protected byte[] retrieveImageData() throws IOException {
        URL url = new URL(imageUrl);
        //HttpURLConnection connection = (HttpURLConnection) url.openConnection();
        HttpsURLConnection connection = (HttpsURLConnection) url.openConnection();

        // determine the image size and allocate a buffer
        int fileSize = connection.getContentLength();
        if (fileSize < 0) {
            return null;
        }
        byte[] imageData = new byte[fileSize];

        // download the file
        Log.d(LOG_TAG, "fetching image " + imageUrl + " (" + fileSize + ")");
        BufferedInputStream istream = new BufferedInputStream(connection.getInputStream());
        int bytesRead = 0;
        int offset = 0;
        while (bytesRead != -1 && offset < fileSize) {
            bytesRead = istream.read(imageData, offset, fileSize - offset);
            offset += bytesRead;
        }

        // clean up
        istream.close();
        connection.disconnect();

        return imageData;
    }