Minor changes

doc/image3.html

@@ -538,7 +538,7 @@ <h4>Arguments</h4>
       <dt>channel</dt>
 
       <dd>A <a href="constants.html#ChannelType">ChannelType</a>
-      constant. The default is to operate on all channels.</dd>
+      value. The default is to operate on all channels.</dd>
     </dl>
 
     <h4>Returns</h4>
@@ -1168,7 +1168,7 @@ <h4>Arguments</h4>
 
       <dd>A <a href=
       "constants.html#ColorspaceType"><code>ColorspaceType</code></a>
-      constant. <span class="imquote">Empirical evidence suggests
+      value. <span class="imquote">Empirical evidence suggests
       that distances in YUV or YIQ correspond to perceptual color
       differences more closely than do distances in RGB space. The
       image is then returned to RGB colorspace after color
@@ -2563,7 +2563,7 @@ <h4>Arguments</h4>
       <dt>opacity</dt>
 
       <dd>The new opacity value, either an <a href=
-      "constants.html#Opacity">opacity</a> constant or a number
+      "constants.html#Opacity">opacity</a> value or a number
       between 0 and MaxRGB. The default is TransparentOpacity.</dd>
     </dl>