ImBatch is a FREE batch image processing tool for Windows. ImBatch features an excellent user interface that easy to use and understand and can convert, resize, rotate and carry out other operations on lots of images in a single operation.
Batch Tasks List
What makes this tool different from other batch image processors is its Task Structure. You can combine Tasks to make a processing sequence that will give you exactly what you want. ImBatch offers many imaging functions (Tasks) like converting, resizing or applying watermark. You can change the order of tasks, add some tasks twice or more (for example, to convert images to JPEG and PNG in one go), turn off on tasks to exclude/include them from the task processing list, hide some task parameters, leaving only the necessary ones. Also you can undo/redo all changes made in Task List.