Update to drupal 8.0.0-rc1. For more information, see https://www.drupal.org/node/2582663

core/modules/image/migration_templates/d6_imagecache_presets.yml

@@ -1,5 +1,5 @@
 id: d6_imagecache_presets
-label: Drupal 6 ImageCache Presets
+label: ImageCache Presets
 migration_tags:
   - Drupal 6
 source:
@@ -18,7 +18,7 @@ process:
   effects:
     plugin: d6_imagecache_actions
     source:
-      - @plugin
+      - '@plugin'
       - data
 destination:
   plugin: entity:image_style

core/modules/image/migration_templates/d7_image_settings.yml

@@ -1,4 +1,5 @@
 id: d7_image_settings
+label: Image configuration
 migration_tags:
   - Drupal 7
 source:

core/modules/image/migration_templates/d7_image_styles.yml

@@ -0,0 +1,18 @@
+id: d7_image_styles
+label: Image styles
+migration_tags:
+  - Drupal 7
+source:
+  plugin: d7_image_styles
+process:
+  name: name
+  label: label
+  effects:
+    plugin: iterator
+    source: effects
+    process:
+      id: name
+      weight: weight
+      data: data
+destination:
+  plugin: entity:image_style