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 (12)

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!

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,

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!

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.

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 – 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.

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.