If you have some pictures on your iPhone or iPad that you don't want people seeing when they glance at your camera roll, tech blog Digital Inspiration shows off a simple way to hide them without using any external software.
If you frequently show off pictures to your friends, but don't want them seeing a one or two pictures while you're flicking through your roll, you can crop those pictures down to hide them. Simply open up the photo library, select the photo you want to hide, tap edit and then crop the image down to the smaller area. Now, when people flip through your camera roll they won't be able to glance at any embarrassing pictures. It doesn't exactly hide the photos from snoopers, but it certainly decreases the chance they'll tap on the photo.
To get the picture back, select it again, tap edit and on the iPad tap "Revert to Original". On iPhone, you can manually recrop the image to show the whole thing. Head over to Digital Inspiration for a few more ideas for hiding those pictures a little deeper, including using Dropbox, and other third party apps.
Easily Hide Photos on your iPhone without using any Apps [Digital Inspiration]