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Re: G18: Description

From: Loretta Guarino Reid <lorettaguarino@google.com>
Date: Fri, 23 Apr 2010 18:39:22 -0700
Message-ID: <x2y824e742c1004231839pfd43f14fq3f746c03fcf27c1c@mail.gmail.com>
To: makoto.ueki@gmail.com
Cc: public-comments-wcag20@w3.org
On Sat, Jan 9, 2010 at 7:05 AM,  <makoto.ueki@gmail.com> wrote:
>
> Name: Makoto Ueki
> Email: makoto.ueki@gmail.com
> Affiliation: Infoaxia, Inc.
> Document: TD
> Item Number: G18
> Part of Item: Description
> Comment Type: general comment
> Summary of Issue: G18: Description
> Comment (Including rationale for any proposed change):
> Couldn't understand and translate the following description:
>
> "If the background or the letters vary in relative luminance (or are patterned) then the background around the letters can be chosen or shaded so that the letters maintain a 4.5:1 contrast ratio with the background behind them even if they do not have that contrast ratio with the entire background.
>
>
>
> The contrast ratio can sometimes be maintained by changing the relative luminance of the letters as the relative luminance of the background changes across the page."
>
>
>
> Proposed Change:
> Need clarification. Please explain them by using more plain words.
>
>

================================
Response from the Working Group
================================
Thank you

we have added examples under each statement to make it clearer.

It now reads

"If the background or the letters vary in relative luminance (or are
patterned), then the background around the letters can be chosen or
shaded so that the letters maintain a 4.5:1 contrast ratio with the
background behind them even if they do not have that contrast ratio
with the entire background.

For example, if a letter is lighter at the top than it is a the
bottom, it may be difficult to maintain the contrast ratio between the
letter and the background over the full letter. In this case, the
designer might darken the background behind the letter, or a thin
black outline (at least one pixel wide) around the letter in order to
keep the contrast ratio between the letter and the background above
4.5:1.

The contrast ratio can sometimes be maintained by changing the
relative luminance of the letters as the relative luminance of the
background changes across the page.

For example, if a page is very light on one edge and fades to very
dark on the other edge, there is no color that can run across the page
and meet the contrast guidelines on both edges. One way of addressing
this would be to change the lightness of the letters as well so that
each letter always meets the contrast ratio for the background that is
immediately behind the letter."

Loretta Guarino Reid, WCAG WG Co-Chair
Gregg Vanderheiden, WCAG WG Co-Chair
Michael Cooper, WCAG WG Staff Contact


On behalf of the WCAG Working Group
Received on Saturday, 24 April 2010 01:39:52 UTC

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