public static void saveBitmapAsPng(Bitmap bmp,File f) {
        try {
            FileOutputStream out = new FileOutputStream(f);
            bmp.compress(Bitmap.CompressFormat.PNG, 100, out);
            out.flush();
            out.close();
        } catch (FileNotFoundException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }