How does the library work in Photos ?

Photos is managing the photos in a Photos Library. This is package of several databases and folders with the original image files. We are not supposed to access the originals directly using the Finder. We should use the Photos.app to retrieve the Photos for us, when we want to use them.

By default the Photos.app will create a copy of the original image file inside the Photos Library, when we import items to Photos. We cannot access the items directly in the package. The "Reveal Referenced file in Finder" command will do nothing for photos, that have been copied into the Photos Library. See: Where are the photos I imported into Photos on my Mac? – Apple Support (UK)

It is possible to import item to Photos without creating a copy in the library package. This is controlled by the Photos > Preferences > Importing: Copy items into the library. When we disable this checkmark, Photos will just reference the original image files directly in the location where they are when we import the photos. For the items, that you imported with " Copy items into the library" the command "File > Show referenced file in Finder" should show you the original image file, provided you did not move it or delete it. When we do not copy the items into the Photos Library, we are responsible for protecting the originals. If you have been importing most of your Photos from Lightroom with "Copy items" disabled, most of your photos will not have been copied into your Photos Library and are referenced in the original folders where you kept them in Lightroom.

But when you try to import photos from your iPhone, the originals cannot be imported without copying them into the Photos Library. The Photos.app cannot reference them in their original location on the iPhone, so it has to import the files by copying them into the Library.

I cannot recommend to keep the original image files outside the Photos Library and are surprised that Apple Support has recommended it to you. It is very risky and a disaster waiting to happen.

The problem is, that Photos for Mac is not a professional application like Aperture or Lightroom. Photos has no elaborate tools to fix broken references. If we ever have to restore referenced files from a backup or to move the original files to a different drive, we will have a very hard time to fix the broken references. I would only use the referenced originals temporarily, when I have to migrate an older iPhoto or Aperture library to Photos, were the originals have been stored outside the library. And then the first thing I would do is to use "File > Consolidate" to copy the originals into the Photos Library to keep them safe.

Is the system version  OS X 10.11 shown below your question still valid or have you upgraded to a more recent system version? In the more recent system versions, since macOS 10.15 Catalina, we can no longer find our original image files inside the library package and identify them. Photos is renaming internally all media files with unique names and we can only identify the image files by looking at the image, not by the filename.

Photos is not LIghtroom. If you have Lightroom I would wonder why you use Photos at all, as LR is a far more capable app than Photos - as it ought to be given that you pay for it. But more importantly, LR and Photos occupy the same place in your workflow - they are both media managers with non-destructive editing. Neither is aware of the other in the workflow, they don't communicate. Using both is like using two address books - which one is the most up-to-date? Which as the latest version of whose details? It's just a recipe for confusion.

when setting up Photo I asked Apple and they told me to untick the "copy items to Photos Library" box

This is called using a referenced library. This is perfectly normal in LR. Don't do this in Photos. Photos does not have the tools to manage a referenced library. If the path to the files changes at all - a folder or file renamed, a folder moved, whatever - you can find yourself reconnecting the files one by one. This is especially risky when the library is on one drive and the files on another volume. Really. No experienced user of Photos recommends this mode of working.

If you don't want to use the Cloud then simply sign out of the iCloud Photo Library, which you can do in the System Settings under your details heading at the top.

By default, in Photos when you import images to the Library they are stored in the Library package. (This is the opposite to referenced mode, and it's called managed mode. Photos manages the files for you.) This is opaque to the user. Photos is designed in such a way that you do all your interactions with the images via this app and this app alone. Again, a bit like managing your addresses and phone numbers: you search, edit, add and so on via the Contacts app, you don't go looking for the individual entries on the HD. Same with Photos. Everything you need to do with your images you do via the App, and everything you need to do you can be done via the app. So, for the Photos users, where the files live on the HD is not really a question. They're in the Library. Back up the library.

If you've been using LR this is a bit of a leap. But that's how it is designed to work, and given the inherent instability of Photos in referenced mode, I strongly urge you to go this way or use some other app. If you're worried about disk space then library can run perfectly well from an external disk formatted Mac OS X Extended, Journaled or apfs.

The 'Show In Finder' command only works with referenced files, not with managed ones. Why do you want to see the files? Directly accessing them for some other purpose is the kind of thing that corrupts library - and you find yourself dealing with the scenario described in my first paragraph above. Want to edit them with a different app? Then, like LR, Photos has an 'edit with' command which will send the image to another editor and so on.

If you want to access or recover those originals you use the File -> Export -> Export Unmodified Original command.

When I ask Apple how the Library works they tell me to just trust the system

You don't have to trust the system. There are alternatives. And the system doesn't work for everybody - and especially if you want to run referenced library, I would simply not trust the system.

But in summary: when you import photographs to Photos in default mode, the original files are copied into the library packed. Thereafter they are accessible via the app only. Within the library package they are stored, renamed and arranged in an opaque fashion for the end user. They can be got out again (via export/sharing etc) and everything you need to do can be done via the app.

Photos is optimised for the family snapper, probably shooting with a phone, who wants as much automation possible, so s/he can easily manage, tidy up and share the images. Other usage scenarios are possible of course, but that's what it works best for. I have yet to see a usage scenario where it makes sense to use Photos if you have Lightroom.

zesarounette wrote:

...

I definitely don't want to use the referenced mode and want to have everything safely in the library. I'm not pointing the finger at Apple Support, it probably came from me not asking my questions properly ...

Is the "File > Consolidate" you mentioned the best way to go to make sure all my photos are in the library ? Is there a way to filter which photos are and are not in the library to make sure I don't forget any behind ?

You will want to use the command "File > Consolidate" for all photos, that have not been copied into the library when you imported them. Select these photos and then go to the "File" menu. Consolidating will copy them into the library.

To find the items that need to be consolidated, create a smart album like this:

File > New Smart album

Then set the rule for this smart album to "Photo > is > referenced"

You will find all referenced items in this smart album.

I hope, there are not many left and all original image files are still in the original location.

Just to agree, again, with léonie, I import my Nikon pictures from the SD to a folder on the Desktop and I back that up to an external drive. But I import those pictures to Photos so they are copied into the Photos package. The pictures are precious, and I keep lots of copies. I keep extra copies of my iPhone pictures and of Photos that are shared with me, as well.

And it's not like those pictures are locked away and forever unavailable. There have been a number of people whom we have helped to recover pictures from old corrupted Libraries-- those original pictures are in there and, if you don't mess with the package, they'll be there until you purposely delete them. Of course, they won't have familiar file names, because, after all, with multiple cameras you would have bunches of IMG_0021s floating around--so they are given new, nonsensical filenames. But all the original metadata, dates and so on, are intact.

What you do lose if your Photos library goes belly up is the edits you made to the pictures. (Actually, some edited versions will survive in previews and such.) Those edits and added metadata (and original filenames) are stored in the Photos database that references to those crazy filenames. If this worries you, you can make a smart album with edited images and periodically export the edited versions for archiving.

The other way to lose Photos pictures is to have the hard drive on which they are stored have a psychotic breakdown like happened to me with my iPhoto library. But broken drives and broken databases can happen with any program, and that's why we keep backups.

This is a very late reply to the question above but after reading Leonie's response I have to disagree strongly with it.

As someone with a large Photos library, on an external SSD, and no interest in iCloud photo management, I have a very similar setup to the one described by zesarounette above and received a lot of bad advice about how to manage my libraries. I used a Lightroom library for many years and loved it but am strongly opposed to paying Subscriptions and being locked into software. Equally, however, even without subscriptions, we should all be careful of getting locked into ecosystems we may find ourselves unable to leave later. It seems to me that while Apple's Photos app does a very good job of managing photos in a 'locked' library (i.e. one where the user can't see or access individual images with the proprietory application, it is neither in the user's best interest to be 'blinded' like this, nor is it likely to be useful in the longer term (if, for instance, you want to switch to a different app or, as I do, access the same library with other applications).

In the same way that Photos managed to 'index' all your photos in the original Lightroom multi-folder structure, the answer is to switch off the option to import into the library and simply continue to organise your new photos in named folders as you wish to and then import the contents into the Library (without actually moving anything). the best of both worlds. True, it is a little bit more involved as a process but it is entirely free and, crucially, leaves you with a folder hierarchy and access to your images outside of the Photos app.

I hope that helps.

zesarounette wrote: And I can therefore safely delete it from my iPhone or camera or external HD ?

I am guessing that you're not using iCloud Photos.

I wouldn't go around deleting pictures until I was sure I had two independent copies of each. I have my pictures in Photos Libraries, but I also have copies in Finder folders on another drive.

One way to do this is, before you delete pictures forever, use Photos File>Export>Export Originals to send copies to an separate external hard drive. Then you'll be sure. And you can use, in the export dialog, Subfolder format>moment name, if you like, to keep the pictures arranged in folders by topic.

If you want to manage the photos in folders you should use a different application, not Photos for Mac. Photos has not much support to handle a referenced Photos Library. You will have a hard time to reconnect the originals, if you ever have to move the originals to a different drive, when the drive starts to fail or you are running out of storage, or if you have to restore the originals from backup. Apple's old professional software Aperture had a much better support for such emergencies.

To protect myself against having my photos and videos locked in the Photos Library, that can only be opened by Photos, I am keeping copies of all original image files in folders a backup drive. I like to have an archive of all original files anyway, and they are also serving as an additional backup.

zesarounette said: You’ve mentioned the “edit with” command and I have just tried it (with GIMP photo editor), but how do I get the edited result back in Photos ?

I sometimes use GraphicConverter to edit pictures outside of Photos. I go to those 3 dots in the Edit screen, choose GraphicConverter, and the picture shows up in that app. I edit the picture, and then I save. (The picture's name is a crazy sequence of apparently random characters, and it's saved in an invisible place.) When I return to Photos, a small version of the image is shown with the changes. In the upper right hand corner I'm given two buttons, Cancel or Save Changes.

Click Save Changes.