This is the Shelf Logic® Batch Resize Screen.

For the Source, you can select photos in a database or on a folder.

For the Action, you can Resize photos or create thumbnails, as we have done here.

Thumbnails are stored in a special place so no destination needs to be specified.

In the screen below, we have chosen to resize photos so you can choose the destination for the photos.

For the Action, we've selected Resize Images and selected normal (400 pixels) for the finished size.

For the Destination, you can choose to put the resized photos in the same folder as the photos (source folder), or you can choose a folder in which to place the resized photos.

We've also indicated we want to save backups of the photo images before they are resized.