flip.java

    public static Bitmap flipHorizontallu(Bitmap bmp){
        Matrix matrix = new Matrix();
        matrix.postScale(-1.0f, 1.0f);
        return Bitmap.createBitmap(bmp, 0, 0, bmp.getWidth(), bmp.getHeight(), matrix, true);
    }

    public static Bitmap flipVertically(Bitmap bmp){
        Matrix matrix = new Matrix();
        matrix.postScale(1.0f, -1.0f);
        return Bitmap.createBitmap(bmp, 0, 0, bmp.getWidth(), bmp.getHeight(), matrix, true);
    }