Arachne is configurable in one other way. As mentioned above, the system automatically attempts to identify the interesting parts of the image. Usually this is done once at the start of resizing, but it is also possible to do it each time the image is shrunk by a column (or row). This is called dynamic energy (energy here is another name for importance), and can be enabled by selecting it from the Options menu. Arachne has to rethink whenever you toggle this option, and note that the computation time is longer with dynamic energy enabled. On the other hand, it often gives good results, particularly for extreme resizing.