RE: Sorted it out.

Ø  It only takes two pixels to create high contrast, but to a person with night blindness may not see it because the total amount of light (luminosity) may be to faint to see.

I agree the thickness makes a difference. That’s actually why I prefer low resolution over increased DPI settings in the OS.  That is the width of the stroke tends to impact my perceived contrast.  Other factors such as antialiasing play in as well.

Jonathan

Jonathan Avila
Chief Accessibility Officer
SSB BART Group
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From: Wayne Dick [mailto:wayneedick@gmail.com]
Sent: Wednesday, January 06, 2016 8:08 PM
To: public-low-vision-a11y-tf
Subject: Sorted it out.

To compute contrast we use luminance (luminosity per pixel) when we discuss the effects of brightness we are interested in the total amount of light emitted by a region the luminosity.  It only takes two pixels to create high contrast, but to a person with night blindness may not see it because the total amount of light (luminosity) may be to faint to see.
Wayne