Add release notes for image feature detection

CHANGELOG.txt

@@ -4,6 +4,7 @@ Changelog
 0.5 (xx.xx.20xx)
 ~~~~~~~~~~~~~~~~
  * Added multiple image uploader
+ * Added support for face and feature detection on images using the OpenCV library
  * Added RoutablePage model to allow embedding Django-style URL routing within a page
  * Explorer nav now rendered separately and fetched with AJAX when needed
  * Added decorator syntax for hooks

docs/core_components/images/feature_detection.rst

@@ -1,3 +1,5 @@
+.. _image_feature_detection:
+
 =================
 Feature Detection
 =================

docs/releases/0.5.rst

@@ -16,6 +16,14 @@ Multiple image uploader
 The image uploader UI has been improved to allow multiples to be uploaded quickly.
 
 
+Image feature detection
+~~~~~~~~~~~~~~~~~~~~~~~
+
+Wagtail can now apply face and feature detection on images using `OpenCV <http://opencv.org/>`_, and use this to intelligently crop images.
+
+:ref:`image_feature_detection`
+
+
 RoutablePage
 ~~~~~~~~~~~~
 
@@ -58,8 +66,17 @@ Bug fixes
  * Updates to tag fields are now properly committed to the database when publishing directly from the page edit interface.
 
 
-Backwards incompatible changes
-==============================
+Upgrade considerations
+======================
+
+New fields on Image and Rendition models
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+Several new fields have been added to the Image and Rendition models to support :ref:`image_feature_detection`. These will be added to the database when you run ``./manage.py migrate``. If you have defined a custom image model (by extending the ``wagtailimages.AbstractImage`` and ``wagtailimages.AbstractRendition`` classes and specifying ``WAGTAILIMAGES_IMAGE_MODEL`` in settings), the change needs to be applied to that model's database table too. Running the command::
+
+  ./manage.py schemamigration myapp --auto add_image_focal_point_fields``
+
+(with 'myapp' replaced with your app name) will generate the necessary migration file.
 
 
 Deprecated features