Unite deep learning object detection samples

doc/tutorials/dnn/dnn_yolo/dnn_yolo.markdown

@@ -18,40 +18,26 @@ VIDEO DEMO:
 Source Code
 -----------
 
-The latest version of sample source code can be downloaded [here](https://github.com/opencv/opencv/blob/master/samples/dnn/yolo_object_detection.cpp).
+Use a universal sample for object detection models written
+[in C++](https://github.com/opencv/opencv/blob/master/samples/dnn/object_detection.cpp) and
+[in Python](https://github.com/opencv/opencv/blob/master/samples/dnn/object_detection.py) languages
 
-@include dnn/yolo_object_detection.cpp
-
-How to compile in command line with pkg-config
-----------------------------------------------
-
-@code{.bash}
-
-# g++ `pkg-config --cflags opencv` `pkg-config --libs opencv` yolo_object_detection.cpp -o yolo_object_detection
-
-@endcode
+Usage examples
+--------------
 
 Execute in webcam:
 
 @code{.bash}
 
-$ yolo_object_detection -camera_device=0  -cfg=[PATH-TO-DARKNET]/cfg/yolo.cfg -model=[PATH-TO-DARKNET]/yolo.weights   -class_names=[PATH-TO-DARKNET]/data/coco.names
-
-@endcode
-
-Execute with image:
-
-@code{.bash}
-
-$ yolo_object_detection -source=[PATH-IMAGE]  -cfg=[PATH-TO-DARKNET]/cfg/yolo.cfg -model=[PATH-TO-DARKNET]/yolo.weights   -class_names=[PATH-TO-DARKNET]/data/coco.names
+$ example_dnn_object_detection --config=[PATH-TO-DARKNET]/cfg/yolo.cfg --model=[PATH-TO-DARKNET]/yolo.weights --classes=object_detection_classes_pascal_voc.txt --width=416 --height=416 --scale=0.00392
 
 @endcode
 
-Execute in video file:
+Execute with image or video file:
 
 @code{.bash}
 
-$ yolo_object_detection -source=[PATH-TO-VIDEO] -cfg=[PATH-TO-DARKNET]/cfg/yolo.cfg -model=[PATH-TO-DARKNET]/yolo.weights   -class_names=[PATH-TO-DARKNET]/data/coco.names
+$ example_dnn_object_detection --config=[PATH-TO-DARKNET]/cfg/yolo.cfg --model=[PATH-TO-DARKNET]/yolo.weights --classes=object_detection_classes_pascal_voc.txt --width=416 --height=416 --scale=0.00392 --input[PATH-TO-IMAGE-OR-VIDEO-FILE]
 
 @endcode
 

modules/dnn/include/opencv2/dnn/dnn.hpp

@@ -222,7 +222,7 @@ CV__DNN_EXPERIMENTAL_NS_BEGIN
         /** @brief Returns index of output blob in output array.
          *  @see inputNameToIndex()
          */
-        virtual int outputNameToIndex(String outputName);
+        CV_WRAP virtual int outputNameToIndex(String outputName);
 
         /**
          * @brief Ask layer if it support specific backend for doing computations.

samples/dnn/README.md

@@ -0,0 +1,20 @@
+# OpenCV deep learning module samples
+
+## Model Zoo
+
+### Object detection
+
+|    Model | Scale |   Size WxH|   Mean subtraction | Channels order |
+|---------------|-------|-----------|--------------------|-------|
+| [MobileNet-SSD, Caffe](https://github.com/chuanqi305/MobileNet-SSD/) | `0.00784 (2/255)` | `300x300` | `127.5 127.5 127.5` | BGR |
+| [OpenCV face detector](https://github.com/opencv/opencv/tree/master/samples/dnn/face_detector) | `1.0` | `300x300` | `104 177 123` | BGR |
+| [SSDs from TensorFlow](https://github.com/tensorflow/models/tree/master/research/object_detection/) | `0.00784 (2/255)` | `300x300` | `127.5 127.5 127.5` | RGB |
+| [YOLO](https://pjreddie.com/darknet/yolo/) | `0.00392 (1/255)` | `416x416` | `0 0 0` | RGB |
+| [VGG16-SSD](https://github.com/weiliu89/caffe/tree/ssd) | `1.0` | `300x300` | `104 117 123` | BGR |
+| [Faster-RCNN](https://github.com/rbgirshick/py-faster-rcnn) | `1.0` | `800x600` | `102.9801, 115.9465, 122.7717` | BGR |
+| [R-FCN](https://github.com/YuwenXiong/py-R-FCN) | `1.0` | `800x600` | `102.9801 115.9465 122.7717` | BGR |
+
+## References
+* [Models downloading script](https://github.com/opencv/opencv_extra/blob/master/testdata/dnn/download_models.py)
+* [Configuration files adopted for OpenCV](https://github.com/opencv/opencv_extra/tree/master/testdata/dnn)
+* [How to import models from TensorFlow Object Detection API](https://github.com/opencv/opencv/wiki/TensorFlow-Object-Detection-API)