Finer Things in Tech:

In iPhoto for iOS, you can compare multiple photos at once. You can even zoom in on one or each of them while comparing.

With one photo selected, simply flick another up from the photo strip into the lightbox, which can preview a total of six. You can also long-press on them. Flick photos away from the lightbox to remove them. Tap photos in the lightbox to preview them on top of the others.

iPhoto for iOS is available in the App Store.