Photoshop and Automator

Why would you use Automator to do what you want to do? I'd set up an Action in Photoshop with each step you outlined and then use Photoshop's built-in batch feature (Automate -> Batch). It's super easy to set up, just record the Action on one file, save the Action, go to File -> Automate -> Batch, select the save action, select a folder then sit back and let it do it's thing.

Actions in Photoshop are just like Automater in the OS.
Just look up "recording actions" in the Photoshop help menu.
Then look up "Batch-process files" to apply your action to a whole folder of images.

Just like aricher said, you dont need automater to do this.

I once had to format 400+ mobile jpg wallpapers into png thumnails half the size. Took 5 minutes to set up and Photoshop did all the rest of the work in under 10 minutes. Doing this by hand would have taken a day plus...