[css-color-hdr] Consistently use log (stops) definition of headroom, not linear (multiplier) headroom w3c#11787

Author: svgeesus

css-color-hdr-1/Overview.bs

@@ -563,8 +563,8 @@ Mixing Dynamic Range Limits: the ''dynamic-range-limit-mix()'' function {#dynami
 
 	1. Let <var>c1xyz</var> be <var>c1</var> converted to D65 CIE XYZ
 	2. Let <var>c2xyz</var> be <var>c2</var> converted to D65 CIE XYZ
-	3. Let <var> w1</var> = clamp((log(<var>H</var>) - log(<var>H2</var>)) / (log(<var>H1</var>) - log(<var>H2</var>)), 0, 1)
-	4. Let <var> w2</var> = clamp((log(<var>H</var>) - log(<var>H1</var>)) / (log(<var>H2</var>) - log(<var>H1</var>)), 0, 1)
+	3. Let <var> w1</var> = clamp((<var>H</var> - <var>H2</var>) / (<var>H1</var> - <var>H2</var>), 0, 1)
+	4. Let <var> w2</var> = clamp((<var>H</var> - <var>H1</var>) / (<var>H2</var> - <var>H1</var>), 0, 1)
 		Note that <var> w2</var> = 1 - <var> w1</var>
 	5. Let <var>eps</var> = 0.001 (one JND in linear-light space)
 	6. Let <var>cxyz</var> = pow(<var>c1xyz</var> + <var>eps</var>, <var>w1</var>) * pow(<var>c2xyz</var> + <var>eps</var>, <var>w2</var>) - <var>eps</var>