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[css-color-4] Corrections for Raytrace GMA #14029 #14080

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Merged
svgeesus merged 1 commit into from
Jun 23, 2026
+10 −7
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[css-color-4] Corrections for Raytrace GMA #14029 #14080

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17 changes: 10 additions & 7 deletions css-color-4/Overview.bs
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Original file line number Diff line number Diff line change
Expand Up @@ -6300,8 +6300,8 @@ Sample Pseudocode for the Ray Trace Gamut Mapping</h4>
<li>if |origin_rgb| is not in gamut
<ul>
<!-- we do, so perform chroma reduction -->
<li>let |low| be 0.0 + 1E-6 <a href="#raytrace-footnote-1"><sup>1</sup></a></li>
<li>let |high| be 1.0 - 1E-6 <a href="#raytrace-footnote-2"><sup>2</sup></a></li>
<li>let |low| be 0.0 + 1E-12 <a href="#raytrace-footnote-1"><sup>1</sup></a></li>
<li>let |high| be 1.0 - 1E-12 <a href="#raytrace-footnote-2"><sup>2</sup></a></li>
<li>let |last| be |origin_rgb|</li>
<li>for (i=0; i&lt;4; i++)
<ul>
Expand Down Expand Up @@ -6339,7 +6339,7 @@ Sample Pseudocode for the Ray Trace Gamut Mapping</h4>
<li>let clip(|color|) be a function which converts |color| to |destination|,
clamps each component to the bounds of the reference range for that component
and returns the result</li>
<li>set |clipped| to clip(|current|)</li>
<li>set |clipped| to clip(|origin_rgb|)</li>
<li>return |clipped| as the gamut mapped color</li>
</ol>

Expand All @@ -6366,7 +6366,7 @@ Sample Pseudocode for the Ray Trace Gamut Mapping</h4>
<li>let |d| be |b| - |a|</li>
<li>let |direction| <i>[i]</i> be |d|</li>
<!-- Non parallel cases -->
<li>if abs(|d|) < 1E-12
<li>if abs(|d|) > 1E-12 <a href="#raytrace-footnote-7"><sup>7</sup></a></li>
<ul>
<li>let |inv_d| be 1 / |d|</li>
<li>let |t1| be (|bmin| <i>[i]</i> - |a| ) * |inv_d| </li>
Expand All @@ -6392,7 +6392,7 @@ Sample Pseudocode for the Ray Trace Gamut Mapping</h4>
<li>if |tnear| &lt; 0
<ul>
<li>let |tnear| be |tfar|
<a href="#raytrace-footnote-7"><sup>7</sup></a>
<a href="#raytrace-footnote-8"><sup>8</sup></a>
</li>
</ul>
</li>
Expand All @@ -6416,7 +6416,7 @@ Sample Pseudocode for the Ray Trace Gamut Mapping</h4>
It is assumed the minimum value is 0
and that all channels have the same minimum.
The value should be small relative to the unit type.
64 bit could easily be as small as 1e-14, but 1e-6 is fine in practice.</li>
The specifed value of 1e-12 is for 64-bit, but for 32-bit, 1e-6 should be used.</li>
<li id="raytrace-footnote-2">
1.0 represents the maximum in-gamut channel value,
and it is assumed all channels have the same maximum.</li>
Expand All @@ -6438,7 +6438,10 @@ Sample Pseudocode for the Ray Trace Gamut Mapping</h4>
this simplifies to a single constant
rather than a 3-element array.</li>
<li id="raytrace-footnote-7">
favoring the first intersection in the direction |start| -> |end| .
The value should be small relative to the unit type.
The specifed value of 1e-12 is for 64-bit, but for 32-bit, 1e-6 should be used.</li>
<li id="raytrace-footnote-8">
favoring the first intersection in the direction |start| -> |end| .</li>
</ol>

</div>
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