FIX Make sure image backends implement method getImageResource

src/Assets/Image_Backend.php

@@ -49,6 +49,13 @@ interface Image_Backend
      */
     public function loadFrom($path);
 
+    /**
+     * Get the currently assigned image resource
+     *
+     * @return mixed
+     */
+    public function getImageResource();
+
     /**
      * Write to the given asset store
      *

src/Assets/ImagickBackend.php

@@ -22,6 +22,15 @@ class ImagickBackend extends Imagick implements Image_Backend
      */
     private static $default_quality = 75;
 
+    /**
+     * @return $this
+     */
+    public function getImageResource()
+    {
+        // the object represents the resource
+        return $this;
+    }
+
     /**
      * Create a new backend with the given object
      *