If you’ve burned an entire iPhoto library to a CD or DVD (using the iPhoto burn function), you can view the library in iPhoto without importing all the photos. You can’t make changes to a photo library you’re viewing on a disc, but you can import (copy) photos and albums from it into the current iPhoto library.
To view a photo library on a CD or DVD:
Insert the CD or DVD into your computer’s disc drive.
An icon for the disc appears in the Source list.
Click the disc’s icon in the Source list to show the photo library or libraries it contains.