diff --git a/includes/bootstrap.inc b/includes/bootstrap.inc
index 80563ef..d194319 100644
--- a/includes/bootstrap.inc
+++ b/includes/bootstrap.inc
@@ -218,12 +218,16 @@ define('LANGUAGE_RTL', 1);
 define('REQUEST_TIME', (int) $_SERVER['REQUEST_TIME']);
 
 /**
- * Flag for drupal_set_title(); text is not sanitized, so run check_plain().
+ * Flag used to indicate that text is not sanitized, so run check_plain().
+ *
+ * @see drupal_set_title()
  */
 define('CHECK_PLAIN', 0);
 
 /**
- * Flag for drupal_set_title(); text has already been sanitized.
+ * Flag used to indicate that text has already been sanitized.
+ *
+ * @see drupal_set_title()
  */
 define('PASS_THROUGH', -1);
 
diff --git a/modules/image/image.admin.inc b/modules/image/image.admin.inc
index f6d8e68..7e62621 100644
--- a/modules/image/image.admin.inc
+++ b/modules/image/image.admin.inc
@@ -313,7 +313,7 @@ function image_style_name_validate($element, $form_state) {
 function image_style_delete_form($form, &$form_state, $style) {
   $form_state['image_style'] = $style;
 
-  $replacement_styles = array_diff_key(image_style_options(), array($style['name'] => ''));
+  $replacement_styles = array_diff_key(image_style_options(TRUE, PASS_THROUGH), array($style['name'] => ''));
   $form['replacement'] = array(
     '#title' => t('Replacement style'),
     '#type' => 'select',
diff --git a/modules/image/image.field.inc b/modules/image/image.field.inc
index 60c0f5a..2354738 100644
--- a/modules/image/image.field.inc
+++ b/modules/image/image.field.inc
@@ -311,7 +311,7 @@ function image_field_widget_settings_form($field, $instance) {
   $form['preview_image_style'] = array(
     '#title' => t('Preview image style'),
     '#type' => 'select',
-    '#options' => image_style_options(FALSE),
+    '#options' => image_style_options(FALSE, PASS_THROUGH),
     '#empty_option' => '<' . t('no preview') . '>',
     '#default_value' => $settings['preview_image_style'],
     '#description' => t('The preview image will be shown while editing the content.'),
@@ -495,7 +495,7 @@ function image_field_formatter_settings_form($field, $instance, $view_mode, $for
   $display = $instance['display'][$view_mode];
   $settings = $display['settings'];
 
-  $image_styles = image_style_options(FALSE);
+  $image_styles = image_style_options(FALSE, PASS_THROUGH);
   $element['image_style'] = array(
     '#title' => t('Image style'),
     '#type' => 'select',
@@ -528,7 +528,7 @@ function image_field_formatter_settings_summary($field, $instance, $view_mode) {
 
   $summary = array();
 
-  $image_styles = image_style_options(FALSE);
+  $image_styles = image_style_options(FALSE, PASS_THROUGH);
   // Unset possible 'No defined styles' option.
   unset($image_styles['']);
   // Styles could be lost because of enabled/disabled modules that defines
diff --git a/modules/image/image.module b/modules/image/image.module
index cb9938c..fcbf62c 100644
--- a/modules/image/image.module
+++ b/modules/image/image.module
@@ -766,18 +766,26 @@ function image_style_effects($style) {
  *
  * @param $include_empty
  *   If TRUE a <none> option will be inserted in the options array.
+ * @param $output
+ *   Optional flag determining how the options will be sanitized on output.
+ *   Leave this at the default (CHECK_PLAIN) if you are using the output of
+ *   this function directly in an HTML context, such as for checkbox or radio
+ *   button labels, and do not plan to sanitize it on your own. If using the
+ *   output of this function as select list options (its primary use case), you
+ *   should instead set this flag to PASS_THROUGH to avoid double-escaping of
+ *   the output (the form API sanitizes select list options by default).
  *
  * @return
  *   Array of image styles with the machine name as key and the label as value.
  */
-function image_style_options($include_empty = TRUE) {
+function image_style_options($include_empty = TRUE, $output = CHECK_PLAIN) {
   $styles = image_styles();
   $options = array();
   if ($include_empty && !empty($styles)) {
     $options[''] = t('<none>');
   }
   foreach ($styles as $name => $style) {
-    $options[$name] = $style['label'];
+    $options[$name] = ($output == PASS_THROUGH) ? $style['label'] : check_plain($style['label']);
   }
 
   if (empty($options)) {
diff --git a/modules/user/user.admin.inc b/modules/user/user.admin.inc
index 932c205..6ca330b 100644
--- a/modules/user/user.admin.inc
+++ b/modules/user/user.admin.inc
@@ -406,7 +406,7 @@ function user_admin_settings() {
     $form['personalization']['pictures']['settings']['user_picture_style'] = array(
       '#type' => 'select',
       '#title' => t('Picture display style'),
-      '#options' => image_style_options(TRUE),
+      '#options' => image_style_options(TRUE, PASS_THROUGH),
       '#default_value' => variable_get('user_picture_style', ''),
       '#description' => t('The style selected will be used on display, while the original image is retained. Styles may be configured in the <a href="!url">Image styles</a> administration area.', array('!url' => url('admin/config/media/image-styles'))),
     );