef5-17b4-c31b-6756-d81f366e8507@testkreis.de>
sounds good to me

Am 16.01.2019 um 19:04 schrieb Alastair Campbell:
> 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
Detlev Fischer
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Received on Wednesday, 16 January 2019 18:24:42 UTC

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