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Updating the contrast value #1780

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Updating the contrast value #1780

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b96c69b
Updating the contrast value
alastc May 4, 2021
a5b25bf
Rain's suggested wording
alastc May 11, 2021
e828fad
removing the SRGB reference
alastc May 11, 2021
1fa788a
Meeting updates.
alastc May 11, 2021
fce0993
Aligned understandings docs
alastc May 13, 2021
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12 changes: 0 additions & 12 deletions biblio.js
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Expand Up @@ -31,18 +31,6 @@ respecConfig.localBiblio = {
"publisher": "International Standards Organization"
},

"sRGB": {
"authors": [
"M. Stokes",
"M. Anderson",
"S. Chandrasekar",
"R. Motta"
],
"date": "November 5, 1996",
"href": "https://www.w3.org/Graphics/Color/sRGB.html",
"title": "A Standard Default Color Space for the Internet - sRGB, Version 1.10"
},

"UNESCO": {
"date": "1997",
"href": "http://www.unesco.org/education/information/nfsunesco/doc/isced_1997.htm",
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10 changes: 6 additions & 4 deletions guidelines/terms/20/relative-luminance.html
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Expand Up @@ -12,13 +12,13 @@

<ul>

<li>if RsRGB &lt;= 0.03928 then <strong>R</strong> = RsRGB/12.92 else <strong>R</strong> = ((RsRGB+0.055)/1.055) ^ 2.4
<li>if RsRGB &lt;= 0.04045 then <strong>R</strong> = RsRGB/12.92 else <strong>R</strong> = ((RsRGB+0.055)/1.055) ^ 2.4
</li>

<li>if GsRGB &lt;= 0.03928 then <strong>G</strong> = GsRGB/12.92 else <strong>G</strong> = ((GsRGB+0.055)/1.055) ^ 2.4
<li>if GsRGB &lt;= 0.04045 then <strong>G</strong> = GsRGB/12.92 else <strong>G</strong> = ((GsRGB+0.055)/1.055) ^ 2.4
</li>

<li>if BsRGB &lt;= 0.03928 then <strong>B</strong> = BsRGB/12.92 else <strong>B</strong> = ((BsRGB+0.055)/1.055) ^ 2.4
<li>if BsRGB &lt;= 0.04045 then <strong>B</strong> = BsRGB/12.92 else <strong>B</strong> = ((BsRGB+0.055)/1.055) ^ 2.4
</li>

</ul>
Expand All @@ -35,11 +35,13 @@

</ul>

<p>The "^" character is the exponentiation operator. (Formula taken from [[sRGB]] and
<p>The "^" character is the exponentiation operator. (Formula taken from
[[IEC-4WD]]).
</p>

</div>

<p class="note">Before May 2021 the value of 0.04045 in the definition was different (0.03928). It was taken from an older version of the specification and has been updated. It has no practical effect on the calculations in the context of these guidelines.</p>

<p class="note">Almost all systems used today to view Web content assume sRGB encoding. Unless it
is known that another color space will be used to process and display the content,
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7 changes: 4 additions & 3 deletions techniques/general/G145.html
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Expand Up @@ -52,7 +52,7 @@
<ul>
<li>if R
sRGB
&lt;= 0.03928 then
&lt;= 0.04045 then
<strong>R</strong>
= R
sRGB
Expand All @@ -63,7 +63,7 @@
+0.055)/1.055) ^ 2.4</li>
<li>if G
sRGB
&lt;= 0.03928 then
&lt;= 0.04045 then
<strong>G</strong>
= G
sRGB
Expand All @@ -74,7 +74,7 @@
+0.055)/1.055) ^ 2.4</li>
<li>if B
sRGB
&lt;= 0.03928 then
&lt;= 0.04045 then
<strong>B</strong>
= B
sRGB
Expand Down Expand Up @@ -146,6 +146,7 @@
<li>#4 is true</li>
</ul>
</section>
<p class="note">Before May 2021 the value of 0.04045 in the definition was different (0.03928). It was taken from an older version of the specification and has been updated. It has no practical effect on the calculations in the context of these guidelines.</p>
</section><section id="related"><h2>Related Techniques</h2></section><section id="resources"><h2>Resources</h2>

<ul>
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7 changes: 4 additions & 3 deletions techniques/general/G17.html
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Expand Up @@ -53,7 +53,7 @@
<ul>
<li>if R
sRGB
&lt;= 0.03928 then
&lt;= 0.04045 then
<strong>R</strong>
= R
sRGB
Expand All @@ -64,7 +64,7 @@
+0.055)/1.055) ^ 2.4</li>
<li>if G
sRGB
&lt;= 0.03928 then
&lt;= 0.04045 then
<strong>G</strong>
= G
sRGB
Expand All @@ -75,7 +75,7 @@
+0.055)/1.055) ^ 2.4</li>
<li>if B
sRGB
&lt;= 0.03928 then
&lt;= 0.04045 then
<strong>B</strong>
= B
sRGB
Expand Down Expand Up @@ -147,6 +147,7 @@
<li>#4 is true</li>
</ul>
</section>
<p class="note">Before May 2021 the value of 0.04045 in the definition was different (0.03928). It was taken from an older version of the specification and has been updated. It has no practical effect on the calculations in the context of these guidelines.</p>
</section><section id="related"><h2>Related Techniques</h2><ul>
<li><a href="../general/G148">G148</a></li>
<li><a href="../general/G174">G174</a></li>
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7 changes: 4 additions & 3 deletions techniques/general/G18.html
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Expand Up @@ -58,7 +58,7 @@
<ul>
<li>if R
sRGB
&lt;= 0.03928 then
&lt;= 0.04045 then
<strong>R</strong>
= R
sRGB
Expand All @@ -69,7 +69,7 @@
+0.055)/1.055) ^ 2.4</li>
<li>if G
sRGB
&lt;= 0.03928 then
&lt;= 0.04045 then
<strong>G</strong>
= G
sRGB
Expand All @@ -80,7 +80,7 @@
+0.055)/1.055) ^ 2.4</li>
<li>if B
sRGB
&lt;= 0.03928 then
&lt;= 0.04045 then
<strong>B</strong>
= B
sRGB
Expand Down Expand Up @@ -152,6 +152,7 @@
<li>#4 is true.</li>
</ul>
</section>
<p class="note">Before May 2021 the value of 0.04045 in the definition was different (0.03928). It was taken from an older version of the specification and has been updated. It has no practical effect on the calculations in the context of these guidelines.</p>
</section><section id="related"><h2>Related Techniques</h2></section><section id="resources"><h2>Resources</h2>

<ul>
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4 changes: 2 additions & 2 deletions understanding/20/contrast-enhanced.html
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Expand Up @@ -163,13 +163,13 @@ <h3>Rationale for the Ratios Chosen</h3>

<h3>Notes on formula</h3>

<p>Conversion from nonlinear to linear RGB values is based on IEC/4WD 61966-2-1 [[IEC-4WD]] and on "A Standard Default Color Space for the Internet - sRGB" [[sRGB]].</p>
<p>Conversion from nonlinear to linear RGB values is based on IEC/4WD 61966-2-1 [[IEC-4WD]].</p>

<p>The formula (L1/L2) for contrast is based on [[ISO-9241-3]] and [[ANSI-HFES-100-1988]] standards.</p>

<p>The ANSI/HFS 100-1988 standard calls for the contribution from ambient light to be
included in the calculation of L1 and L2. The .05 value used is based on Typical Viewing
Flare from [[IEC-4WD]] and the [[sRGB]] paper by M. Stokes et al.
Flare from [[IEC-4WD]].
</p>

<p>This Success Criterion and its definitions use the terms "contrast ratio" and "relative
Expand Down
4 changes: 2 additions & 2 deletions understanding/20/contrast-minimum.html
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Expand Up @@ -223,13 +223,13 @@ <h3>Rationale for the Ratios Chosen</h3>

<h3>Notes on formula</h3>

<p>Conversion from nonlinear to linear RGB values is based on IEC/4WD 61966-2-1 [[IEC-4WD]] and on "A Standard Default Color Space for the Internet - sRGB" [[sRGB]].</p>
<p>Conversion from nonlinear to linear RGB values is based on IEC/4WD 61966-2-1 [[IEC-4WD]].</p>

<p>The formula (L1/L2) for contrast is based on [[ISO-9241-3]] and [[ANSI-HFES-100-1988]] standards.</p>

<p>The ANSI/HFS 100-1988 standard calls for the contribution from ambient light to be
included in the calculation of L1 and L2. The .05 value used is based on Typical Viewing
Flare from [[IEC-4WD]] and the [[sRGB]] paper by M. Stokes et al.
Flare from [[IEC-4WD]].
</p>

<p>This Success Criterion and its definitions use the terms "contrast ratio" and "relative
Expand Down