How to rename all images together in OS X Mavericks?
Automator

You can use OS X's Automator.app to quickly rename batches of images. The Actions you want are:


Get Selected Finder Items
Rename Finder Items


Using this approach you can rename files, change the case, or append/remove specific parts of the original file name.



You can create droplet like applications using Automator to make the whole process a single drag-and-drop. Alternatively you can set up a folder action to rename any image dropped into a folder.

To learn more about using Automator, see Apple's Mac Basics: Automator.