Some of the pictures at Commons are huge. They take forever to load and they start loading at the top, typically not the most exciting part of a picture. It makes more sense to initially load a low resolution picture and download the higher resolution bits as and when required. This gives the average user a much more responsive experience. In this demonstration of the Djatoka software, you will find many pictures by Ansel Adams of the Japanese-American internment at Manzanar. The scaling of the pictures is done by Djatoka in combination with OpenLayers..