PhotoScan aims to assist the user, when taking pictures of documents on a level surface, by controlling the tilt of the device through the inbuilt sensors. It achieves this through a flashing green and red capture button. When the button is green and starts to flash, your device is level and you can take a picture of the document. If the device is not level, the capture button will appear red and the user will not be able to take a picture.
There are 3 tilt sensitivities that can be set through the settings menu: low, medium and high. The default tilt sensitivity is set to medium. You can also disable or enable the camera flash and the button flash through the settings menu.
Please note that when the device is held level for a while the orientation sensors will return an unknown orientation, and so it is not guaranteed that your image will appear in the correct orientation that you held the phone. However, this can easily be fixed through an editing application. This is normal with all devices.
Unfortunately, it appears almost impossible to design an application that works well on every Android device (especially camera applications!), but if you have any issues, please send me an email and I will do my best to find a solution. Thanks!