This overlay image can sit on top of the picker and tell instructions to the user like a frame to have the head of a person inside as guidance to better pictures.
The ImagePicker functions allow you to present a panel to the user to pick a picture from the device, e.g. from the photo roll. You can specify Camera, SavedPhotosAlbum or PhotoLibrary as source with ImagePicker.SetSourceType function. For the camera, you can use ImagePicker.SetCameraDevice to specify whether you like to get front or rear camera. ImagePicker.SetCameraFlashMode defines whether flash should be enabled by default or not. Use ImagePicker.SetCameraCaptureMode to switch between taking photos or videos.
ImagePicker.SetShowsCameraControls defines wether the standard camera controls are visible. If you hide those, you can put instructions there for your own use. As you get a script triggered for a new picture, you can automatically close the panel, when a picture is taken.
Coming soon for version 8.3 of the MBS FileMaker Plugin.