iPhoto 11 ver 9.4.3, OSX 10.8.5 (Mt. Lion):
Checking the info box in Photos or Events gives the answer 10.6 GB.
Checking iPhoto Library in the Photos section of Finder gives the answer 13.72 GB.
That is a difference of 3.12 GB.
Why the difference?
iMac (21.5-inch Mid 2011), OS X Mountain Lion (10.8.5)
I think I have found the answer: the library is a very complex thing full of mysterious but apparently useful parts that serve to connect everything in various ways. The Photos/Events are just the pictures, without all the connections etc.
If I am wrong, please let me know. Otherwise I will consider the question answered. Thanks.
Yes - the iPhoto window reports the size of the photos you have - the finder reports the size of everything including all support files and versions of photos
LN
I think I have found the answer: the library is a very complex thing full of mysterious but apparently useful parts that serve to connect everything in various ways. The Photos/Events are just the pictures, without all the connections etc.
Your iPhoto library holds the original image files you imported (that is the largest part), JPEG previews of the edited photos for sharing with other applications, thumbnails for browsing the iPhoto library, small thumbnails of the faces, and database files to describe the relations between photos and other library items like albums, books, etc.
If you are syncing with iTunes there may be also an iPod photo Cache, see iTunes: Understanding the iPod Photo Cache folder
What the iPhoto Window reports is the nominal size of the resulting folder if you exported everything from iPhoto at the "Current" setting.
The iPhoto Library in the Finder contains your original photos, thumbnails, previews, cache, database and metadata files. it is always larger than reported by the iPhoto Window.
How big is my iPhoto library?
