Bitmap changes size. Gets almost 20 times larger

Question

In my android app the user takes and saves a picture it is then converted to a bas64 string where it is about 55000 characters long. Then later in the program I retrieve the image and again convert it to a base64 string except now its over 2 million characters. Can any one explain why this happens?

code for re-retrieving the image.

Bitmap imgBitmap = MediaStore.Images.Media.getBitmap(getActivity().getContentResolver(), Uri.parse(imgFilePath));