The Auto-Rotation option on your Android device just lets you lock the orientation either to portrait or landscape. But how about for each app individually? So, you can determine which application should be viewed in landscape mode and which in portrait.
To manage auto rotation on Android for each application separately, do as follows:
1. Download and install Rotation Manager - Control from Google Play Store(which is Free and surprisingly offers no ads)
2. After opening the app and reading the instructions, the list of available apps on your device appears.
3. What you need to do is simply specify the screen orientation type for a specific app, by tapping the corresponding rotation icon next to it.
4. For example, you can lock your Image viewer application to be viewed only in horizontal mode, and no matter what the global auto-rotation setting is the application will be opened in landscape mode.
Note that, some applications are only available in a specific orientation and for example you can force Angry Birds to run in portrait (vertical) mode.