Update to Drupal 8.0.0-beta15. For more information, see: https://www.drupal.org/node/2563023

core/modules/image/migration_templates/d6_imagecache_presets.yml

@@ -0,0 +1,24 @@
+id: d6_imagecache_presets
+label: Drupal 6 ImageCache Presets
+migration_tags:
+  - Drupal 6
+source:
+  plugin: d6_imagecache_presets
+process:
+  name:
+    -
+      plugin: machine_name
+      source: presetname
+    -
+      plugin: dedupe_entity
+      entity_type: image_style
+      field: name
+      length: 32
+  label: presetname
+  effects:
+    plugin: d6_imagecache_actions
+    source:
+      - @plugin
+      - data
+destination:
+  plugin: entity:image_style

core/modules/image/migration_templates/d7_image_settings.yml

@@ -0,0 +1,16 @@
+id: d7_image_settings
+migration_tags:
+  - Drupal 7
+source:
+  plugin: variable
+  variables:
+    - allow_insecure_derivatives
+    - suppress_itok_output
+    - image_style_preview_image
+process:
+  suppress_itok_output: suppress_itok_output
+  allow_insecure_derivatives: allow_insecure_derivatives
+  preview_image: image_style_preview_image
+destination:
+  plugin: config
+  config_name: image.settings