[democrite]

Since tap is used for various actions, it possibly is best to use another gesture to zoom images. I had thought the long tap suggestion was a good idea then tried it again in iBooks. Since one could tap, zoom in or out, etc. when viewing an image, a double tap does seem ti be ideal to both open and close since it can then be the same gesture. And then it could directly zoom the image without needing a menu. The long tap could be used for a popup like when selecting text, for save or share. Those gestures also match Safari and possibly other app behavior thus it's more instinctive and what the new user might most likely try.