InputStream in = new java.net.URL(imageWebServiceURL).openStream();
String imageAsStringReadyForJson = getStringFromInputStream(in);

private String getStringFromInputStream(InputStream is) {
    BufferedReader br = null;
    StringBuilder sb = new StringBuilder();
    String line;
    try {
        br = new BufferedReader(new InputStreamReader(is));
        while ((line = br.readLine()) != null) {
            sb.append(line);
        }
    } catch (IOException e) {
        e.printStackTrace();
    } finally {
        if (br != null) {
            try {
                br.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
    }
    return sb.toString();
}

InputStream stream = new ByteArrayInputStream(stringFromJson.getBytes(Charset.forName("UTF-8")));
Bitmap photoBitmap = BitmapFactory.decodeStream(stream);
imageView.setImageBitmap(photoBitmap);