There are plenty of affordable third-party image-editing applications available for your Mac, but they all lack one thing: integration. None of these amazing editors offer a way to manage your photos as well as fix them or apply incredible effects. iPhoto pretty much has the monopoly on image organisation on your Mac, but there is a way to combine the best of both worlds and have it catalogue your images but edit them with a third-party application, without the need to constantly export and import. Setting a third-party editor in iPhoto really only takes a few minutes, but it can make all the difference to your workflow if you’re serious about making your photos look the best they can. You’ll obviously need a third-party editor to follow this tutorial (take a look on the Mac App Store if you’re stuck for ideas), but once you’ve acquired one, it’s as easy as a few tweaks in the Preferences menu.
Fire up iPhoto and call its Preferences window by selecting from the iPhoto tab in the OS X Menu bar. You can also use the keyboard shortcut Command+, (comma) to instantly bring up the window you need.
Click on the Advanced tab in the Preferences window and, next to Edit Photos, select your external editor from the drop-down menu. Now when you go to work on an image it’ll be edited in the app you chose.