add comment
diff --git a/auto/modules b/auto/modules
index 6aa0089..9bc2e04 100644
--- a/auto/modules
+++ b/auto/modules
@@ -104,6 +104,7 @@
 #     ngx_http_charset_filter
 #     ngx_http_ssi_filter
 #         ngx_http_xslt_filter
+#         ngx_http_image_filter_filter
 #         ngx_http_sub_filter
 #         ngx_http_addition_filter
 #         ngx_http_userid_filter