How to merge the overlay image with the camera image and save in android?

Question

I have a application that takes photo shots as well as displays a imageview like a frame. What I want to do is to merge the imageview with the data in the PictureCallback, I have read multiple tutorials but I find them difficult. Is it possible to merge and save the image in the code below? Some sample will be helpful!

private Camera.PictureCallback mPicJpgListener = new Camera.PictureCallback() {
        public void onPictureTaken(byte[] data, Camera camera) {
            if (data == null) {
                return;
            }

            String saveDir = Environment.getExternalStorageDirectory().getPath() + "/test";

            // retrieve the folder 
            File file = new File(saveDir);

            // creating a folder 
            if (!file.exists()) {
                if (!file.mkdir()) {
                    Log.e("Debug", "Make Dir Error");
                }
            }

            // saving the Path
            Calendar cal = Calendar.getInstance();
            SimpleDateFormat sf = new SimpleDateFormat("yyyyMMdd_HHmmss");
            String imgPath = saveDir + "/" + sf.format(cal.getTime()) + ".jpg";

            // ファイル保存
            FileOutputStream fos;
            try {


                fos = new FileOutputStream(imgPath, true);

//I want to merge the ImageView

                fos.write(data); //writing the data
                fos.close();

                registAndroidDB(imgPath);

            } catch (Exception e) {
                Log.e("Debug", e.getMessage());
            }

            fos = null;


            mCam.startPreview();

            mIsTake = false;
        }
    };