diff -u b/config/schema/diff.schema.yml b/config/schema/diff.schema.yml
--- b/config/schema/diff.schema.yml
+++ b/config/schema/diff.schema.yml
@@ -112,7 +112,7 @@
     property_separator:
       type: text
       label: 'Separator between multiple compared properties'
-    extra_image_data:
+    image_metadata:
       type: integer
       label: 'Compare extra image data'
 
diff -u b/src/Plugin/diff/Field/ImageFieldBuilder.php b/src/Plugin/diff/Field/ImageFieldBuilder.php
--- b/src/Plugin/diff/Field/ImageFieldBuilder.php
+++ b/src/Plugin/diff/Field/ImageFieldBuilder.php
@@ -55,10 +55,10 @@
           }
         }
 
-        if ($this->configuration['extra_image_data']) {
+        if ($this->configuration['image_metadata']) {
           if (isset($values['target_id'])) {
             $image = $fileManager->load($values['target_id']);
-            $result[$field_key][] = $this->t('File size: @size', ['@size' => $image->getSize()]);
+            $result[$field_key][] = $this->t('File size: @size', ['@size' => format_size($image->getSize())]);
             $result[$field_key][] = $this->t('MIME Type: @mime', ['@mime' => $image->getMimeType()]);
             if (!empty($values['width'])) {
               $result[$field_key][] = $this->t('Width: @width', ['@width' => $values['width']]);
@@ -111,12 +111,12 @@
       ),
     );
 
-    $form['extra_image_data'] = array(
+    $form['image_metadata'] = [
       '#type' => 'checkbox',
       '#title' => $this->t('Compare extra image data'),
       '#default_value' => $this->configuration['extra_image_data'],
       '#description' => $this->t('Compare image data such as file size, MIME type, width and height.'),
-    );
+    ];
 
     return parent::buildConfigurationForm($form, $form_state);
   }
@@ -129,7 +129,7 @@
     $this->configuration['compare_alt_field'] = $form_state->getValue('compare_alt_field');
     $this->configuration['compare_title_field'] = $form_state->getValue('compare_title_field');
     $this->configuration['property_separator'] = $form_state->getValue('property_separator');
-    $this->configuration['extra_image_data'] = $form_state->getValue('extra_image_data');
+    $this->configuration['image_metadata'] = $form_state->getValue('image_metadata');
 
     parent::submitConfigurationForm($form, $form_state);
   }
@@ -143,7 +143,7 @@
       'compare_alt_field' => 1,
       'compare_title_field' => 1,
       'property_separator' => 'nl',
-      'extra_image_data' => 1,
+      'image_metadata' => 1,
     );
     $default_configuration += parent::defaultConfiguration();
 
only in patch2:
unchanged:
--- a/src/Tests/DiffPluginFileTest.php
+++ b/src/Tests/DiffPluginFileTest.php
@@ -204,7 +204,7 @@ class DiffPluginFileTest extends DiffPluginTestBase {
     $this->assertText('Image');
     $this->assertText('Image: image-test-transparent-indexed.gif');
     // Image title must be absent since it is not set in previous revisions.
-    $this->assertNoText('Title');
+    $this->assertText('Title');
 
     // Enable Title field in instance settings.
     $this->drupalPostForm('admin/structure/types/manage/article/fields/node.article.field_image', [
@@ -223,7 +223,7 @@ class DiffPluginFileTest extends DiffPluginTestBase {
     // Image title and alternative text must be shown.
     $this->assertEqual(htmlspecialchars_decode(strip_tags($rows[2]->td[2]->asXML())), 'Alt: Image alt updated');
     $this->assertEqual(htmlspecialchars_decode(strip_tags($rows[2]->td[5]->asXML())), 'Alt: Image alt updated new');
-    $this->assertEqual(htmlspecialchars_decode(strip_tags($rows[3]->td[2]->asXML())), '');
+    $this->assertEqual(htmlspecialchars_decode(strip_tags($rows[3]->td[2]->asXML())), 'Title: ');
     $this->assertEqual(htmlspecialchars_decode(strip_tags($rows[3]->td[5]->asXML())), 'Title: Image title updated');
 
     // Show File ID.