If you want it to be 'secure', build camera functionality in your app. There is no way to be sure what some random camera app that comes pre-installed on a device does. They may be sending pictures to a server somewhere without you knowing.
It's not super easy to do reliably, but you can only build the basic functionality. Failing that, require a specific app which you trust for image capture, by making the intent explicit (specify package name). This will, of course, require users to install it first if it is not already there.
I have implemented the camera in the same way as you have done. It creates the image and save it in the folder that I have created. But at the same time it saves image in the gallery as well.
I have checked for this if other apps also does that or not. And found that even other apps does that and its not the issue of only HTC have tested it on various devices. Even I am thinking how does it works.
I cant really gove you an answer,but what I can give you is a way to a solution, that is you have to find the anglde that you relate to or peaks your interest. A good paper is one that people get drawn into because it reaches them ln some way.As for me WW11 to me, I think of the holocaust and the effect it had on the survivors, their families and those who stood by and did nothing until it was too late.