--- a/PresetMaps.wiki	Wed Feb 14 19:04:36 2018 +0000
+++ b/PresetMaps.wiki	Wed Feb 14 19:12:01 2018 +0000
@@ -68,8 +68,9 @@
   * As of 0.9.19+, map.png is optional if a mask.png is provided.  If there is no map.png, the theme will be used to decorate the map.  No objects will be added to white areas.  Use black if you want objects.
 
 ==== `preview.png` ====
-Preview image of the map
-  * size: 256 × 128
+Preview image of the map. The preferred preview is created by simply downscaling your map. Please don't abuse the preview by adding things which don't actually exist in the map. Exceptions may apply for maps with unusual dimenions or other maps which are somehow special.
+
+  * Size: 256 × 128
 
 === Optional files (for advanced features and adjustments) ===
 ==== `mask.png` ====