Although I am in general happy with Aperture these days, it has been driving me crazy for the past few days. My usual process of importing images involves dragging a folder or series of images into a project while holding down Command and Option, which triggers an import into the project by reference. I then create albums and drag the newly-imported images into them.

But… if I start adding images to albums too quickly (before the thumbnail creation is done), thumbnail references can become corrupted. This has the effect of swapping an image’s thumbnail with an existing image’s thumbnail, and it is as infuriating as it sounds. Viewing the image shows the proper image, which is clearly a different image than the one shown in the thumbnail. If I then do and undo any adjustment on the image, the proper thumbnail is recreated, but the swapped image’s thumbnail changes as well! Sometimes when I start manipulating a thumbnail-corrupted image using Adjustments, both the thumbnail and the full-sized image turn black within Aperture, and no amount of additional adjustments will bring it back.

thumbnail duddn match the big image

Here’s an account of what happens. Image A and Image B have swapped thumbnails.

Image A -> Thumbnail B Image B -> Thumbnail A

If I check any adjustment in the HUD for Image A and then uncheck it, Image A’s thumbnail is rebuilt.

Image A -> Thumbnail A Image B -> Thumbnail A

If I do the same to Image B, it’s thumbnail is recreated as well — but Image A’s thumbnail reverts to Image B’s thumbnail! They appear to have linked references to a single thumbnail.

Image A -> Thumbnail B Image B -> Thumbnail B

The only way to fix the problem seems to be to delete all the offending images from the project and re-import them. This is a huge pain in the ass. There must be a way to recreate all thumbnails in a project, but I haven’t yet been able to find a way.

UPDATE I wasn’t able to find a way because I was on a boat in the middle of the Pacific. But with 2 minutes, an internet connection, and a search engine, I found these links:

1. Apple says to rebuild the entire library by holding down Command and Option while starting Aperture.
2. This tip seems more reasonable if you don’t want to rebuild the entire library, which could take hours. You can rebuild thumbnails from the offending project by opening the Library package, navigating to the offending project folder, and removing the “AP.Thumbnails” folder.