> Otherwise you have a situation where img_1_01.jpg and img_01_1.jpg does not have a complete ordering. (Good) "natural sort" implementations generally have wa

> Otherwise you have a situation where img_1_01.jpg and img_01_1.jpg does not have a complete ordering. (Good) "natural sort" implementations generally have ways of handling ties like this. It's similar to the problem of case-insensitive sort over case sensitive sets.