如何快速将大位图保存到SD卡？

Question

这是我目前将位图（2560x1440分辨率）保存到SD卡的代码：

private void saveImageToDiskTest()
{
    long startTime = System.currentTimeMillis();

    String fileName = "hid.png";
    String completePath = Environment.getExternalStorageDirectory() + "/Pictures/" + fileName;
    final Bitmap bitmap = BitmapFactory.decodeResource(getResources(), R.drawable.start_image_left);

    FileOutputStream out = null;
    try {
        out = new FileOutputStream(completePath);
        bitmap.compress(Bitmap.CompressFormat.PNG, 100, out);
    } catch (Exception e) {
        e.printStackTrace();
    } finally {
        try {
            if (out != null) {
                out.close();
            }
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    long stopTime = System.currentTimeMillis();
    long elapsedTime = stopTime - startTime;
    Toast.makeText(getApplicationContext(), String.valueOf(elapsedTime), Toast.LENGTH_LONG).show();
}

它有效，但速度很慢。保存图像需要10000毫秒。我该怎么做才能加快整个过程（不损失图像质量）？

我正在摩托罗拉Moto G gen2上测试它。