added option to reset an "empty" image

src/Intervention/Image/Image.php

@@ -70,6 +70,13 @@ class Image
      */
     protected $filesystem;
 
+    /**
+     * Attributes of the original created image
+     * 
+     * @var Array
+     */
+    protected $original;
+
     /**
      * Create a new instance of Image class
      *
@@ -152,6 +159,9 @@ class Image
             $this->width = is_numeric($width) ? intval($width) : 1;
             $this->height = is_numeric($height) ? intval($height) : 1;
 
+            $this->original['width'] = $this->width;
+            $this->original['height'] = $this->height;
+
             // create empty image
             $this->resource = @imagecreatetruecolor($this->width, $this->height);
 
@@ -593,7 +603,14 @@ class Image
      */
     public function reset()
     {
+        if (is_null($this->dirname) && is_null($this->basename)) {
+            
+            $this->setProperties(null, $this->original['width'], $this->original['height']);
+
+        } else {
+
             $this->setProperties($this->dirname .'/'. $this->basename);
+        }
 
         return $this;
     }

tests/ImageTest.php

@@ -290,6 +290,17 @@ class ImageTest extends PHPUnit_Framework_Testcase
         $this->assertEquals($img->height, 600);
     }
 
+    public function testResetEmptyImage()
+    {
+        $img = new Image(null, 800, 600);
+        $img->resize(300, 200);
+        $img->reset();
+        $this->assertInternalType('int', $img->width);
+        $this->assertInternalType('int', $img->height);
+        $this->assertEquals($img->width, 800);
+        $this->assertEquals($img->height, 600);
+    }
+
     public function testSaveImage()
     {
         $save_as = 'public/test2.jpg';