diff --git a/index.php b/index.php
index 6804ec4..e43c87a 100755
--- a/index.php
+++ b/index.php
@@ -81,8 +81,8 @@ switch ($mode) {
         break;
     case 'phase':
         $template = 'change.html.twig';
-        $variables['imageWithElement'] = 'img/'.$phase.'-with.jpg';
-        $variables['imageWithoutElement'] = 'img/'.$phase.'-without.jpg';
+        $variables['imageWithElement'] = 'img/'.$phase.'-with.'.$settings->filetype;
+        $variables['imageWithoutElement'] = 'img/'.$phase.'-without.'.$settings->filetype;
         $variables['step_count'] = $index;
 		$variables['step_total'] = count($settings->phases);
 		// Store the participant ID with some simple validation to prevent SQL injection
diff --git a/settings.json.example b/settings.json.example
index 9d5327a..3a79f82 100644
--- a/settings.json.example
+++ b/settings.json.example
@@ -13,5 +13,6 @@
     ],
     "baseURL": "/",
     "debug": false,
-	"timezone": "America/Chicago"
+	"timezone": "America/Chicago",
+	"filetype": "jpg"
 }