Tools
Edit in Photoshop
Open any image in Photoshop, or whatever editor you prefer, straight from Atlas. Make your edits and come back.
Point it at your editor
In Settings, under Editor, browse to your editor and give it a name. The right-click menu and the info panel's Edit button then say Edit in Photoshop and open files there. Skip this and the first Edit click will ask you to pick it.
Use it
Right-click an image and choose Edit, or use the Edit button in the info panel. Atlas opens it in your editor, and because Atlas works on your real folders, whatever you save lands right back where the file already lives.