String timeStamp = new SimpleDateFormat("yyyyMMdd_HHmmss").format(new Date());
        String imageFileName = "PNG_" + timeStamp + "_" + ".png";
        File imageFile = File(getExternalFilesDir(Environment.DIRECTORY_PICTURES), imageFileName);
            OutputStream stream = new FileOutputStream(imageFile);
            bbm.compress(Bitmap.CompressFormat.PNG,100,stream);
            stream.flush();
            stream.close();
        }catch (IOException e) // Catch the exception
            e.printStackTrace();
        }

        Uri savedImageURI = Uri.parse(file.getAbsolutePath());

        back.setImageURI(savedImageURI);