A free program for Android, by IVYMOBILE.

If you have photos or videos that you do not want other people to see, you can use the Gallery Lock to hide them from prying eyes. The best part is that you can choose to make it invisible for others or just to you. This app offers a very convenient way to keep your personal information safe and private.

For those of you who are afraid that someone might steal your phone, you can use the Gallery Lock to lock your device.

You can also use the built-in camera, so your the photos you take will be automatically hidden.