Or you can use a droplet for more control, to which you can add pretty much any function Photoshop will do. Before you create a Droplet, you need to record an action. Close the file, open the actions palette, make a new action, select it, press record and open your file, work on it and Photoshop records everything you do along with the parameters, then save your file and close it. Press stop recording, then select Create Droplet and use your action you recorded. Make sure you suppress opening and closing dialog boxes in the Create Droplet dialogue box. You then select the files or folder and drag it onto the Droplet icon in the Finder. I use this all the time for batch processing more complex edits other than resizing. Very very useful to understand if you work with a large number of files.