RE: low light contrast ration calculation

Hello Jim,

Thanks for the reply! Can you please confirm my understanding of the contrast ratio formula… The current contrast ratio formula does not take into account low lighting conditions, and instead only accounts for normal ambient light. Is that correct?

Also, to meet accessibility standards regarding contrast ratios- do we not need to account for lighting conditions then?

Thanks,
Rachael

Rachael  Daniels
Sr. Human Factors Team Lead, User Experience
rachael.daniels@cerner.com<mailto:rachael.daniels@cerner.com> | 816.888.2663 direct
Cerner Corporation | www.cerner.com<http://www.cerner.com>

From: Jim Allan [mailto:jimallan@tsbvi.edu]
Sent: Thursday, August 24, 2017 2:11 PM
To: Daniels,Rachael <Rachael.Daniels@Cerner.com>
Cc: public-low-vision-comments@w3.org
Subject: Re: low light contrast ration calculation

WCAG20 has the provided the stated contrast ratios. And it provide this additional information https://www.w3.org/TR/UNDERSTANDING-WCAG20/visual-audio-contrast-contrast.html<https://na01.safelinks.protection.outlook.com/?url=https%3A%2F%2Fwww.w3.org%2FTR%2FUNDERSTANDING-WCAG20%2Fvisual-audio-contrast-contrast.html&data=02%7C01%7CRachael.Daniels%40cerner.com%7C5aa7783c16e9412a549c08d4eb23d708%7Cfbc493a80d244454a815f4ca58e8c09d%7C0%7C0%7C636391986545098181&sdata=dSjuslepXlEvQRRM%2FAvWT%2FoEj77FFuDaRnoSJBVhhNM%3D&reserved=0>

There are no other WCAG20  contrast ratios.

Jim

On Wed, Aug 23, 2017 at 1:11 PM, Daniels,Rachael <Rachael.Daniels@cerner.com<mailto:Rachael.Daniels@cerner.com>> wrote:
Hello!

The current contrast ratio formula does not take into low lighting conditions, and instead only accounts for normal ambient light. What is the contrast ratio formula that I can use to ensure we are following standards for low lighting conditions?

Thank you,
Rachael

Rachael  Daniels
Sr. Human Factors Team Lead, User Experience
rachael.daniels@cerner.com<mailto:rachael.daniels@cerner.com> | 816.888.2663<tel:(816)%20888-2663> direct
Cerner Corporation | www.cerner.com<http://www.cerner.com>



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Jim Allan, Accessibility Coordinator
Texas School for the Blind and Visually Impaired
1100 W. 45th St., Austin, Texas 78756
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