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Re: Colour contrast algorithm when black is used

From: Patrick H. Lauke <redux@splintered.co.uk>
Date: Sun, 20 Aug 2017 18:10:57 +0100
To: w3c-wai-gl@w3.org
Message-ID: <5e19b960-675d-e30c-8704-9aa978d24571@splintered.co.uk>
On 20/08/2017 11:41, David MacDonald wrote:
> There recently was a Twitter discussion about colour contrast combinations.
> https://twitter.com/davidmacd/status/899215930445754368
> There seems to be consensus from stakeholders that when black #000000 is 
> contrasted against some colours, the 4.5 threshold is met even when it's 
> hard to see. I've noticed this for years, and it seems others have too, 
> but the Twitter discussion got me thinking about it again.
> Black against #777777 passes, and black against dark orange passes, but 
> to the eye, white #FFFFFF which fails, seems much more readable against 
> this grey  or against this orange.
> There is something about black #000000 which needs a little tweak in the 
> algorithm.
> Perhaps when black is against colour spectrum X, it requires a higher 
> contrast minimum?

Are you sure it's literally *just* full #000000 black? What about 
#000001? My point being that it's perhaps not just about that one 
particular color, but more about a particular part of the spectrum / the 
color space used?

Patrick H. Lauke

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Received on Sunday, 20 August 2017 17:11:21 UTC

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