Refactoring with use of separate to sub classes from Image. Add FileHelper to trying toString conversion. Add ImageCollection (not tested work).

ImageCollection.class.php

@@ -0,0 +1,34 @@
+<?php
+
+abstract class ImageCollection extends ArrayIterator
+{
+    /**
+     * @var string
+     */
+    protected $class;
+
+    /**
+     * @param array $data
+     * @throws ErrorException
+     */
+    public function __construct($data)
+    {
+        /**
+         * @var $class Image
+         */
+        $class = $this->class;
+        Image::checkSubClass($class);
+        if (is_null($data) || $data == '') {
+            throw new ErrorException('Empty data.');
+        }
+        if (!is_array($data)) {
+            $data = json_decode($data, true);
+            if (json_last_error() != JSON_ERROR_NONE) {
+                throw new ErrorException('Unable to convert json-string to array.');
+            }
+        }
+        foreach ($data as $item_data) {
+            $this->append($class::getInstance($item_data));
+        }
+    }
+}