Catalogs & Sessions, Migrating to Capture One

Migrating Apple Aperture Libraries to Capture One Pro

Apple will release macOS Catalina 10.15 in October. In a knowledge base article on their website, Apple confirms that Aperture will not run on this new version of macOS. Some may choose to postpone upgrading macOS in order to continue using Aperture. I recommend migrating to Capture One Pro.

When Apple announced in 2014 that they had ceased development of Aperture, I chose to find a new raw image editor. I wanted all the Aperture features I loved, plus all the features Apple confirmed it was never going to deliver.

I used Lightroom prior to using Aperture. After Apple’s 2014 announcement, I tried it again. With user interface and performance issues, Lightroom still didn’t measure up, so I downloaded Capture One Pro’s 30-day free trial and it quickly became my image editor of choice.

After spending a few weeks importing and editing images from my Aperture archives, I was impressed with how quickly and easily I adapted to the new workflow. Even better, the image quality of Capture One is far superior to Aperture’s and the Aperture Library import tool is more complete than Lightroom’s. Capture One Pro almost immediately felt like home and is now my go-to tool for photo editing.

Migrating between Aperture and Capture One Pro may seem intimidating, but it can be done smoothly. When I first downloaded Capture One Pro, I had over 50,000 images in my Aperture Library. After some careful trial and error, I developed a workflow to easily migrate all my images to Capture One. I’m here to share that with you – if you prefer visuals, I also go through the process in this video:

Information imported into Capture One

Before you migrate your Aperture libraries into Capture One Pro’s Catalogs, you need to know what Capture One imports, and how to preserve the information Capture One does not import.

Image Files and Versions

Capture One Pro imports all the images in your Aperture Library as referenced images. If your Aperture Library is “Managed” (the images are stored inside the Aperture Library), you need to relocate the original images to a referenced location outside the Aperture Library before migrating to Capture One Pro. You do not want Capture One Pro to reference images stored inside the Aperture Library package directory. Capture One Pro also imports all the image versions as Capture One variants.

Metadata, Keywords and Attributes

The following metadata in Aperture libraries is preserved and directly imported into Capture One Pro.

  • All Aperture color labels are imported
    • Aperture Color Labels – red, orange, yellow, green, blue, purple, gray
    • Capture One Color Labels – red, orange, yellow, green, blue, pink, purple
    • Aperture purple is imported as pink, and Aperture gray is imported as purple
  • Aperture Versions are imported correctly as Capture One Variants
  • All Aperture keywords and IPTC metadata are imported to Capture One
  • All Aperture star ratings are imported to Capture One

What doesn’t get imported?

The following is a list of attributes in an Aperture Library are not imported into Capture One along with some recommended steps to preserve them.

  • Flags – Capture One does not have “flags” as an attribute on images. Filter your Aperture library for flagged images and add a special keyword to them to save the flag status.
  • Custom Metadata Fields – Capture One does not support custom metadata fields. You will need to move your custom metadata field information to standard IPTC fields in order to preserve it. As with flags, I recommend filtering on your custom metadata fields and adding special keywords to save this information.
  • Books, Slideshows, Light Tables, Web Journals, Web Pages – Capture One Pro does not have these products. If you want to preserve them, create an album in your Aperture Library for each one before migrating. Aperture albums are imported into Capture One as albums and will help you retain the list of images in each of them.
  • Image Stacks – Aperture Stacks can stack different images. Capture One Pro stacks can only stack variants (versions) of a single image. In order to preserve your Aperture stacks, create a special album for each stack in your Aperture Library before migrating it. Aperture albums are imported as Capture One albums.

Keywords deserve special attention. The Aperture keyword field does not honor keyword hierarchy even though the Aperture Keyword tool provides a keyword hierarchy. To preserve your hierarchy, export your keyword list from the Aperture keyword tool to a text file and import that text file into your Capture One Catalog using the Keyword Tool before you migrate any images to Capture One. This is illustrated in the video above.

Global and Local Adjustments

Every photo editing software package has its own algorithms when it comes to adjustments – these are usually not transferrable between programs. Capture One Pro will import many global adjustments and do a best-effort at converting them to their corresponding Capture One Adjustments. You will have to review these converted adjustments and refine all of your images after importing into Capture One.

Aperture local adjustments (brushed-in and brushed-out) are not preserved. You will have to recreate them in Capture One using Layers and Layer Masks, which are far superior to Aperture’s brushing in and brushing out. Each Layer with a Layer Mask can reflect multiple adjustments using almost all of the Capture One Pro adjustment tools. Recreating your local adjustments in Capture One Pro should take less time than it took to create them originally in Aperture.

A learning good exercise for your 30-day trial period is to bring over your Aperture archives and recreate their look in Capture One Pro. It will get you familiar with Capture One Pro’s corresponding adjustment tools and how the Capture One Pro controls work. Plus, Capture One offers free tutorials and webinars to help you master the software quickly

Preparing for the Migration

It took several attempts to develop the right workflow for migrating my Aperture libraries into Capture One. Before migrating, you need to prepare your Aperture Library and Capture One Catalog and create a working folder. Here’s a checklist to help you prepare for your migration:

  • Create a new master Capture One Catalog
  • Create a working directory for temporary Aperture ibraries and Capture One Catalogs

    • Export the keywords from your Aperture Library keyword tool to a text file in your working directory
    • Import the working directory keyword text file into the Capture One Master Catalog Keyword tool
    • NOTE – Commas are not permitted in keywords – a comma is a keyword separator character
    • Get familiar with the Aperture “Export > Project as New Library” dialog screen
      • UNCHECK “Copy originals into exported library” – they are referenced outside the library
      • UNCHECK “Copy previews into exported library” – Capture One will not import previews
      • CHECK “Show alert when finished” – handy to know when Aperture finished an export
      • Use “File > Relocate Originals” to move originals to referenced folders outside the Aperture Library

Relocating your originals to referenced folders outside the library is very important. Capture One does not copy your Aperture originals. It imports your Aperture originals by reference where they currently reside on disk. If your Aperture library is “managed” (I.e. your originals are stored inside the Aperture Library), Capture One will reference them there. If you later delete your Aperture library, you will remove the original files Capture One is referencing.Relocating your originals to referenced folders outside the Aperture Library may take some time if your libraries contain a lot of images. You will need to think through the folder structure you want before relocating them. A good starting point for your referenced folder structure is the organization you use inside your Library. You probably put a great deal of thought into that structure.

Recommended Migration Workflow

Once you have completed the preparation steps, the following migration steps will get you through the process of getting your images from Aperture to Capture One. The video linked to this article illustrates the preparation and migration processes. I recommend migrating in small batches. This will let you get comfortable with the process, allow you to edit your images in a smaller Capture One catalog before importing it into your master catalog, and help you track of your progress. I chose to migrate project by project since that is the library organizational unit that Aperture uses to “contain” images.

  • Master Aperture Library > Small Aperture Library > Small Capture One Catalog > Validate / Edit > Master Capture One Catalog
  • Select a project in your Aperture library and Export to a New Library in your working directory
  • Create a Capture One catalog in your working directory and import the new Aperture library
  • File > Import Catalog > Aperture Library
  • Validate all the images were imported and edit the images in the temporary Capture One Catalog
  • Close the temporary Capture One catalog and import it into your master Capture One Catalog
  • File > Import Catalog > Capture One Catalog

Validate the set of images imported into the master Capture One CatalogCapture One will import all the images and adjustments from the temporary Catalog and recreate previews and thumbnails of the imported images in the master Catalog. Let this process complete.

Repeat this process until all of your Aperture Library images have been successfully migrated into your master Capture One Catalog. If you have multiple Aperture Libraries, use multiple corresponding Capture One Catalogs in order to keep things straight. Do not hurry this process. Be patient and take your time. It is a deliberate and methodical process designed to ensure 100% success.

Comparing Aperture Organization to Capture One User Collections

The Library Tab in Capture One is where you organize your image collections. There is a Folders section that shows you where all of your images reside on disk. There also is a User Collections section that allows you to create virtual organizations of your images that may differ from the disk folder structure.

When you import an Aperture Library into a Capture One Catalog, some User Collections are created automatically. When you import a Capture One Catalog into another Capture One Catalog, you automatically get a User Collection that includes all the user collections of the imported Catalog.

Here are the similarities and differences between Aperture Library organization and Capture One Catalog User Collections.


  • Aperture Projects are converted to Capture One Projects
  • Aperture Folders are converted to Capture One Groups (Folders)
  • Aperture Albums are converted to Capture One Albums
  • Aperture nested Folders become Capture One nested Groups
  • Selecting a Project displays all the images in all the Albums it contains
  • Changing Inspector / Tool Tab panels does NOT change browser/viewer panel
  • Capture One has many built-in filters that let you search you catalog
  • Capture One creates a User Collection Group named after the imported Aperture Library
  • Your Aperture Library organization structure is recreated inside this Capture One Group
  • Aperture and Capture One allow you to place your tools on the left or right side
  • Aperture and Capture One allow you to customize the user interface (Capture One even more)
  • Customizable user interface (in Capture One can define and switch between workspaces)
  • Full screen, dual-monitor and floating resizable tool palettes support


  • Projects are how Aperture groups images. Albums are how Capture One groups images.
  • Capture One creates an Album in each imported Project that holds the Aperture Project images.
  • Aperture associates images with Projects. Capture One associates images with Albums.
  • Aperture Versions can reside in different Albums. Capture One variants cannot (except Smart Albums).
  • Aperture Stacks can have different images. Capture One stacks contain the variants of a single image.
  • Selecting a Folder in Aperture displays all the images it contains.
  • Selecting a Group in Capture One does not.

If you don’t already have Capture One, download a 30 day trial and try it out.

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Walter Rowe
Walter Rowe

Walter Rowe a professional photographer specializing in portraits for couples, families, children, high school seniors, and working professionals. He also photograph engagements, family events, and headshots for professional profiles. He has also worked with restaurant owners to show their space, the owners and staff, and the incredible food they serve. For each client he strives to create an emotional connection between the viewer and the subject, and to present the subject in the most flattering manner.

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Comments (53)

Chris Rusbridge

Another difference I discovered at some cost: Aperture can handle images in grayscale (8 bits or 16 bits per pixel) as well as RGB; Capture One Pro can only handle images in RGB. So you have to convert any grayscale images to RGB. This can be done after making your Aperture images referenced, using a batch conversion tool xnconvert (there may be others). But it’s still a right pain!

Francis Mariani

How do you determine which images are grayscale?

You have to use a photo editor to inspect the color profile assigned to the image. If the image is identified as grayscale, you need to convert it to RGB.

Chris – Thank you for your excellent tip regarding grayscale images. This also was discussed recently in a Facebook group where Capture One users congregate. I suggest requesting that support for grayscale images be added to Capture One by opening a support case.

I have a managed Aperture library of ~30,000 images.
1. Do you recommend creating the “outside of Aperture” referenced folder structure while in Capture One–ie create the empty folders on my hard drive in the folder section in the C1 Library Tab.
2. Once the “Outside” folder structure structure is created, do you recommend “relocating originals” project by project?
3. If so, will the exported project folder still be called an Aperture Library and follow the same steps set out in the video to bring the images into Capture One?
4. I have tried to attach a screenshot of a section of my Aperture Library Tab illustrating my folder structure. [I cannot tell if it attached.] Would the “outside” folder structure need to have both the blue outlined level of folders and the red outlined level of folder, or just the blue? If you recommend relocating “project by project”, can I do that by exporting the red level of project, eg into a blue outside folder (eg. 20010 Nepal & Hong Kong Aperture folder into ASIA outside Aperture folder? Most of the Trip folders in my library has 2000-3000 images (all but one are JPEGs)

In case the screenshot did not make it. The “Blue” level folders, which are immediately under the word PROJECTS, are Places, eg Africa 2006, Africa 2013, ANTARCTICA 2005-6, ASIA, CENTRAL & SOUTH AMERICA, EUROPE, etc. The “Red” level folders are individual trips, eg 2010 Nepal & Hong Kong with a subfolder for a slideshow, usu with Part 1 & Part 2 subfolders, A filebox folder for Hong Kong, a folder for Nepal with subfolder fileboxes for places within Nepal–eg Katmandu, Trekking, Rafting, etc. In the China Red folder, the subdivision has City folders with subfolder fileboxes for places within the cities visited [my most complex trip file structure].

I realize this is very granular and may be more than you signed up for. Any help you can give on this would be greatly appreciated!

Many thanks,

Gale – I do not recommend creating the referenced folder structure inside Capture One prior to the migration process. When you import your Aperture library into Capture One, Capture One will add the referenced folders to the catalog automatically.

How you relocate your originals depends on the organizational structure of your Library. You certainly could go project by project, especially if that helps you better keep track of progress. Relocating originals to referenced locations outside the Aperture Library does not create new libraries. It only changes the location on disk where the images in the library reside. Once you complete the relocation process, follow the instructions in the article. Relocating the originals is one of the recommended preparation steps prior to migrating to Capture One.

The referenced folder structure outside the Library does not have to match the organization inside your Library. I assume you have likely spent some time thinking about and developing the organization inside your Library so it would make sense to use the same folder structure outside the Library to store your referenced images.

I am unable to view your attached screenshot. Based on your description it appears your Projects are several levels deep inside folders in your Library. Remember that images are “owned” by Projects (the Filebox icon) in an Aperture Library. Albums and Folders inside a Project are merely virtual organization tools to help you better sort and maintain the pictures inside the Project. Folders “outside” these Projects allow you to group and organize your Projects.

View the Apple Aperture User Guide online for a refresher in Library organization.

The physical disk folders you relocate your images into will hold exactly the images you relocate into them. You will want to learn to work with User Collections in a Capture One catalog in order to mimic the same structure and behavior you are familiar with in Aperture. See my notes on the similarities and differences between Aperture and Capture One at the end of the article.

Dirk Dittert

Thank you for article, Walter. I have been working on a similar migration over the last twelve months with an Aperture library that contained about 85.000 images taken over the last decade. Aperture has always been great because it offered great flexibility and speed for all your image organisation needs. I’m also very much enjoying Capture One which offers great image quality and image editing features that are far superior to Aperture. It really is sad that Apple stopped developing Aperture!

I’d like to share a few tips and tricks that I found during my migration that were not mentioned in your article. Most of the migration was done with Capture One 10 but I don’t think that there have been any major changes to the import process since then. Here we go:

Aperture had better support for videos than Capture One does. Most iPhone users will probably have a few videos in their Aperture library. It is important to know that Capture One does not deal with files ending in .m4v and will not migrate them properly. There is an easy fix, though: rename your files with the extension .mov. Capture One imports and plays those files without problems and all other software doesn’t care about the new file extension. This is a bit annoying, as .m4v is the default extension for everyone with iPhone videos on the Mac.

Smart Albums were much more flexible in Aperture than they are in Capture One. It was possible to have smart albums that could reference any image of your library, no matter where it was located. You need to assign a keyword to those images before the migration if you were using those capabilities to be able to track which image belonged to which smart album. Nevertheless, you’ll also have to reorganise those albums to fit within the capabilities of Capture One. But that’s easier to do after migration based on that keyword. See my comments about sizing for this topic as well.

Deleted and rejected images require some special handling as well. The Trash won’t be migrated, so make sure those images really aren’t needed anymore. Rejected images should be tagged with the red color before migration. If you used that color for something else in Aperture before, you need to make sure to switch that meaning over to another color or keyword before you proceed with the migration.

Sizing is a very important aspect for your migration: You need to make sure to have at least ten percent of your Aperture library size as free space for the previews that Capture One generates after the import. This might be a concern if your image library is located on an SSD. Another important sizing aspect is the number of images in your library. Aperture had no problem handling at least 100k images in a library (probably unlimited from the speed I have seen over the years). However, this is not the case with Capture One. Phase One did a great job pushing the limits on catalog size but I found 30k images to be the maximum that can be handled with ease on a current MacBook Pro. The more images you have, the longer the initial catalog loading time will be and the more you will regret to accidentally click on „All Images“ in Capture One. If if your library is larger, I recommend splitting it into smaller catalogs (e.g. by year). It is a pain to keep those catalogs but it is far preferable to dealing with a slow application.

Image Cropping will not always be transferred correctly to Capture One. In some cases it will result in a 1×1 crop after the migration. It’s a simple thing to browse your images and look out for suspiciously dark previews in Capture One.

You already mentioned that stacks work differently in Capture One. This really is an area to further improve Capture One! I used those quite extensively to group parts of panorama images, HDR images, focus stacks, and so on. It is not practical to migrate those to albums at all. A workaround is to use colours for your stacks to at least keep them visible within the image browser of Capture One. It is clunky but will work for the time being. Of course, you need to perform this step before your migration to Capture One.

Please do not underestimate the time you need to put into your images and your catalogs after migration. Even though the importer does a lot of the heavy lifting, you will need to spend a significant amount of time on your catalog structure, keywords, workflow and your images after the migration to make them feel native to Capture One. Many edits of your images are lost in the process and need to be recreated in Capture One. It’s better to get started immediately because sooner or later there will be something that requires you to update to OS X 10.15. That clock will start ticking with the release of 10.15 in October! But with your guide and these tips and tricks, I’m sure you’ll get ahead of it!

Success loves preparation. The more cases you plan for before your migration, the easier it will be to deal with the fallout afterwards. There are quite a few kinks to work out but I have to say that Phase One did a good job with the Aperture import! The Aperture import of Lightroom Classic is a bad joke that can easily destroy your Aperture image library in the process and doesn’t really produce any results worth taking that risk for. Short: Capture One is definitely the (only?) way to go for long-term Aperture users!

Dirk – I appreciate your detailed response. You raise many excellent points that I encourage people read.

Smart Albums are very similar in Aperture and Capture One. Smart Albums outside a project search the entire catalog. Smart Albums inside a project only search within that project. If you can search for it in Capture One, you can create a Smart Album for the same criteria using a button on the Search pop-up dialog.

Yes, it does take longer to load catalogs as they grow. My experience with Adobe Lightroom was even worse. My current Capture One catalog is over 60,000 images and I have no issues opening it on a 2012 MacBook Pro. Plenty of memory and placing the catalog on an internal SSD improve performance dramatically. I have 16GB of RAM. Fortunately the latest models from Apple allow up to 64GB of RAM. Buy as much as you can afford. More is better.

The amount of disk space required for the Capture One catalog will vary depending on the size of previews you configure in Capture One preferences. Aperture and Lightroom are similar to Capture One in this regard. The larger the preview, the more space required since previews are stored inside the catalog folder.

Success loves preparation. Well said!

Mr. Robbi Luscombe-Newman

Some great info here..with the arrival of OSX Catalina I am faced with trialling Capture, ON1 and Lightroom re migrating my Aperture libraries. I broke my Aperture libraries into epochs or client types so will have to deal with each one.
Unfortunately I chose to absorb my RAW files into Aperture rather than reference them. So that will be my biggest drama.
So sad Apple ditched Aperture. They should have on sold it.
I found it outstanding despite having to export ‘best’ selection images to PShop for final adjustments. Aperture – PShop – Preview was the normal workflow. For most social media/web/ and small press client.
Anyhow I will keep one machine alive on Mojave to access Aperture in the meantime as I migrate. Still trialling Capture, ON1 but not going to Lightroom as it never ‘spoke’ to me.

I did trial Capture before but that was back when it was split software.

Agreed there is a lot of good information here. I have been hanging on with Aperture on Mohave but I know it is time to move. I have narrowed my choices down to ON1 and Capture One too. I would like to know which one you chose, Robbi, and why.

Chris Rusbridge

Walter, I did raise a bug report with C1Pro but they simply replied that they didn’t support greyscale images as the software was designed for colour, or some such. However, I have (I hope) managed to convert all my greyscale images to RGB, and I’ve also worked out settings on my scanning software so that future black and white images will be in RGB. (Mind you, the drivers for my scanner are 32-bit, so won’t run in Catalina, but that’s another story.)

I also decided to buy ApertureExporter, as I figured it’s best to have one set of images on a disk somewhere that has all the Aperture adjustments baked in, by Aperture. Since I understand that Capture One Pro does not handle brushed adjustments like dust spotting, and some of my old retrocoverted Kodachrome slides have hundreds of dust spots removed. I may need to find a way of using the AE-exported files rather than the imported ones from Aperture.

ApertureExporter is a bit clunky. You can run the demo without paying anything and it will export up to 10 images per project. That run took 11 hours for my 1,000 plus projects. After I’d paid to register the project, I started the full transfer. I suspended it after 11 hours, probably 2/3 done, and restarted this morning with its “resume mode”. This was a bad idea! At 5 pm it has still not finished checking all the albums and projects to work out where to start exporting again! So, if you use this software, please don’t stop it with the aim of restarting!

Chris – ApertureExporter is a well-known tool among Aperture users who are migrating to other tools. Glad you found that. You also provide a fascinating tip regarding “pausing” and “resuming” and how long it takes to figure out where it left off. I imagine it is crawling your entire Library, image by image, looking for corresponding exported version, until it doesn’t find any more. Perhaps this insures that it doesn’t miss anything should your Library have changed since it previously ran. Having those baked RGB files will be helpful also for comparing your results in Capture One to what you previously created in Apple Aperture. You can always remove the baked RGB file later for images that you feel you have edited in Capture One and achieved the look you had in Apple Aperture and thus no longer need the RGB file.

If you want to start from scratch and don’t care about the details can you just relocate the originals and import the images?

Hi Stephen. Yes, you can relocate originals outside your aperture library and import them into Capture One as though you were importing new pictures from your camera. If you do this, I encourage you to create a metadata preset with your contact information and apply that preset during import. It will save you time and insure all your pictures have contact info metadata.

Bill Benson

Great video–Thanks! Two questions:
1. Your video assumes that Aperture albums are contained within Aperture projects. In my case, my albums are separated because the albums contain selected images from different projects, even different years. How can I deal with that issue.

2. After I import temporary C1 catalogs from the working directory into Photomasters, can I safely delete the temporary C1 catalogs and the temporary Aperture libraries that had been imported to those temporary catalogs? The actual photos are on external drives as referenced images, while my working directory is on my desktop.

Mac Pro, 10.14.6, C1 Pro 20

1) Because Albums are merely virtual collections (lists), and they work the same way in Capture One as they do in Aperture, your albums that appear outside of any project will migrate over perfectly in tact with no worries about losing information.

2) After you import your intermediate (temporary) catalogs into your master catalog, and you have validated the information in the master catalog, you can safely delete the intermediate catalogs.

You may choose to save all your intermediate catalogs until your entire migration is complete. Each time you import one of these intermediate catalogs into your master catalog, the master catalog will create a new album in the Recent Imports folder (right below “All Images” in the Library tool) just for that catalog import. If you find something did not import correctly, you can select that specific Recent Import album, delete all those images from the master catalog, and re-import the intermediate catalog you saved.

McKay Savage

Thanks Walter for this detailed process. I’m starting the migration now. One area I’d appreciate if you could comment more on is the pre-migration process around Albums. Since Aperture allows photos to be in multiple albums, what was your process for not having a lot of duplicate images when moving albums to Capture One?

I don’t use a ton of albums, but the ones I do have are all cherry-picked photo sets pulled from one or more projects (for example, good profile pictures of myself or final selection albums for a client). I really don’t want to have more than 1 master variant per photo on my hard-drive if possible. Any advice?

Albums are merely virtual collections (lists) in Aperture just as in Capture One. In Aperture, actual disk files are associated with Projects. An image can be in as many albums as you like in Aperture. All of these albums will reference the same image file. Capture One works exactly the same way. When you import your Aperture Library into Capture One, all of the albums will be migrated perfectly and all album references for a given image will refer to the same physical image file on disk. There will not be any duplication of actual image files.

Lorne Stobbs

I have approximately 1200 photos in Aperture of assorted Fungi in different project files. Each photo has metadata attached (Version name, keywords, caption, copyright notice, date, pixel size, file size, principle path, location). I am using High Sierra on a MacBook Pro. If I migrate these files over to Capture One, will any of the metadata described above be carried over with the photos pr will this all have to be set up in Capture One and manually re-entered for each photo?

Capture One is very thorough in migrating metadata from Aperture. All of the metadata in Aperture is moved to Capture One. The only exception is custom metadata fields that Aperture lets you create. Capture One has no place for that information and will not migrate it.

Hi Walter, thank you for your excellent guide which I found only too late… After much trial and error and finally inspired by your workflow I found a quite easy way to import an Aperture library to Capture One even without moving the masters to referenced folders (which I hadn´t, not knowing how important this is).
In the meantime my old Mac was way to slow to repeat the whole correct procedure again. So the originals were inside the Aperture libraries. I had exported the Aperture projects as separate libraries to keep their size managable. Importing the libraries into Capture One worked well until I moved the masters out of the libraries to their new location. The – now – referenced masters were gone and I did not know how to reference them back to the new catalog. I knew how to do that with single photos (in German “Bild / Finden”, then browse and find the original in a folder, click on it to reference it again), but this could not be a solution for my over 70.000 photos…

So here is the solution.

– Open a new CO Catalog as a “Transfer” catalog.
– Import an Aperture library into this catalog.
– Check if everything is imported.
– Export the new CO project as a catalog. Important: check the box “include referenced originals” (don´t know the exact english text as I work in german)!
– Import the new CO catalog (the former project) into your main CO catalog.
– Check if everything is there, including the originals.
– Delete: 1) the pictures in the transfer catalog, 2) the Aperture library, 3) the freshly imported CO catalog (the former project)
– Check again in the main catalog if the originals are still there
– Only then empty your bin.

This is a simple way to go and works fine.

I hope this can help other people as well.


Yes, creating an intermediate catalog, and exporting it to a second intermediate catalog with the checkbox “include referenced originals” is a good work around. Thanks for sharing that!


Great article, Thank you! I have 10 years of Aperture managed libraries. I am new to Capture One and learning the hard way that Referenced libraries are the way to go. Unfortunately I updated my MAC to Captiva, so i can no longer open Aperture to do the pre-work suggested above. I am looking for a workflow to get my Aperture libraries to CO with the end result being CO catalog with references to photos on a drive rather than the Aperture libraries – so I can then remove all Aperture libraries. Can you help me to understand the best workflow variations for someone who like me who already made the move to Catalina and is brand new to CO? Thank you again for the great article!

Hi Michele. There is still a way to migrate to Capture One. The saving grace in this situation is that Capture One preserves all of your organization within your libraries. When Capture One imports your library, it creates a User Collection for each library. Under that User Collection, it recreates your entire Aperture Library structure – projects, albums, folders, etc. After you import a library into a catalog, you can use the User Collections structure to create a corresponding folder tree. Then you can use the Folders tool to move the images from inside Capture One.

If you have more than one Aperture Library, you can choose to import each into its own Capture One catalog, or import all of them into a single master catalog. The instructions below assume you create a Capture One catalog for each Aperture Library. I recommend this method for the sake of minimizing risk.

Step Zero is to make a fresh backup copy of all Aperture Libraries to a separate disk for safe keeping. If something goes wrong with a given library-to-catalog process, you can always copy the backup onto your computer, delete the bad catalog, and start over. Importing each Aperture Library into its own Capture One catalog affords you the safety of failing and starting over until you feel comfortable. Take your time. Plan this out. Try it. If it fails, start over.

The instructions below will move the images outside the library. The Aperture Library will NOT be updated to know their location. This is a one-time, one-way migration (thus the need for those safe backups).

1. Create a new Capture One catalog.
2. Import an Aperture Library into the catalog.
3. Examine the User Collections – it should represent your Aperture Library structure.
4. Examine the Folder tree – it will point to funny named folders in your Aperture Library.
5. In the Folder tool, click “+” to add folders that mimic your Aperture Library.
6. In the pop-up dialog, navigate to where you want the new folder.
7. Click the “New Folder” button at bottom left of the pop-up if the desired folder does not exist.
8. Select an album of images from the User Collections in your catalog.
9. Select all the thumbnails in the album
10. Drag-n-drop the thumbnails onto the corresponding folder in Folders tool.

Repeat steps 5 thru 10 until you have moved all the images for each lowest level User Collection. These steps physically move the images on disk to the referenced folder location outside the Aperture Library.

NOTE: I want to repeat this. Make a backup of all Aperture Libraries before you start. The Aperture Library will NOT be updated and will no longer know the location of the images. Capture One will not import the Aperture Library if it cannot see the images in the location specified in the Aperture Library.

Wanted you to know this was extremely helpful and I am gaining access to thousands of photos I would have lost. Now that I have completed the process and have all the photos that were managed within the Aperture library successfully moved onto hard drive and in a folder structure in CaptureOne is there any reason to keep the User Collections that were imported when I first imported the Aperture library? My hunch is no and just go with the folder structure which I created (which mimicked the collection structure). If I want I can create User Collections – but if I were to recreate the same user collections using the folders I just created it would appear duplicative (the photos wouldn’t be duplicated – but I don’t gain anything from an organization perspective). Hopefully that makes sense. Again, thanks for your guidance.

Walter, My apologies for being so informal and not using your proper name.

Hi Michele,

It is entirely up to you. If you had collections in Aperture that organized your images differently from your disk folder structure, those also should exist now in Capture One. If you delete the top level user collections in Capture One, you will lose those “other” collections you had in Aperture. If you didn’t have any, then you could delete the Capture One user collections that the import process created and just work from the folders. I find the user collections provide one benefit. If you create a Project with albums inside, then selecting the Project shows you all the images in all the albums inside that Project. You cannot select multiple folders in the Capture One folders tool like you can Projects in Aperture. Selecting a Folder in Capture One only shows the images in that single folder. It does not show you the images in any subfolders of the selected folder.


Gordon Smith

Walter, thanks too for the article.
I switched cold turkey to C1pro last year and shot all of my 2019 events as individual sessions. I have a massive archive of Aperture Libraries going back to 2004 and decided to test out the Catalog function by importing a single library. The import process went smoothly and the imported Aperture library looks good.

However, the major problem is that while the correct number of images from each Aperture Album appears in the corresponding Capture One Album, the images that are displayed are not correct. For example, an album with 1578 images only shows 16 in the viewer.

After a bit of experimenting, it appears that the Catalog just imported the jpgs from the jpg+raw pairs. When I filter out raws, I get the right number of images; when I filter out jpgs, I get very few images.

Not sure why this is. When importing an Aperture library into a catalog, Is there a way to force C1 to import both the jpg and raw files?


This is a scenario I have not tested personally. I recommend you open a support case for this. I recommend making a screen recording. Narrate what you expect vs what you actually see. Show the corresponding Aperture Library in Apple Aperture. Perhaps support can better explain what you are seeing. If I can resurrect one of my older supported cameras and take a few RAW+JPG, then I can test this myself and see if I experience the same behavior.


I took four pictures with a D800 with RAW+JPG enabled. I imported them into an Aperture Library, and selected auto-stack for RAW+JPG during import. When all stacks had RAW as the Original, Capture One imported only the RAW files. When all stacks had JPG as the Original, Capture One imported only the JPG files. When I set JPG as the Original for some stacks and RAW as the Original for other stacks, only the “Original” format was imported into Capture One for each stack. This tells me that Capture One only imports the format marked as the “Original” for stacked RAW+JPGs

Aa an additional exercise, I created an empty Capture One catalog. In the Aperture Library, I set all the stacks to use RAW as the Original. I imported the Library into the Capture One catalog. All the RAW files were imported. I then set all the stacks in the Aperture Library to use JPG as the Original. I re-imported the Library into the same Capture One Catalog that had the RAW files, and it then imported the matching JPG files. With this sequence of steps I was able to get all of the RAW+JPG files from the Aperture Library into the Capture One Catalog. This is not ideal, but it does work. I took lots of screenshots along the way for future reference.

DISCLAIMER: I do not work for Capture One and my comments should not be taken as an endorsement by Capture One for their content.

I made this video that demonstrates the process. When you click the link you will go to the YouTube page to watch it. Read the video description below the video. There I provide my recommendation for how to address this.

Gordon Smith


Thanks for the quick reply and extensive testing.

I was half suspecting that the “set as Original” was the issue, because almost all images in the Library I imported were set to JPG as Original. For background: In Aperture, I would shoot my events in Raw+jpg. Then I would batch rename and upload the jpgs directly to on-line galleries. (some events are large, with over 70K images, so converting RAW to jpg on export would be too slow).

In the second step, I would switch to RAW for any image that was ordered, but leave the rest in JPG original until one of those was ordered. Because the vast majority of images in this library were still set to JPG original, that accounts for what I saw (and what you confirmed in your testing).

Capture’s rename function is so painfully slow that I can no longer use my usual workflow of renaming and then uploading the JPGs; I just export the RAW files and rename on export. So I don’t shoot pairs anymore when using Capture. But now I know what I need to do to my old Libraries before I import them to Capture.

Thanks again for your help!

I have a few major reasons I have held onto Aperture as long as I have but now am feeling pressure to upgrade macOS and have a photo library organizational solution that is actively supported. The major Aperture features are all related in my existing workflow (space, active file structure tinkering hassle, backup), and I would love to hear, how can Capture One Pro (C1P) can bridge the gaps?

• Referenced Masters/Drive Space: Despite limited functionality, my biggest complaint with the old iPhoto was how it sucked up space by making new files for even minor edits, which made for an untenable library size and prompted my initial switch to Aperture. Now, I keep photo thumbnails on my MacBook Pro for search and organizational management while offloading the large, original files to an external drive (library is a few hundred GB, so while it may literally fit onto my SSD, it practically doesn’t with my other files). All I personally have to deal with keeping track of are the Masters, while the Aperture library file contains all the details for adjustments of new Versions, keywords, and Albums.

• Flexible File Structure: Related to the Referenced Masters point above, I appreciate that Aperture has allowed me to Move Originals from a Managed library to a referenced one, while automatically generating a consistent file structure and naming scheme. For example, I use folders by year and month with image files labeled “year-month-day_original image name from camera.” So, my current file structure is by date, but my titled Projects are all virtual (visible in Aperture but not in the file structure in Finder). However, I could easily change that with relative ease by asking Aperture to Relocate Originals (minus the hours of re-consolidating the referenced masters into a new external drive location). I worry if C1P loses support someday about being “locked in” or just having a messy file structure to manually arrange.

• Backup: I typically keep photos from the most recent few months as Managed for easy access and save my older referenced masters to an external drive that I can then duplicate to other drives for redundancy (I use a combination of TimeMachine, BackBlaze, and CarbonCopyCloner). Additionally, the Vault functionality has given peace of mind I have a comprehensive library structure backup (project organization, keywords, other ITPC metadata) in event of any catastrophic data loss. Backup is a critical piece

• Would Be Nice:
• Photo Stream/Automatic iPhone Add: With my iPhone 11 Pro, Aperture still can import through Photo Stream for all still shots, which is a boon.
• Live Photos: Aperture does not support Live Photos (no major loss, but might be nice to have), and the videos no longer appear with my newer generation iPhone.
• Video Files: I understand videos may need to have their extensions changed, or I might have to build a workflow around a separate video app (I have Final Cut Pro X but have found it difficult to establish a simple workflow since I almost exclusively just take casual phone videos).
• Sync: I dislike the subscription model and how Lightroom in Creative Cloud does not allow separation of libraries for work and personal but am extremely interested in a model that would let me operate from multiple devices in different locations while sharing the same large library. I don’t think this is an option.

I recommend opening a case with Capture One and submitting these as feature requests.

Thanks for your response! I know I raised a lot of points and don’t have a deep understanding of how the software works now to really know which of these features are current supported or could be requested. Any comments on Capture One’s capabilities to minimize storage use on a laptop and have control over backing up files?

I recommend going to the community forums and starting a discussion there.

I am another long time Aperture user who is about to migrate to C1. But there is one big nuisance in this process which seems to get little attention. On import C1 tells you:

The following properties will be imported … Crop OR Straighten …

This is an exclusive OR! I have thousands of art work reproduction that are slightly rotated and cropped. On import to C1 only the rotation is carried over, not the cropping, and this is a pita. Why is that? At least C1 could offer the option to first rotate and then crop, instead of not cropping at all.

Any suggestions?

Dmitri Liventsov

Hi every one, can I upload Aperture library with out getting access to actual software but just moving the folders into Capture One?
Thx, D

Yes, you can import Aperture Libraries into Capture One without the Aperture software.

Hi Walter, thanks for your tutorials and continued advice re moving from Aperture to CO.

In my case I have two libraries, they are now referenced, 218gb and 72gb and live on an external SSD.
The first is a digital library and the second a film library (containing some Greyscale images)
The structure I use in both libraries is a project for each roll of film or digital day/event and so have about 700 projects inside each Aperture library.

I use Aperture on an ageing iMac running High Sierra but would like to move everything across to CO running on a NEW iMac and maintain as much of the organisational set up and edits as I can.

I have done a bit of groundwork i.e. converted managed to referenced libraries and removed all video files. I think I still need to find a way to locate and convert all the Greyscale images to RGB before the migration.

I believe there is an importer tool with CO, if I understand your process correctly it does not use this importer but instead you export each project out of aperture as a new library, take it into a ‘working’ CO catalogue for tidying up and then after this move it to the main CO catalogue.

To create a new library for each project on an external drive using my old iMac and the removing and plugging it into my new iMac would take an age.. am I misunderstanding the process and what would you suggest in this situation?

Would using the importer tool on the SSD aperture library and just pulling the lot in be an option? If this is an option then what are the disadvantages of this approach over your project by project method? Secondly would this leave my aperture library unchanged and thus also available to use on aperture if I so wished.

Re images that I have edited using Aperture and SilverFX, if I export these images to the desktop and “bake in” the changes then reimport them into the aperture project, would this be a way of taking all my edits across to CO? Using film I tend to do quite a bit of dust spotting, to loose all of this on my images would be a real pain..

Thanks for reading my ramble and any advice you may have.


Hi Andy. Glad you have found this helpful.

Yes, you could import each Aperture Library all in one go. I recommend creating a separate Capture One catalog for each library and importing each library into their own catalog. If one works and the other fails you are at least half way done and do not have to start all over for both. Just delete the catalog for the library that failed, create a new catalog, and go again.

Regarding preserving your SilverFX plugin edits, yes exporting them to baked RGB files and importing them back into Aperture before the migration would be effective at preserving those edits.

Best of luck!

Thanks Walter, forgive what maybe a daft question but is it possible for AA and CO to both reference the same library on my external SSD or is this asking for trouble?


If you mean OK to reference the same image files, yes no issue since neither application changes them.

Just experimenting with CO at the moment and looking at different workflows for the swap over.
A potential problem for me are the grey scale images.
I have >3,000 film scans in grey scale and whilst CO imports them they are non editable.
CO resources point to opening the images in preview and using tools / assign profile to reassign the colour space to RGB however my new iMac does not let me choose any colour space other than “Generic Grey Profile” or “Generic Grey Gamma 2.2 profile”

I have read the comments re using terminal to create a script to batch change images but TBH i still would not know where to start with this!

Can anyone suggest other methods for batch changing the files within my referenced aperture library so that i can then export my projects in chunks of new aperture libraries for CO import as per Walters workflow above.

Thanks for any advice


This Capture One forum post has some Terminal commands you can run to convert color profile for greyscale images to RGB color space so that you can edit them in Capture One.

Walter and others:

This is very confusing. I may be making it harder than it is.

I am struggling a bit with migrating from Aperture into Capture One 20. In your video and narrative it appears you do not actually relocate the originals from Aperture to [somewhere else] even though you say this need to be done. This is done from an Aperture project, selecting the images, then File -> Export -> Originals…. Thats what I have done and have ended up with “relocated” images, about 46 gigs worth. From what I am reading and seeing that is not necessary. It sounds to me that exporting the Aperture Project into an Aperture Library–and not selecting “Copy originals…” and “Copy previews…” will bring over the originals into the exported library. Somehow. My exported libraries (sans originals and previews…or are they?) are of various sizes from a few MB to several GB. Am I correct about this? If you do not select “Copy Originals” and “Copy Previews” how will Capture one be able to locate them?

I understand what you want is referenced files but……how does CP1 know where to look for them? I do not intend on deleting my master Aperture Library.

Now that I have “relocated” 46 GB of images, do I need to “consolidate” them back into the main aperture library or can I delete them (move them to the Trash)?



It can be confusing. When you have a referenced library, and you export a project from that library into a new library, both libraries will reference the same image files on disk.

When you import that exported library into Capture One, Capture One also will reference the same image files on disk. The exported library simply gives you a small intermediate library to import into Capture One and allow you to track, project by project, where you are in the migration process.

If you have validated that your main Aperture Library has NO stored (managed) images, you can import your main Aperture Library directly into Capture One. Capture One only reads the Aperture Library so there is no risk to the Aperture Library itself.

Of most importance though is that your Aperture Library have NO managed (stored) images. All images in your Aperture Library should be in a referenced location outside the Aperture Library before importing the library to Capture One.

Walter and others:

I am struggling a bit with exporting from Aperture into Capture One 20. In your video and narrative you do not actually relocate the originals from Aperture to [somewhere else]. This is done from an Aperture project, selecting the images, then File -> Export -> Originals…. Thats what I have done and have ended up with “relocated” images, about 46 gigs worth. From what I am reading and seeing that is not necessary. It sounds to me that exporting the Aperture Project into an Aperture Library–and not selecting

I made another video with more details on relocating originals. File > Export > Originals makes a COPY of your images that are unknown to Aperture. Relocating Originals simply moves the files Aperture knows about.

Relocating Originals in Apple Aperture

What I recommend is exporting the project into a new aperture library. I recommend this AFTER you have relocated all your originals to a referenced location outside the master library. You can skip the step of creating the intermediate Aperture libraries.

Relocate all originals to a referenced location outside the library, then import the library into Capture One in one big job.

Walter: What is the reason, the purpose of keeping image files OUTSIDE of the Capture One Catalog?

The first reason I recommend this is performance. Capture One performs best with catalogs on internal SSD storage. This leads to the second reason which is space. If you store images inside the catalog, you need enough internal storage space to hold all the catalog info AND the images themselves. Storing the images in a referenced location outside the catalog allows you to separate the space needed for the catalog vs the images.

I have 1.2 terabytes of image files on external storage, and my catalog consumes over 200 gigabytes. I can manage the 200 gigabyte catalog on internal SSD storage on my iMac. I cannot manage 1.2 terabytes of images there.

Finally, it lets me easily make backup copies of my images. On my external storage device I keep more than just the images. I also keep backups of the catalog, software installers, license key files, etc. I keep multiple copies of this external disk – two at home, and one at another location that gets swapped out on a regular basis with one of the home copies.

Henrik Biørn-Lorenzen

Hi there
What about spot removal and cloning are they transfered over as well

Aperture Spot and Patch adjustments are not imported into Capture One.