Fix creating new image if file is unchanged.

Adapter/AdapterInterface.php

@@ -377,10 +377,10 @@ public function polygon(array $points, $color, $filled = false);
 
     /**
      * Flips the image.
-     * 
+     *
      * @param int $flipVertical
      * @param int $flipHorizontal
-     * 
+     *
      * @return $this
      */
     public function flip($flipVertical, $flipHorizontal);

Image.php

@@ -617,6 +617,18 @@ public function init()
         $this->getAdapter()->init();
     }
 
+    /**
+     * Determine if image is unchanged / no operations to be performed.
+     *
+     * @param int $quality
+     *
+     * @return bool
+     */
+    protected function isUnchanged($quality)
+    {
+        return empty($this->operations) && $quality == 100;
+    }
+
     /**
      * Save the file to a given output.
      */
@@ -647,6 +659,14 @@ public function save($file, $type = 'guess', $quality = 80)
 
         try {
             $this->init();
+
+            // If the source is a file and it's unchanged just copy it.
+            if ($this->source instanceof \Gregwar\Image\Source\File && $this->isUnchanged($quality)) {
+                copy($this->source->getFile(), $file);
+
+                return $file;
+            }
+
             $this->applyOperations();
 
             $success = false;

tests/ImageTests.php

@@ -141,6 +141,13 @@ public function testNoCache()
         $this->assertNotSame($monalisa, $image->guess());
     }
 
+    public function testImageIsUnchangedWithNoOperations()
+    {
+        $imageFile = __DIR__.'/files/monalisa.jpg';
+        $image = $this->open('monalisa.jpg');
+        $this->assertSame(md5_file($imageFile), md5_file($image->guess(100)));
+    }
+
     public function testActualCache()
     {
         $output = $this->open('monalisa.jpg')