diff --git a/user_guide/libraries/image_lib.html b/user_guide/libraries/image_lib.html
index b6a3447..0baad8c 100644
--- a/user_guide/libraries/image_lib.html
+++ b/user_guide/libraries/image_lib.html
@@ -112,6 +112,7 @@
 <p class="important"><strong>Note:</strong> In order for the image class to be allowed to do any processing, the
 folder containing the image files must have write permissions.</p>
 
+<p class="important"><strong>Note:</strong> Image processing can require a considerable amount of server memory for some operations. If you are experiencing out of memory errors while processing images you may need to limit their maximum size, and/or adjust PHP memory limits.</p>
 
 <h2>Processing Functions</h2>