diff --git a/docs/reference/ImageEnhance.rst b/docs/reference/ImageEnhance.rst
index b27228ec9..746f18cd2 100644
--- a/docs/reference/ImageEnhance.rst
+++ b/docs/reference/ImageEnhance.rst
@@ -29,6 +29,8 @@ Classes
 All enhancement classes implement a common interface, containing a single
 method:
 
+.. _enhancement-factor:
+
 .. py:class:: _Enhance
 
     .. py:method:: enhance(factor)
@@ -45,31 +47,33 @@ method:
 
     Adjust image color balance.
 
-    This class can be used to adjust the colour balance of an image, in
-    a manner similar to the controls on a colour TV set. An enhancement
-    factor of 0.0 gives a black and white image. A factor of 1.0 gives
-    the original image.
+    This class can be used to adjust the colour balance of an image, in a
+    manner similar to the controls on a colour TV set. An
+    :ref:`enhancement factor <enhancement-factor>` of 0.0 gives a black and
+    white image. A factor of 1.0 gives the original image.
 
 .. py:class:: Contrast(image)
 
     Adjust image contrast.
 
-    This class can be used to control the contrast of an image, similar
-    to the contrast control on a TV set. An enhancement factor of 0.0
-    gives a solid grey image. A factor of 1.0 gives the original image.
+    This class can be used to control the contrast of an image, similar to the
+    contrast control on a TV set. An
+    :ref:`enhancement factor <enhancement-factor>` of 0.0 gives a solid grey
+    image. A factor of 1.0 gives the original image.
 
 .. py:class:: Brightness(image)
 
     Adjust image brightness.
 
-    This class can be used to control the brightness of an image.  An
-    enhancement factor of 0.0 gives a black image. A factor of 1.0 gives the
-    original image.
+    This class can be used to control the brightness of an image. An
+    :ref:`enhancement factor <enhancement-factor>` of 0.0 gives a black image.
+    A factor of 1.0 gives the original image.
 
 .. py:class:: Sharpness(image)
 
     Adjust image sharpness.
 
     This class can be used to adjust the sharpness of an image. An
-    enhancement factor of 0.0 gives a blurred image, a factor of 1.0 gives the
-    original image, and a factor of 2.0 gives a sharpened image.
+    :ref:`enhancement factor <enhancement-factor>` of 0.0 gives a blurred
+    image, a factor of 1.0 gives the original image, and a factor of 2.0 gives
+    a sharpened image.