[css-color-hdr] Added dynamic-range-limit property, w3c#9074

Author: svgeesus

css-color-hdr/Overview.bs

@@ -169,7 +169,51 @@ Introducing Headroom {#introducing-headroom}
 	to allow meaningful evaluation of the group of photos.
 </div>
 
-
+The 'dynamic-range-limit' property {#the-dynamic-range-limit-property}
+-------------------------------
+	
+		<pre class='propdef'>
+			Name: dynamic-range-limit
+			Value: standard | high | constrained-high
+			Initial: high
+			Applies to: all elements
+			Inherited: no
+			Percentages: n/a
+			Computed value: specified value
+			Animation type: by computed value type 
+			Canonical order: per grammar
+		</pre>
+	
+		<dl dfn-type="value" dfn-for="dynamic-range-limit">
+			<dt><dfn>standard</dfn>
+			<dd>
+				The highest luminance color
+				that is displayed is the same as '
+				media white, i.e. the CSS color ''white''.
+			</dd>
+			<dt><dfn>high</dfn>
+			<dd>
+				The highest peak luminance
+				that is displayed is much greater than
+				media white, i.e. the CSS color ''white'';
+				the precise level is not specified.
+			</dd>
+			<dt><dfn>constrained-high</dfn>
+			<dd>
+				The highest peak luminance
+				that is displayed is somewhat greater than
+				media white, i.e. the CSS color ''white'',
+				such that a mix of SDR and HDR content
+				can be comfortably viewed together.
+			</dd>	
+		</dl>
+
+		<div class="example" id="ex-hdr-limit-photogrid">
+			<pre class="lang-css">
+				body { dynamic-range-limit: standard; }
+				div.photogrid img { dynamic-range-limit: constrained-high }
+			</pre>
+		</div>
 
 Predefined color spaces for HDR: {#predefined-HDR}
 =====================