Skip to content
New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Jump to bottom

Alternative update for red-flash note #2619

Closed
wants to merge 8 commits into from
Closed

Alternative update for red-flash note #2619

Show file tree
Hide file tree
Changes from all commits
Commits
Show all changes
8 commits
Select commit Hold shift + click to select a range
2763bba
Update general-flash-and-red-flash-thresholds.html
rachaelbradley Aug 4, 2022
ddae8ca
editorial change
rachaelbradley Aug 4, 2022
4495539
Flash - Updates from the meeting
alastc Aug 10, 2022
996e657
Reverting note 3
alastc Aug 10, 2022
fd953f5
Adding smaller note plus understanding update
alastc Aug 15, 2022
02c65a7
Highlighting the updated working def
alastc Aug 15, 2022
85ee668
Removing the non-red flash bits.
alastc Aug 16, 2022
1ca98d1
Removing the non-red-flash bits
alastc Aug 16, 2022
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
2 changes: 2 additions & 0 deletions guidelines/terms/20/general-flash-and-red-flash-thresholds.html
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -49,6 +49,8 @@
of two opposing transitions.
</p>

<p class="note">The new working definition in the field for <strong>"pair of opposing transitions involving a saturated red"</strong> (from WCAG 2.2) is a pair of opposing transitions where, one transition is either to or from a state with a value R/(R + G + B) that is greater than or equal to 0.8, and the difference between states is more than 0.2 (unitless) in the CIE 1976 UCS chromaticity diagram. [ISO 9241-391] </p>

<p class="note">The current working definition in the field for <strong>"pair of opposing transitions involving a saturated red"</strong> is where, for either or both states involved in each transition, R/(R+ G + B) &gt;=
0.8, and the change in the value of (R-G-B)x320 is &gt; 20 (negative values of (R-G-B)x320
are set to zero) for both transitions. R, G, B values range from 0-1 as specified
Expand Down
20 changes: 20 additions & 0 deletions understanding/20/three-flashes-or-below-threshold.html
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -76,6 +76,26 @@ <h2>Intent of Three Flashes or Below Threshold</h2>
</ul>

</div>

<div class="note">
<p>The new (in WCAG 2.2) working definition in the field for <strong>"pair of opposing transitions involving a saturated red"</strong> is a pair of opposing transitions where, one transition is either to or from a state with a value R/(R + G + B) that is greater than or equal to 0.8, and the difference between states is more than 0.2 (unitless) in the CIE 1976 UCS chromaticity diagram. [ISO 9241-391] </p>
<p>The chromaticity difference is calculated as:</p>
<ul>
<li><code>SQRT( (u'1 - u'2)^2 + (v'1 - v'2)^2 )</code></li>
</ul>
<p>where u'1 and v'1 are chromaticity coordinates of State 1 and u'2 and v'2 are chromaticity coordinates of State 2. The 1976 UCS chromaticity coordinates of u' and v' are calculated as:</p>
<ul>
<li><code>u' = 4 * X / (X + 15 * Y + 3 * Z)</code></li>
<li><code>v' = 9 * Y / (X + 15 * Y + 3 * Z)</code></li>
</ul>
<p>where X, Y, and Z are the tristimulus values of a color in the CIE XYZ colorspace, which can be calculated as:</p>
<ul>
<li><code>X = 0.4124564 * R + 0.3575761 * G + 0.1804375 * B</code></li>
<li><code>Y = 0.2126729 * R + 0.7151522 * G + 0.0721750 * B</code></li>
<li><code>Z = 0.0193339 * R + 0.1191920 * G + 0.9503041 * B</code></li>
</ul>
<p>where R, G, & B are values that range from 0-1 as specified in “relative luminance” definition. </p>
</div>


</section>
Expand Down