Merge remote-tracking branch 'upstream/master' into bow_desc

Conflicts:
	modules/features2d/src/bagofwords.cpp

diff --cc modules/features2d/doc/object_categorization.rst
Simple merge

diff --cc modules/features2d/include/opencv2/features2d.hpp
Simple merge

diff --cc modules/features2d/src/bagofwords.cpp
index 11f8c4b,a257f6c..c0b4b26
--- 1/modules/features2d/src/bagofwords.cpp
--- 2/modules/features2d/src/bagofwords.cpp
+++ b/modules/features2d/src/bagofwords.cpp
@@@ -202,6 -176,21 +202,16 @@@ void BOWImgDescriptorExtractor::compute
  
      // Normalize image descriptor.
      imgDescriptor /= descriptors.rows;
 -
 -    // Add the descriptors of image keypoints
 -    if (_descriptors) {
 -        *_descriptors = descriptors.clone();
 -    }
  }
  
+ int BOWImgDescriptorExtractor::descriptorSize() const
+ {
+     return vocabulary.empty() ? 0 : vocabulary.rows;
+ }
+ 
+ int BOWImgDescriptorExtractor::descriptorType() const
+ {
+     return CV_32FC1;
+ }
+ 
  }