Your activity gets destroyed during the Camera activity operation and re-created afterwards. You should use onSaveInstanceState/onRestoreInstanceState mechanism in your activity to preserve the image URI (and any other data) upon the activity restarts.
Like this:
@Override
protected void onSaveInstanceState(Bundle outState) {
super.onSaveInstanceState(outState);
if (mImageUri != null) {
outState.putString("cameraImageUri", mImageUri.toString());
}
}
@Override
protected void onRestoreInstanceState(Bundle savedInstanceState) {
super.onRestoreInstanceState(savedInstanceState);
if (savedInstanceState.containsKey("cameraImageUri")) {
mImageUri = Uri.parse(savedInstanceState.getString("cameraImageUri"));
}
}