added ‘perceived’ to luminance.

understanding/21/non-text-contrast.html

@@ -38,7 +38,7 @@ <h4>Adjacent colors</h4>
 					<figcaption>A standard text input with white adjacent color outside the component</figcaption>
 				</figure>
 
-				<p>If components use several colors, any color which does not interfere with identifying the component can be ignored for the purpose of measuring contrast ratio. For example, a 3D drop-shadow on an input, or a dark border line between contrasting backgrounds is considered to be subsumed into the color closest in brightness (luminance).</p>
+				<p>If components use several colors, any color which does not interfere with identifying the component can be ignored for the purpose of measuring contrast ratio. For example, a 3D drop-shadow on an input, or a dark border line between contrasting backgrounds is considered to be subsumed into the color closest in brightness (perceived luminance).</p>
 
 				<p>The following example shows an input that has a light background on the inside and a dark background around it. The input also has a dark grey border which is considered to be subsumed into the dark background. The border does not interfere with identifying the component, so the contrast ratio is taken between the white background and dark blue background.</p>