[cAdded new section, sample code for color conversions #9934

Author: svgeesus

css-color-hdr-1/Overview.bs

@@ -99,8 +99,7 @@ WPT Display: open
 		"What_is_ICtCp": {
 			"href": "https://professional.dolby.com/siteassets/pdfs/ictcp_dolbywhitepaper_v071.pdf",
 			"title": "What is ICtCp, v7.1",
-			"publisher": "Dolby",
-
+			"publisher": "Dolby"
 		}
 	}
 </pre>
@@ -890,7 +889,7 @@ Converting JzCzHz colors to Jzazbz  colors</h4>
 	the Hunt-Pointer-Estevez (HPE) XYZ to LMS transform
 	is used,
 	normalized to a [=D65=] whitepoint.
-	A crosstalk matrix is then applied,
+	A 4% crosstalk matrix is then applied  [[What_is_ICtCp]],
 	to reduce the gamut hull concavities of BT.2020 RGB,
 	thus reducing interpolation errors.
 	The crosstalk also provides improved lines of constant hue
@@ -921,11 +920,12 @@ Converting JzCzHz colors to Jzazbz  colors</h4>
 	by a conversion from linear-light BT.2100 RGB [[Rec_BT.2100]],
 	this conversion proceeds via LMS
 	and thus, any other color space can also be represented
-	by applying an XYZ to LMS transform.
+	by applying an XYZ to LMS transform
+	as shown in [[What_is_ICtCp]].
 
-	Note that unlike Lab, a [=D65=] whitepoint is used.
+	Note that unlike CIE ''Lab'', a [=D65=] whitepoint is used.
 
-	Also unlike Lab, which has primarily been tested with
+	Also unlike ''Lab'', which has primarily been tested with
 	lower-intensity reflective colors,
 	IC<sub>T</sub>C<sub>P</sub> has been tested with
 	high-chroma,
@@ -1034,6 +1034,29 @@ Serializing values of the ''color()'' function</h3>
 	is recommended for internal storage).
 	Values must be <a href="https://drafts.csswg.org/css-values-4/#combine-integers">rounded towards +∞</a>, not truncated.
 
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+
+<h2 id="color-conversion-code">
+	Sample code for Color Conversions</h2>
+	
+	<em>This section is not normative.</em>
+	<wpt title="This section is not normative, it does not need tests."></wpt>
+	
+	
+	For clarity, <a href="https://drafts.csswg.org/css-color-4/multiply-matrices.js">a library</a> is used for matrix multiplication.
+	(This is more readable than inlining all the multiplies and adds).
+	The matrices are in <a href="https://www.scratchapixel.com/lessons/mathematics-physics-for-computer-graphics/geometry/row-major-vs-column-major-vector">column-major order</a>.
+	
+	This code also assumes all of the conversion code from
+	[[css-color-4#color-conversion-code]] is available.
 
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