Загрузка изображения с android на PHP сервер

в моем приложении я загружаю изображение с моего устройства на локальный веб-сервер... после выполнения кода .файл jpg создается на сервере, но не открывается. И размер файла на сервере отличается от исходного файла.

Android активность:--

public class MainActivity extends Activity {


private static int RESULT_LOAD_IMAGE = 1;
@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    Button btnSelectImage=(Button) findViewById(R.id.uploadButton);
    btnSelectImage.setOnClickListener(new OnClickListener() {

        @Override
        public void onClick(View v) {

        Intent i=new   Intent(Intent.ACTION_PICK,android.provider.MediaStore.Images.Media.EXTERNAL_CONTENT_URI);

        startActivityForResult(i, RESULT_LOAD_IMAGE);

        }
    });

}

@Override
protected void onActivityResult(int requestCode, int resultCode, Intent data) {
    // TODO Auto-generated method stub
    super.onActivityResult(requestCode, resultCode, data);

    if (requestCode == RESULT_LOAD_IMAGE && resultCode == RESULT_OK && data!=null) {

        Uri selectedImage=data.getData();
        String[] filePathColumn={MediaStore.Images.Media.DATA};

        Cursor cursor = getContentResolver().query(selectedImage,filePathColumn, null, null, null);
        cursor.moveToFirst();

        int columnIndex = cursor.getColumnIndex(filePathColumn[0]);
        String picturePath = cursor.getString(columnIndex);
        cursor.close();


        Bitmap bitmap=BitmapFactory.decodeFile(picturePath);

        ImageView im = (ImageView) findViewById(R.id.imgBox);
        im.setImageBitmap(bitmap);

        /*
         * Convert the image to a string
         * */
        ByteArrayOutputStream stream = new ByteArrayOutputStream();
        bitmap.compress(Bitmap.CompressFormat.PNG, 90, stream); //compress to which format you want.
        byte [] byte_arr = stream.toByteArray();
        String image_str = Base64.encodeToString(byte_arr,Base64.DEFAULT);

        /*
         * Create a name value pair for the image string to be passed to the server
         * */
        ArrayList<NameValuePair> nameValuePairs = new  ArrayList<NameValuePair>();            
        nameValuePairs.add(new BasicNameValuePair("image",image_str));


        JSONObject jsonString=new JSONObject();
        try {
            jsonString.put("img", image_str);
        } catch (JSONException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }

        new uploadImageToPhp().execute(jsonString);



    }


}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
    // Inflate the menu; this adds items to the action bar if it is present.
    getMenuInflater().inflate(R.menu.main, menu);


    return true;
}
public class uploadImageToPhp extends AsyncTask<JSONObject, Void, Void>
{
    String dataToSend=null;

    public static final String prefix="http://";                                                        //prefix of the urls
    public static final String server_ip="172.16.26.155";                                                   //the ip address where the php server is located    

    public static final String completeServerAddress=prefix+server_ip+"/test_upload/upload_image.php";                  //Exact location of the php files

    @Override
    protected Void doInBackground(JSONObject... params) {

        dataToSend="image="+params[0];
        communicator(completeServerAddress, dataToSend);




        return null;
    }

    public void communicator(String urlString,String dataToSend2)
    {
        String result=null;

        try
        {
            URL url=new URL(urlString);
            URLConnection conn=url.openConnection();

            HttpURLConnection httpConn=(HttpURLConnection) conn;
            httpConn.setRequestProperty("Accept", "application/json");
            httpConn.setRequestProperty("accept-charset", "UTF-8");
            httpConn.setRequestMethod("POST");         
            httpConn.connect();

            //Create an output stream to send data to the server
            OutputStreamWriter out=new OutputStreamWriter(httpConn.getOutputStream());
            out.write(dataToSend2);
            out.flush();

            int httpStatus = httpConn.getResponseCode();            
            System.out.println("Http status :"+httpStatus);

            if(httpStatus==HttpURLConnection.HTTP_OK)
            {
                Log.d("HTTP STatus", "http connection successful");

                BufferedReader in = new BufferedReader(new InputStreamReader(httpConn.getInputStream(),"UTF-8"));
                StringBuilder sb = new StringBuilder();
                String inputLine;
                while ((inputLine = in.readLine()) != null)
                {
                    System.out.println(inputLine);
                    sb.append(inputLine+"n");
                }
                in.close();
                result=sb.toString();                       

                try
                {

                    //jsonResult = new JSONObject(result);
                }
                catch(Exception e)
                {
                     Log.e("JSON Parser", "Error parsing data " + e.toString());
                }


            }
            else
            {
                System.out.println("Somthing went wrong");
            }
        } catch (MalformedURLException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        } catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }


    }


}

}

PHP код:-

 $recievedJson=$_REQUEST['image'];
$imageContent=json_decode($recievedJson,true);
 $base=$imageContent["img"];

 $binary=base64_decode($base);

 echo $binary;
header('Content-Type: bitmap; charset=utf-8');
$file = fopen('uploaded_image.jpg', 'wb');
fwrite($file, $binary);
fclose($file);