[Docs] Documentation on the image dimension helpers.

doc-src/content/reference/compass/helpers.haml

@@ -22,3 +22,5 @@ layout: core
   * [elements-of-type()](/docs/reference/compass/helpers/display/)
   * [enumerate()](/docs/reference/compass/helpers/enumerate/)
   * [font-files()](/docs/reference/compass/helpers/font-files/)
+  * [image-width()](/docs/reference/compass/helpers/image-dimensions/#image-width)
+  * [image-height()](/docs/reference/compass/helpers/image-dimensions/#image-height)

doc-src/content/reference/compass/helpers/image-dimensions.haml

@@ -0,0 +1,30 @@
+--- 
+title: Compass Image Dimension Helpers
+crumb: Image Dimensions
+framework: compass
+meta_description: Helper functions for working with image dimensions.
+layout: core
+classnames:
+  - reference
+  - core
+  - helpers
+---
+%h1 Compass Image Dimension Helpers
+
+#image-width.helper
+  %h3
+    %a(href="#image-width")
+      image-width(<span class="arg">$image</span>)
+  .details
+    %p
+      Returns the width of the image found at the path supplied by <code>$image</code>
+      relative to your project's images directory.
+
+#image-height.helper
+  %h3
+    %a(href="#image-height")
+      image-height(<span class="arg">$image</span>)
+  .details
+    %p
+      Returns the height of the image found at the path supplied by <code>$image</code>
+      relative to your project's images directory.