Import your existing library
Some things to note if you’re migrating from iPhoto or Aperture
If you’ve already amassed a library of photos in either iPhoto or Aperture, Photos can import its contents. For most people this is a straightforward process. If you have just one library on your Mac, you only need to open Photos and click Get Started. The app will copy the contents of the existing library into a new one that’s used only by the Photos app, and the old one will remain so that you can continue to use iPhoto or Aperture. (That said, making a backup first is wise, in case you run into an unexpected problem.)
When you click Get Started, Photos might complain that permissions on your library need to be repaired before it can be imported. To fix this, make sure the old app isn’t open, hold å+ç and then open that app to display its maintenance options. Run the option that repairs permissions, then close the app and try again in Photos.
If Photos detects that there’s more than one iPhoto or Aperture library on your Mac, it will ask which you want to import. Afterwards, Photos’ File > Import option doesn’t import or merge another library (it is for importing files stored loose on a disk into the current library). Photos provides no way to merge the contents of two libraries (at least not without an iCloud trick).
Just like iPhoto and Aperture, you can create and switch between several libraries in Photos. To import a second library into Photos, close the app, hold å and reopen it to display a list of other detected libraries, along with options to browse for one that isn’t shown and to create an empty library. Choose another library to import and a new copy for use with Photos will be created alongside the original version.
Photos uses a feature of the UNIX system on which OS X is built to enable its library, and iPhoto’s, to point to the same data without storing it twice. OS X counts references to that data, and your iPhoto library can be trashed without removing the data it and Photos share.
Star ratings and flags are converted into keywords, which can be inspected by a Smart Album’s rules
If you’ve ever used the option to store photos outside of the library package (possible in both iPhoto and Aperture), those master files will remain where they are and be referenced from your old and new libraries. Referenced files have a consequence for iCloud Photo Library – they won’t be uploaded to it. Find out on page 48 about this feature and how to overcome this limitation.
You can migrate as many iPhoto and Aperture libraries as you want, and one will be designated as the System Photo Library. Only this one’s contents are kept in sync with iCloud Photo Library, and appear in the Media Browser in other apps, including Pages and iMovie.
Earlier, we mentioned a technique for merging libraries. In the dialog that appears when you open Photos with å held, the System Photo Library is denoted. Open a different one, choose Photos > Preferences > General, turn on ‘Use as System Photo Library’ and, in the iCloud tab, turn on iCloud Photo Library. The library’s contents will be merged in iCloud with whatever has previously been uploaded. This cannot be undone.
Photos will warn you if your iCloud storage is insufficient for all of your photos. If you don’t want to pay for more, or the maximum tier of 1TB isn’t enough, follow Apple’s suggestions at support.apple.com/HT204410.
iPhoto and Aperture enable you to denote the relative worth of a photo by assigning a star rating out of five, and to flag a photo as a reminder to do something with it. Photos doesn’t have such granular options. Instead, you can simply mark a photo as a favourite. However, your ratings and flags aren’t lost when moving to Photos. Apple’s solution is to convert these attributes into keywords, which you can look up from the search bar and in the criteria of a Smart Album.