message: Callib3d 4channel image detection
  3.2 version doesn't support 4 channel color image
  detections, unlike 3.1. Now, we don't call
  CV_Error() if 4 channel image is given.
  resolve
diff: @@ -442,7 +442,7 @@ int cvFindChessboardCorners( const void* arr, CvSize pattern_size,
  Mat img = cvarrToMat((CvMat*)arr).clone();
  - if( img.depth() != CV_8U || (img.channels() != 1 && img.channels() != 3) )
  + if( img.depth() != CV_8U || (img.channels() != 1 && img.channels() != 3 && img.channels() != 4) )
  CV_Error( CV_StsUnsupportedFormat, "Only 8-bit grayscale or color images are supported" );
  if( pattern_size.width <= 2 || pattern_size.height <= 2 )
  