Removing need for an image rendition required by wagtail out the box, by reusing and shrinking another.

wagtail/wagtailadmin/static_src/wagtailadmin/scss/components/forms.scss

@@ -871,8 +871,19 @@ ul.inline li:first-child, li.inline:first-child{
         }
         .preview-image{
             float:left;
-            margin-left:-($thumbnail-width);
-            margin-right:1em;
+            margin-left: -($thumbnail-width);
+            margin-right: 1em;
+            max-width: $thumbnail-width;
+
+            // Resize standard Wagtail thumbnail size (165x165) to 130 for space-saving purposes.
+            // We could request a 130x130 rendition, but that's just unnecessary and burdens installations
+            // where images are store off-site with higher rendering times.
+            img{
+                max-width: $thumbnail-width;
+                max-height: $thumbnail-width;
+                height: auto;
+                width: auto;
+            }
         }
     }
 }

wagtail/wagtailimages/templates/wagtailimages/widgets/image_chooser.html

@@ -6,7 +6,7 @@
 {% block chosen_state_view %}
     <div class="preview-image">
         {% if image %}
-            {% image image max-130x130 %}
+            {% image image max-165x165 %}
         {% else %}
             <img>
         {% endif %}

wagtail/wagtailimages/views/chooser.py

@@ -19,7 +19,7 @@ def get_image_json(image):
     helper function: given an image, return the json to pass back to the
     image chooser panel
     """
-    preview_image = image.get_rendition('max-130x100')
+    preview_image = image.get_rendition('max-165x165')
 
     return json.dumps({
         'id': image.id,