Android : how to Post parmeter in Json format to server for Uploading Image

public class UploadImage extends Activity {
    InputStream inputStream;

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        new myclass().execute();
    }

    class myclass extends AsyncTask<Void, Void, Void>

    {

        @Override
        protected Void doInBackground(Void... params) {
            // TODO Auto-generated method stub

            Bitmap bitmap = BitmapFactory.decodeResource(getResources(),
                    R.drawable.ic_launcher);
            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);
            ArrayList<NameValuePair> nameValuePairs = new ArrayList<NameValuePair>();

            try {
                String finalnamevalue;
                HttpClient httpclient = new DefaultHttpClient();
                HttpPost httppost = new HttpPost(
                        "http://api.lociiapp.com/api/registration/SaveProfilePicture");
                JSONObject contactsObj = new JSONObject();
                nameValuePairs.add(new BasicNameValuePair("member_id", "380"));
                nameValuePairs.add(new BasicNameValuePair("imageFile",
                        image_str));
                nameValuePairs.add(new BasicNameValuePair("picture_path",
                        "380.jpg"));

                httppost.setEntity(new UrlEncodedFormEntity(nameValuePairs));
                HttpResponse response = httpclient.execute(httppost);
                String the_string_response = convertResponseToString(response);

            } catch (Exception e) {

                System.out.println("Error in http connection " + e.toString());
            }

            return null;
        }

        public String convertResponseToString(HttpResponse response)
                throws IllegalStateException, IOException {

            String res = "";
            StringBuffer buffer = new StringBuffer();
            inputStream = response.getEntity().getContent();
            int contentLength = (int) response.getEntity().getContentLength(); // getting
                                                                                // content
                                                                                // length…..

            if (contentLength < 0) {
            } else {
                byte[] data = new byte[512];
                int len = 0;
                try {
                    while (-1 != (len = inputStream.read(data))) {
                        buffer.append(new String(data, 0, len)); // converting
                                                                    // to
                                                                    // string
                                                                    // and
                                                                    // appending
                                                                    // to
                                                                    // stringbuffer…..
                    }
                } catch (IOException e) {
                    e.printStackTrace();
                }
                try {
                    inputStream.close(); // closing the stream…..
                } catch (IOException e) {
                    e.printStackTrace();
                }
                res = buffer.toString(); // converting stringbuffer to string…..

                // System.out.println("Response => " +
                // EntityUtils.toString(response.getEntity()));
            }
            return res;
        }

    }
}

This is My code for Upload image to server i am able to send parameter to server in name value pair [member_id=380, imageFile=bytestream,picturepathe="380.jpg"] . while i have to Post parameter like this {[imageFile:"bystram",member_id:"380",picture_path:"380.jpg"]}

please help how i will make Name value pair in Json format