Find and clear duplicate photos in a Capture One catalog

With Capture One alone

Capture One's importer can leave out photos the catalog already holds: tick Exclude Duplicates when you import. That stops new copies arriving. For copies already in a catalog, we found no command in Capture One that lists them, which is the gap Folio Refresh fills. If your version of Capture One has one, start there.

What Folio Refresh finds

• Exact copies, similar shots and bursts. Renamed copies, edited, resized and cropped versions, and frames taken seconds apart, from the catalog's own list of photos: referenced files and, since version 1.1, photos stored inside the catalog.
• The copy you worked on is the one to keep. It reads what Capture One knows about each copy: adjustments, a second variant, a star rating, a colour tag, an album you made, keywords. A copy with any of those is suggested to keep, with the reason, such as “edited, 3 stars, tagged Green”. The albums Capture One makes for each import, under Recent Imports, don't count.
• A photo with a second variant is never offered for removal. The variant is another edit of that very file.
• Photos already tagged Red, or in Capture One's Trash, are left out. They are on their way out, so they are not compared and never counted on as the copy a group keeps. If you use Red for something else, those photos are not checked.

What it changes, and only when you approve

One thing: the duplicates you approve are given the Red colour tag, the same rows Capture One writes when you press Red. Capture One has no Rejected flag, and Red is the tag its users reach for. Then you open Capture One, filter by the Red tag and delete them there, so Capture One removes them the way it expects. Tagging frees no space by itself; the deleting stays in Capture One.

What it never does

• Delete or move a file. Folio Refresh doesn't touch your photo files in a catalog at all.
• Write while Capture One is open. Nothing is changed while Capture One is running or has the catalog open (it keeps a lock file inside the catalog while it does). Scanning only reads, so that is safe at any time.
• Change a catalog without a backup. The catalog's database is copied first, by SQLite itself, into a new catalog in a “Folio Refresh Backups” folder beside it, which Capture One can open as it is. It never overwrites an earlier backup. If the copy fails, nothing is changed.
• Tag a photo that changed since you reviewed it. Right before tagging, each duplicate must still be the same file at the same place in the catalog, not already Red or in the Trash, with one variant and no tag, and its group must still keep an unchanged copy. Anything else is skipped, with the reason.
• Write to a catalog version it hasn't been tested with. Capture One's catalog layout isn't documented and changes between versions, so tagging is refused on any but the one tested, Capture One 16.8's. Scanning can still work on others.

Changing your mind

Every tag is recorded with what it replaced, so Undo in Folio Refresh takes the Red tag off again (with Capture One closed). The dated backup beside the catalog is there as well. Once you've deleted the photos in Capture One, it's Capture One's deletion, and its usual rules apply.

Sessions, folders and other libraries

Folio Refresh reads Capture One catalogs; it doesn't open sessions. The same care applies elsewhere: in Lightroom Classic duplicates are marked Rejected, in Apple Photos they go into a review album for you to delete in Photos, and from ordinary folders they go to the Trash. See Photos, Lightroom and Capture One.

Price

Scanning and reviewing are free, and so are the first 100 photos you act on, whether moved, added to a review album or tagged in a catalog. Then $14.99 once, no subscription. macOS 15 Sequoia or later.

The technical detail, for anyone curious how a catalog is read and written safely: Cleaning duplicate photos inside Lightroom Classic and Capture One catalogs without breaking them.