Open a picture with Photoshop or Preview based on file location
You could build a partial solution with using Hazel and Automator.

1st, create an Automator workflow that uses the "Set Application for Files" action on received files to Photoshop.

2nd, create a Hazel rule that runs that Automator script on any images dropped into a specific folder. You could skip Hazel and just create a folder action in Automator but that would fire on any file placed in that folder and that might not be what you want.

Files modified in such a way would still open in Photoshop once removed from that folder, which is why this is only a partial solution.