Storage

Open Settings › Storage to inspect and clear the derived data cached across the catalogue. Use Reduce Previews on Previews to remove large previews while keeping the grid thumbnails. Reduced previews do not re-enter the launch render queue; the loupe can use a thumbnail until a new preview is made. Remove All also deletes the thumbnails, which Frames rebuilds during the next scan.

Frames checks for unused as-shot preview files in the background at most once per day on launch. It removes files whose content identity is no longer in the catalogue once they are at least a day old; previews for unavailable sources remain referenced and are kept.

The controls are available once a library is open. The total leads, with a bar that splits it by store against the limit, and each store has a tile with its size and a Remove button. The Previews tile counts photographs, since each normally has a thumbnail and a larger preview file; other tiles count files. The sizes are remembered, so the tab opens on the last measurement and says when it was taken; Frames measures again once that is ten minutes old, and Refresh measures at once. Removal requires confirmation and explains the rebuild cost.

Set a derived-data limit in Settings › Storage on each device (50 GB by default). The limit is stored on that device and does not sync. Choose Trim now to run cleanup immediately. Frames also checks the limit when a library opens. Downloaded RAW originals are removed first, starting with the least recently used; older cached photo data follows. Grid thumbnails are retained, so a limit below their size may not be reached. Scene analysis is managed separately.

Store	After removal
Previews	Rebuilt from the source; Grid shows placeholders meanwhile
Edited previews	Rebuilt from local originals after launch or sync, when each photograph opens in Develop, or with the activity row’s Refresh, which can fetch originals
Downloaded originals	Fetched again when an action requires them
Histograms	Measured again from original decodes
Detected masks	Recalculated when needed
Scene analysis	Rebuilt by an analysis pass

Scan progress appears in the activity queue.

The catalogue is excluded because its ratings, verdicts and recipes cannot be rebuilt from caches.

Catalogue backups. Frames backs up the catalogue once a day when a library opens, and before an update changes its format, keeping the five newest copies beside it. Catalogue backup in Settings › Storage shows when the last backup was made, or when and why the last one failed. When backups have failed on two different days with no success between them, the main window says so once and points here; it says so again only after a backup has succeeded and failed on two more days. On a Mac, Settings › Library lists the backups and restores one.

Source-specific work. Double-click a source in the sidebar for its own panel:

• Improve preview quality shows photographs below the target proxy resolution and lets you start or stop an upgrade.
• Fill capture metadata shows missing capture data and estimated download size. Starting it fetches Photos originals one at a time, reads camera, lens and exposure, then removes the temporary download. It runs until the backlog is complete or you stop it from the activity queue.

These Photos operations are absent where no Photos source exists. Folder metadata is read from local files.