Merge pull request #17570 from HannibalAPE:text_det_recog_demo

[GSoC] High Level API and Samples for Scene Text Detection and Recognition

* APIs and samples for scene text detection and recognition

* update APIs and tutorial for Text Detection and Recognition

* API updates:
(1) put decodeType into struct Voc
(2) optimize the post-processing of DB

* sample update:
(1) add transformation into scene_text_spotting.cpp
(2) modify text_detection.cpp with API update

* update tutorial

* simplify text recognition API
update tutorial

* update impl usage in recognize() and detect()

* dnn: refactoring public API of TextRecognitionModel/TextDetectionModel

* update provided models
update opencv.bib

* dnn: adjust text rectangle angle

* remove points ordering operation in model.cpp

* update gts of DB test in test_model.cpp

* dnn: ensure to keep text rectangle angle

- avoid 90/180 degree turns

* dnn(text): use quadrangle result in TextDetectionModel API

* dnn: update Text Detection API
(1) keep points' order consistent with (bl, tl, tr, br) in unclip
(2) update contourScore with boundingRect

modules/dnn/test/test_common.hpp

@@ -113,6 +113,14 @@ void normAssertDetections(
         double confThreshold = 0.0, double scores_diff = 1e-5,
         double boxes_iou_diff = 1e-4);
 
+// For text detection networks
+// Curved text polygon is not supported in the current version.
+// (concave polygon is invalid input to intersectConvexConvex)
+void normAssertTextDetections(
+        const std::vector<std::vector<Point>>& gtPolys,
+        const std::vector<std::vector<Point>>& testPolys,
+        const char *comment = "", double boxes_iou_diff = 1e-4);
+
 void readFileContent(const std::string& filename, CV_OUT std::vector<char>& content);
 
 #ifdef HAVE_INF_ENGINE