A while ago I merged multiple different Aperture libraries into a single big one (more on why in another post). It took a long time as some libraries had close to 10,000 photographs, but I now finally have all my photos in one library, which is what I wanted.
The process was relatively easy. However, one big problem I had was that a bunch of my photographs had a green tint over them. It was like a green layer on top of the image, which made it impossible to work with. Some looked like they'd been crossed-processed or something to that effect. Really annoying.
I tried to fix it by repairing the library, then rebuilding it, then deleting the Aperture preferences file. Nothing seemed to work. So I went to Google to see if others had experienced the green tint problem and if someone had a solution.
The green tint problem seems to be fairly common and it's been discussed quite a bit. There are several threads in the Apple forums. Unfortunately, none of the suggested fixes solved the problem for me.
In my investigation, some images that had the green tint in the thumbnails looked ok in full screen, and some the other way around. The fact that they looked ok sometimes suggested it could be the preview (the jpeg Aperture creates to display the image), so I gave rebuilding all previews a go. And that solved the problem! All my photographs are back to normal.
Here's what I did step by step:
1. Select Photos in the Library section.
That shows you all the photos in your library irrespective of which projects they're on. It's just every singe photo you have.
2. Click on any photo in the viewer and Select All.
This will of course select all your photographs. Now, anything you do from the menu will affect them all.
3. Go to Photos and select Generate Previews.
To see it you need to hold the Option key and the menu item will turn from Update Previews to Generate Previews.
And wait some more. And then keep on waiting. Aperture is generating new previews for all your photographs. To see the progress click on "Processing…" at the bottom or go to Window > Show Activity to open up the Activity window. Depending on the size of your library this step could take a long time, so be warned!
I guess you could just select the ones that have the green tint and generate previews for those only, but I found it more time consuming to go through my entire library trying to select the problem ones. I just let it do its thing while I cought up with Breaking Bad, so no problem. Hope that helps those with the same issue.