Apple - Discussions - merging iphoto libraries-help!!!: "I believe there is no way to merge libraries. I researched this a few months ago ,. I've thought about how one would write an AppleScript application to merge libraries . I think this is safer than attempting to directly access iPhoto's undocumented data structures. The primary problems with this are:
1. The iPhoto API is incomplete; it supports extraction but not necessarily programmatic album creation . One might be able to use Apple's 'beta' AppleScript extension for manipulating menus and other UI structures to get around this.
2. The number of people who'd pay for this application can be numbered on one hand, and that's counting me twice. If I become unemployed I might write it. Too bad there aren't legions of overseas developers expert in iPhoto and AppleScript (hardware is too costly and market is too small).
Our best bet is too continuously moan to Apple to sell us an enhanced version of iPhoto that would import and export libraries. An application that would be to iPhoto as FinalCut Pro is to iMovie. The current version of iView MediaPro doesn't do the trick for me, though I think the author could move it in that direction. I could threaten not to buy my G5 until Apple does this :-).
If you want to write an application to merge libraries, a few hints:
1. Use AppleScript to export all metadata and images from the two or more libraries that are to be merged. (eg. Create a separate merged library.) BTW, this script might be of interest to a vendor selling an iPhoto alternative, since there's a strong data lock aspect to iPhoto. Once you put your data in, it's hard to switch applications.
a. There are AppleScripts, hosted by Apple, that demonstrate that it may be possible to use the iPhoto API to extract images and related metadata (titles, comments, album info, etc).
b. The data could be stored in a tab delimited file and an image directory with unique image names. More interesting might be to store the data in a FileMaker database and then generate the iPhoto library from the database.
2. Use a second AppleScript to create the new merged library
a. This is the harder exercise. 
An alternative approach would be to use an AppleScript and possibly an external utility (GC?) to put comments and titles into the JPEG header. This works only for JPEGs and it loses other metadata, such as album definitions, album titles, album comments and album sort order.
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