diff --git a/lib/filelib.php b/lib/filelib.php
index aa46e625863..48f8c3632a7 100644
--- a/lib/filelib.php
+++ b/lib/filelib.php
@@ -3612,7 +3612,7 @@ function file_pluginfile($relativepath, $forcedownload, $preview = null) {
             }
 
             // fix file name automatically
-            if ($filename !== 'f1' and $filename !== 'f2') {
+            if ($filename !== 'f1' and $filename !== 'f2' and $filename !== 'f3') {
                 $filename = 'f1';
             }
 
@@ -3625,20 +3625,28 @@ function file_pluginfile($relativepath, $forcedownload, $preview = null) {
                 redirect($theme->pix_url('u/'.$filename, 'moodle')); // intentionally not cached
             }
 
-            if (!$file = $fs->get_file($context->id, 'user', 'icon', 0, '/', $filename.'/.png')) {
-                if (!$file = $fs->get_file($context->id, 'user', 'icon', 0, '/', $filename.'/.jpg')) {
-                    // bad reference - try to prevent future retries as hard as possible!
-                    if ($user = $DB->get_record('user', array('id'=>$context->instanceid), 'id, picture')) {
-                        if ($user->picture == 1 or $user->picture > 10) {
-                            $DB->set_field('user', 'picture', 0, array('id'=>$user->id));
+            if (!$file = $fs->get_file($context->id, 'user', 'icon', 0, '/', $filename.'.png')) {
+                if (!$file = $fs->get_file($context->id, 'user', 'icon', 0, '/', $filename.'.jpg')) {
+                    if ($filename === 'f3') {
+                        // f3 400x400px was introduced in 2.3, there might be only the smaller version.
+                        if (!$file = $fs->get_file($context->id, 'user', 'icon', 0, '/', 'f1.png')) {
+                            $file = $fs->get_file($context->id, 'user', 'icon', 0, '/', 'f1.jpg');
                         }
                     }
-                    // no redirect here because it is not cached
-                    $theme = theme_config::load($themename);
-                    $imagefile = $theme->resolve_image_location('u/'.$filename, 'moodle');
-                    send_file($imagefile, basename($imagefile), 60*60*24*14);
                 }
             }
+            if (!$file) {
+                // bad reference - try to prevent future retries as hard as possible!
+                if ($user = $DB->get_record('user', array('id'=>$context->instanceid), 'id, picture')) {
+                    if ($user->picture > 0) {
+                        $DB->set_field('user', 'picture', 0, array('id'=>$user->id));
+                    }
+                }
+                // no redirect here because it is not cached
+                $theme = theme_config::load($themename);
+                $imagefile = $theme->resolve_image_location('u/'.$filename, 'moodle');
+                send_file($imagefile, basename($imagefile), 60*60*24*14);
+            }
 
             send_stored_file($file, 60*60*24*365, 0, false, array('preview' => $preview)); // enable long caching, there are many images on each page
 
diff --git a/lib/gdlib.php b/lib/gdlib.php
index 68d891aac81..65e6d5ebd7b 100644
--- a/lib/gdlib.php
+++ b/lib/gdlib.php
@@ -166,19 +166,27 @@ function process_new_icon($context, $component, $filearea, $itemid, $originalfil
     if (function_exists('imagecreatetruecolor') and $CFG->gdversion >= 2) {
         $im1 = imagecreatetruecolor(100, 100);
         $im2 = imagecreatetruecolor(35, 35);
+        $im3 = imagecreatetruecolor(512, 512);
         if ($image->type == IMAGETYPE_PNG and $imagefnc === 'imagepng') {
             imagealphablending($im1, false);
             $color = imagecolorallocatealpha($im1, 0, 0,  0, 127);
             imagefill($im1, 0, 0,  $color);
             imagesavealpha($im1, true);
+
             imagealphablending($im2, false);
             $color = imagecolorallocatealpha($im2, 0, 0,  0, 127);
             imagefill($im2, 0, 0,  $color);
             imagesavealpha($im2, true);
+
+            imagealphablending($im3, false);
+            $color = imagecolorallocatealpha($im3, 0, 0,  0, 127);
+            imagefill($im3, 0, 0,  $color);
+            imagesavealpha($im3, true);
         }
     } else {
         $im1 = imagecreate(100, 100);
         $im2 = imagecreate(35, 35);
+        $im3 = imagecreate(512, 512);
     }
 
     $cx = $image->width / 2;
@@ -192,6 +200,7 @@ function process_new_icon($context, $component, $filearea, $itemid, $originalfil
 
     imagecopybicubic($im1, $im, 0, 0, $cx - $half, $cy - $half, 100, 100, $half * 2, $half * 2);
     imagecopybicubic($im2, $im, 0, 0, $cx - $half, $cy - $half, 35, 35, $half * 2, $half * 2);
+    imagecopybicubic($im3, $im, 0, 0, $cx - $half, $cy - $half, 512, 512, $half * 2, $half * 2);
 
     $fs = get_file_storage();
 
@@ -220,6 +229,17 @@ function process_new_icon($context, $component, $filearea, $itemid, $originalfil
     $icon['filename'] = 'f2'.$imageext;
     $fs->create_file_from_string($icon, $data);
 
+    ob_start();
+    if (!$imagefnc($im3, NULL, $quality, $filters)) {
+        ob_end_clean();
+        $fs->delete_area_files($context->id, $component, $filearea, $itemid);
+        return false;
+    }
+    $data = ob_get_clean();
+    imagedestroy($im3);
+    $icon['filename'] = 'f3'.$imageext;
+    $fs->create_file_from_string($icon, $data);
+
     return $file1->get_id();
 }
 
diff --git a/lib/outputcomponents.php b/lib/outputcomponents.php
index 514eac9b055..4bd0673dc2b 100644
--- a/lib/outputcomponents.php
+++ b/lib/outputcomponents.php
@@ -321,6 +321,9 @@ class user_picture implements renderable {
         } else if ($this->size === true or $this->size == 1) {
             $filename = 'f1';
             $size = 100;
+        } else if ($this->size > 100) {
+            $filename = 'f3';
+            $size = (int)$this->size;
         } else if ($this->size >= 50) {
             $filename = 'f1';
             $size = (int)$this->size;
diff --git a/pix/u/f3.png b/pix/u/f3.png
new file mode 100644
index 00000000000..27e35162046
Binary files /dev/null and b/pix/u/f3.png differ
diff --git a/theme/upgrade.txt b/theme/upgrade.txt
index 4e9b5f1a37a..4d18a33411a 100644
--- a/theme/upgrade.txt
+++ b/theme/upgrade.txt
@@ -2,6 +2,11 @@ This files describes API changes in /theme/* themes,
 information provided here is intended especially for theme designer.
 
 
+=== 2.3 ===
+
+optional changes:
+* add new u/f3.png image when theme contains customised f1 and f2 default user images
+
 === 2.2 ===
 
 required changes: