message: Fixed gray window for gpu stereo BP and CSBP
  compute() for BP and CSBP output 32-bit floating-point mat, and in cv::imshow() 32-bit floating-point is recognized as [0,1] and maped to [0,255], that causes gray window for BP and CSBP.
diff: @@ -212,7 +212,7 @@ void App::run()
  // Show results
  d_disp.download(disp);
  putText(disp, text(), Point(5, 25), FONT_HERSHEY_SIMPLEX, 1.0, Scalar::all(255));
  - imshow("disparity", disp);
  + imshow("disparity", (Mat_<uchar>)disp);
  handleKey((char)waitKey(3));
  }
  